Foto personale

Ledi MENABUE

Department of Chemical and Geological Sciences

Nicolini, Valentina; Malavasi, Gianluca; Menabue, Ledi; Lusvardi, Gigliola; Benedetti, Francesco; Valeri, Sergio; Luches, Paola ( 2017 ) - Cerium-doped bioactive 45S5 glasses: spectroscopic, redox, bioactivity and biocatalytic properties - JOURNAL OF MATERIALS SCIENCE - n. volume 52 - pp. da 8845 a 8857 ISSN: 0022-2461 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The ability of Ce-containing bioactive glasses, based on 45S5 Bioglass®, to inhibit oxidative stress in terms of reduction in hydrogen peroxide and superoxide (O2−), by mimicking the catalase and superoxide dismutase activity is reported in this work. The characterization is performed on the powders of pristine glasses and after the soaking in H2O2solutions and simulated body fluid. The glass samples are analysed by XPS, XRD, UV–Vis and FT-IR. The best catalyst activities are obtained for the glass with the highest content of cerium (H_5.3 = 5.3 mol% of CeO2in the nominal glass composition), and the best Ce3+/Ce4+ratio in terms of catalase mimetic activity is found to be a function of H2O2concentration. Moreover, the detailed study of the surface during the mimic enzymatic activity tests shows the formation of a Ca-P-rich layer on the glass surface, where the presence of Ce ions favours the formation of CePO4. The phosphate in turn inhibits the formation of hydroxyapatite, decreasing the bioactivity of the glass with the highest of CeO2in the glass composition. This work shows the effect of Ce3+/Ce4+ratio towards the catalase mimetic activity and for the first time the superoxide dismutase mimetic activity of Ce-containing 45S5-derived glasses.

Malavasi, Gianluca; Nicolini, Valentina; Gambuzzi, Elisa; Menabue, Ledi; Lusvardi, Gigliola; Pedone, Alfonso; Benedetti, Francesco; Luches, Paola; D’Addato, Sergio; Valeri, Sergio ( 2016 ) - Abstracts from the X INSTM National Conference on Materials Science and Technology - Abstracts from the X INSTM National Conference on Materials Science and Technology “KE-MAT! Key Enabling Material” - JOURNAL OF APPLIED BIOMATERIALS & FUNCTIONAL MATERIALS - n. volume 14 - pp. da 0 a 0 ISSN: 2280-8000 [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

The ability of a Ce-containing bioactive glasses to inhibit oxidative stress in terms of reduction of H2O2, by mimicking the catalase enzyme activity is demonstrated for the first time. The antioxidant properties of bioactive glasses containing CeO2 have been evaluated by following the degradation of hydrogen peroxide with time after immersion in H2O2 aqueous solutions with different concentration. XPS, UV-Vis and magnetic measurements allowed us to determine the Ce3+/Ce4+ ratio (bulk and surface) and to correlate it with the ability of the samples to show catalase mimetic activity. We have found that the bioactive glass (23.2Na2O-25.7CaO-43.4SiO2-2.4P2O5-5.3CeO2) immersed in 0.1M H2O2 aqueous solution is able to degrade 90% of it in one week.

Nicolini, Valentina; Caselli, Monica; Ferrari, Erika; Menabue, Ledi; Lusvardi, Gigliola; Saladini, Monica; Malavasi, Gianluca ( 2016 ) - SiO2-CaO-P2O5 bioactive glasses: A promising curcuminoids delivery system - MATERIALS - n. volume 9 - pp. da 1 a 11 ISSN: 1996-1944 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this paper, we report the study of the loading and the release of curcuminoids by bioactive glasses (BG) and mesoporous bioactive glasses (MBG). Through a detailed spectroscopic study, it was possible to determine the amount and the type of molecules released in water and in simulated body fluid (SBF). In particular, curcumin and K2T21 show a good ability to be released in di-keto and keto-enolic form, depending from the pH. However, after 24 h, the amount of pristine curcumin release is very low with a consequent increment of degradation products derived by curcuminoids. The presence of -OH groups on curcuminoids is a fundamental pre-requisite in order to obtain a high loading and release in polar solution such as water and SBF. The substrate on which we loaded the drugs does not seem to affect significantly the loading and the release of the drugs. The environment, instead, affects the release: for all the drugs, the release in SBF, buffered at pH of 7.4, is slightly worse than the release in water (basic pH values).

Lusvardi, Gigliola; Malavasi, Gianluca; Menabue, Ledi; Smargiassi, Marco ( 2016 ) - Systematic investigation of the parameters that influence the luminescence properties of photoluminescent pigments - JOURNAL OF LUMINESCENCE - n. volume 175 - pp. da 141 a 148 ISSN: 0022-2313 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The formation and quantification of Sr4Al14O25:Eu2+/Dy3+, responsible of specific luminescent properties, was studied as a function of dopants, flux agents, temperature and time of synthesis; this phase was quantified by means of quantitative phase analysis (QPA), using X-Ray Powder Diffraction and Rietveld method. This kind of study gives the possibility to create a specific protocol to find selected parameters that influence the formation of Sr4Al14O25:Eu2+/Dy3+ and their photoluminescence properties. In particular, the present study put in light that a pigment with a slow afterglow decay (high performance by the point of view of its application) must be prepared using low ratios of dopants and varying the synthesis variables in order to maximize the quantity of Sr4Al14O25 as single crystalline phase and to minimize the amorphous phase. Among the synthesis variables, the use of a commercial flux agent based on NH4Cl is very important if compared with that used in the reference synthesis procedure

Nicolini, Valentina; Varini, Elena; Malavasi, Gianluca; Menabue, Ledi; Menziani, Maria Cristina; Lusvardi, Gigliola; Pedone, Alfonso; Benedetti, Francesco; Luches, Paola ( 2016 ) - The effect of composition on structural, thermal, redox and bioactive properties of Ce-containing glasses - MATERIALS & DESIGN - n. volume 97 - pp. da 73 a 85 ISSN: 0264-1275 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The effect of phosphate on the ability of Ce-containing bioactive glasses to inhibit oxidative stress was studied on compositions based on Hench (46.2%SiO224.3%Na2O26.9%CaO2.6P2O5, mol%) and Kokubo (50.0%SiO225.0%Na2O25.0%CaO) glasses. In particular, the reduction of catalase mimetic activity of Ce-containing glasses due to the presence: i) of P2O5 in the glass compositions, and ii) of phosphate groups in the solution employed for catalase mimetic activity tests was explained and rationalized by combining SEM, XPS, XRD, DTA, FT-IR and UV-vis experiments with Molecular Dynamics simulations.The results suggest that the Ce ions play a different structural role in the two series of glasses. In particular, in phosphate free glasses Ce is coordinated by non-bridging oxygens (NBOs) originated from the disruption of the silicate network, whereas in phosphate containing glasses the NBOs around Ce ions belong to orthophosphate groups. The latter groups stabilize the Ce3+ species subtracting them from the interconversion process between Ce3+ and Ce4+, which is of fundamental importance for the exhibition of the catalase mimetic activity.

Nicolini, Valentina; Gambuzzi, Elisa; Malavasi, Gianluca; Menabue, Ledi; Menziani, Maria Cristina; Lusvardi, Gigliola; Pedone, Alfonso; Benedetti, Francesco; Luches, Paola; D'Addato, Sergio; Valeri, Sergio ( 2015 ) - Evidence of catalase mimetic activity in ce(3+)/ce(4+) doped bioactive glasses - JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL - n. volume 119 - pp. da 4009 a 4019 ISSN: 1520-6106 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The ability of Ce-containing bioactive glasses to inhibit oxidative stress in terms of reduction of hydrogen peroxide, by mimicking the catalase enzyme activity is demonstrated here for the first time. The antioxidant properties of three bioactive glasses containing an increasing amount of CeO2 have been evaluated by following the degradation of hydrogen peroxide with time after immersion in H2O2 aqueous solutions with different concentration. XPS and UV-vis measurements allowed us to determine the Ce(3+)/Ce(4+) ratio in the bulk and on the glass surface, and to correlate it with the ability of the samples to show catalase mimetic activity. Interestingly, we have found that the bioactive glass with composition 23.2Na2O-25.7CaO-43.4SiO2-2.4P2O5-5.3CeO2 immersed in 0.1 M H2O2 aqueous solution is able to degrade 90% of it in 1 week. The reduction in bioactivity of the glasses with increasing CeO2 content is here rationalized in terms of a lower amount of phosphate groups available for the hydroxyapatite layer formation, after binding with cerium ions. In fact, classical molecular dynamics simulations revealed that the addition of CeO2 leads to the formation of cerium phosphate rich regions. The formation of an insoluble CePO4 crystalline phase is also observed by XRD analysis after thermal treatment of the glass samples.

Nicolini, Valentina; Malavasi, Gianluca; Ferrari, Erika; Benedetti, Francesco; Luches, Paola; Lusvardi, Gigliola; Castagnetti, Mattia; Valeri, Sergio; Saladini, Monica; Menabue, Ledi ( 2014 ) - Biovetri come potenziali drug delivery systems ed impianti con proprietà antiossidanti - Atti del XII Convegno Nazionale AIMAT [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Fra i biomateriali (“materiali progettati per essere usati a contatto con tessuti viventi, organismi o microorganismi”, definizione IUPAC), i biovetri ricevono un interesse sempre maggiore. Tali materiali trovano infatti largo impiego in chirurgia odontoiatrica ed ortopedica, nella produzione di impianti dentali, protesi o riempitivi ossei. Attualmente l’interesse è rivolto soprattutto ai biovetri di seconda e terza generazione: biovetri che oltre a formare un legame chimico coi tessuti che li circondano, sono capaci di indurre una specifica risposta a livello molecolare nei tessuti stessi, come l’osteoinduzione. I biovetri possono essere prodotti con processi ad alte temperature (metodo per fusione) o a basse temperature con i metodi Sol-Gel, ottenendo in questo caso biovetri porosi o con il metodo EISA ottenendo biovetri mesoporosi. Attualmente presso il nostro laboratorio due sono le linee di ricerca sui biomateriali: i) sintesi di biovetri Sol-Gel (BGSG) ed EISA (MBGSG) e verifica della possibilità di impiegarli come drug delivery systems (DDS) di molecole con proprietà antitumorali, quali i curcuminoidi; ii) sintesi per fusione di biovetri a partire dal vetro 45S5, drogati con CeO2 al fine di verificare la Catalase e SOD mimic-like activity di tali sistemi. Sui vetri porosi e mesoporosi, caricati con curcumina ed un suo derivato (K2T21) sono stati effettuati test di rilascio statico e dinamico in SBF. I rilasci sono stati quantificati ed in entrambi i casi le concentrazioni raggiunte dai farmaci nell’organismo sono nell’ordine del micromolare, ovvero sufficienti per manifestare l’attività antitumorale. Per ciò che concerne la valutazione della Catalase mimic-like activity, sono stati condotti test con H2O2 ed è stato verificato che i biovetri ottenuti per fusione manifestano questa proprietà. Sono inoltre in atto misure di rilascio di cerio in acqua e soluzione di SBF.

Valentina Aina;Gianluca Malavasi;Claudio Magistris;Giuseppina Cerrato;Gianmario Martra;Guido Viscardi;Ledi Menabue;Gigliola Lusvardi ( 2014 ) - Conjugation of amino-bioactive glasses with 5-aminofluorescein as probe molecule for the development of pH sensitive stimuli-responsive biomaterials - JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE - n. volume 25 - pp. da 2243 a 2253 ISSN: 0957-4530 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Bioceramics, such as silica-based glasses, are widely used in bone and teeth restoration. Nowadays, the association between nanotechnology and pharmacology is one of the most promising research fields in cancer therapy. The advanced processing methods and new chemical strategies allow the incorporation of drugs within them or on their functionalized surfaces. Bioceramics can act as local drug delivery systems to treat bone and teeth diseases. The present paper reports data related to the development of a pH-stimuli responsive bioactive glass. The glass conjugation with 5-aminofluorescein (5-AF), through a pH-sensitive organic spacer, allows to produce a pH-responsive bioactive biomaterial: when it is exposed to specific pH changes, it can favour the release of 5-AF directly at the target site. 5-AF has been chosen as a simple, low cost, non toxic model to simulate doxorubicin, an anticancer drug. As doxorubicin, 5-AF contains an amino group in its structure in order to form an amide bond with the carboxylic functionalities of the glass. Raman spectroscopy and thermal analysis confirm the glass conjugation of 5-AF by means of an amide bond; the amount of 5-AF loaded was very high (a parts per thousand 65 and 44 wt%). The release tests at two different pH (4.2 and 7.4) show that the amount of released 5-AF is higher at acid pH with respect to physiological one. This preliminary datum evidenced that a pH-sensitive drug delivery system has been developed. The low amount of 5-AF released (< 1 wt% of the total 5-AF) is due to the very low solubility of 5-AF in aqueous medium. This disadvantage, may be overcome in a dynamic environment (physiological conditions), where it is possible to obtain a drug release system ensuring an effective therapeutic dose for long times and, at the same time, avoiding the drug toxicity.

Sandra Sánchez-Salcedo;Shruti Shruti;Antonio J. Salinas;Gianluca Malavasi;Ledi Menabue;Maria Vallet-Regí ( 2014 ) - In vitro antibacterial capacity and cytocompatibility of SiO2–CaO–P2O5meso-macroporous glass scaffolds enriched with ZnO - JOURNAL OF MATERIALS CHEMISTRY. B - n. volume 2 - pp. da 4836 a 4847 ISSN: 2050-750X [Articolo in rivista (262) - Articolo su rivista]
Abstract

Zn2+ ions exhibit osteogenic, angiogenic and antimicrobial properties. For this reason, they are often added in small amounts to bioceramics being investigated for bone tissue engineering. In this paper, the cytocompatibility and antibacterial properties of 80% SiO2-15% CaO-5% P2O5 (mol%) mesoporous bioactive glass (MBG) scaffolds substituted with 4.0% and 7.0% of ZnO were studied and compared with the Zn-free scaffold. Cell proliferation, morphology, differentiation and cytotoxic effects of Zn2+ ions released from the samples were examined by culturing human osteoblast-tike cells (HOS) osteoblasts both in the presence of sample extracts and on the scaffold surface. The bacterial inhibition capacity of the scaffolds was explored by using Gram-positive Stapylococcus aureus bacteria, responsible for numerous infections in orthopedic surgery, to simulate a severe infection. Our results show that the Zn-MBG scaffolds possess a hierarchical meso-macropore structure suitable for osteobtast growth. Furthermore, the amount of Zn2+ released from the scaffold with 4.0% ZnO was found to be more favorable for HOS cell development than that released from the scaffold including 7.0% ZnO. Zn2+ released to the medium from both scaffolds exhibited antibacterial properties against S. aureus. Thus, the cytocompatibility and the antibacterial ability exhibited by the MBG scaffold containing 4.0% ZnO make it a suitable candidate for bone regeneration applications.

Valentina Aina;Claudio Magistris;Giuseppina Cerrato;Gianmario Martra;Guido Viscardi;Gigliola Lusvardi;Gianluca Malavasi;Ledi Menabue ( 2014 ) - New Formulation of Functionalized Bioactive Glasses to Be Used as Carriers for the Development of pH-Stimuli Responsive Biomaterials for Bone Diseases - LANGMUIR - n. volume 30 - pp. da 4703 a 4715 ISSN: 0743-7463 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The aim of the present contribution is to prepare a functionalized bioactive glass potentially useful as prosthetic material, but also able to release organic molecules in response to a change of the pH environment. By this approach it is possible to develop devices which can be used for a triggered drug release in response to specific stimuli; this is an attractive research field, in order to avoid either systemic and/or local toxic effects of drugs. In particular, in the present paper we report data related to the development of a new formulation of bioactive glasses, their functionalization with organic molecules to obtain a pH-sensitive bond, their physicochemical characterization and in vitro bioactivity in simulated biological fluids (SBF), and organic molecule delivery tests at different pH. The glass functionalization, by means of a covalent reaction, allows us to produce a model of pH-responsive bioactive biomaterial: when it is exposed to specific pH changes, it can favor the release of the organic molecules directly at the target site. Cysteamine and 5-aminofluorescein are used as model molecules to simulate a drug. The materials, before and after the different functionalization steps and in vitro release tests at different pH, have been characterized by means of different experimental techniques such as X-ray powder diffraction (XRPD), Raman, FTIR and fluorescence spectroscopies, N-2 adsorption, thermogravimetric (TGA) and elemental analysis.

Lusvardi, Gigliola; Malavasi, Gianluca; Menabue, Ledi; Menziani, Maria Cristina; Pedone, Alfonso ( 2013 ) - Bioglasses: glasses for medical applications - 12th international conference on the structure of non crystalline materials - tipografia unitn trento ITA) - n. volume 1 - pp. da 72 a 72 ISBN: 978-88-8443-490-6 ISSN: - [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

bioglasses for medical applications

Shruti Shruti; Antonio J. Salinas; Erika Ferrari; Gianluca Malavasi; Gigliola Lusvardi; Antonio L. Doadrio; Ledi Menabue; M. Vallet-Regi ( 2013 ) - Curcumin release from cerium, gallium and zinc containing mesoporous bioactive glasses - MICROPOROUS AND MESOPOROUS MATERIALS - n. volume 180 - pp. da 92 a 101 ISSN: 1387-1811 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Curcumin is the main component of turmeric which is being used since centuries due to medicinal ben- efits with no side effects. In this paper, 80%SiO2–15%CaO–5%P2O5 mesoporous bioactive glasses (MBGs) containing two different concentrations of Ce2O3, Ga2O3 (1.0% and 2.0%) and ZnO (2.0% and 4.0%) (in mol%) were synthesized by evaporation induced self-assembly (EISA) method to investigate their potential as drug delivery system (DDS) for curcumin. Impregnation method was applied for incorporat- ing curcumin into MBGs and in vitro release was performed in simulated body fluid (SBF) at 37 °C up to 72 h. The substituted MBGs exhibited mesostructure and textural properties good enough for drug deliv- ery. Highest gallium and cerium substituted MBGs incorporated drug more than unsubstituted MBG (B_MBG) due to high affinity of curcumin towards hard Lewis acids. However, during in vitro drug release, B_MBG and lowest cerium, gallium and zinc substituted MBGs showed curcumin release that is capable to exert pharmacological activities. On the other hand, strong interaction between curcumin and substituent caused reduction in drug release from the other set of MBGs with negligible release from 2.0%Ga2O3. Furthermore, MBGs loaded with curcumin showed quick in vitro response except 4.0%ZnO. Hence, lowest Ce, Ga and Zn substituted MBGs can be considered as drug release system for curcumin because they showed higher drug release with quick in vitro bioactivity and the added values of the substituents.

Lusvardi G.; Malavasi G.; Menabue L.; Shruti S. ( 2013 ) - Gallium-containing phosphosilicate glasses: functionalization and vitro bioactivity - MATERIALS SCIENCE AND ENGINEERING. C, BIOMIMETIC MATERIALS, SENSORS AND SYSTEMS - n. volume 33 - pp. da 3190 a 3196 ISSN: 0928-4931 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A gallium containing glass 45.7SiO2•24.1Na2O•26.6CaO•2.6P2O51.0Ga2O3, referred to as Ga1.0, and a parent Ga-free glass 46.2 SiO2•24.3Na2O•26.9CaO•2.6P2O5, corresponding to Bioglass® 45S5, (H glass) were functionalized with Tetraethoxysilane (TEOS) and (3-Aminopropyl)triethoxysilane (APTS) in order to improve the ability of the glasses to bond biomolecuels. Functionalization with TEOS and APTS promoted increment in OH groups and formation of NH2 groups on the glass surface, respectively. The presence of OH or NH2 groups was investigated by means of IR spectroscopy and elemental analysis. Functionalized glasses were investigated by an in-vitro study in simulated body fluid (SBF) for defining the effect of functionalization on their bioactivity as compared to plain glasses. The results showed that the functionalization was obtained and bioactivity was maintained: the surfaces of both functionalized glasses were covered by a layer of apatite by 30 days of immersion in SBF. In addition, CaCO3 was also identified on the surface of APTS functionalized glasses. No gallium release was detected during the immersion in SBF.

V. Aina;G. Cerrato;G. Martra;L. Bergandi;C. Costamagna;D. Ghigo;G. Malavasi;G. Lusvardi;L. Menabue ( 2013 ) - Gold-containing bioactive glasses: a solid-state synthesis to produce alternative biomaterials for bone implantations - JOURNAL OF THE ROYAL SOCIETY INTERFACE - n. volume 10 - pp. da 20121040 a 20121040 ISSN: 1742-5689 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A new melted bioactive system containing gold nanoparticles (AuNPs) was prepared exploiting a post-synthesis thermal treatment that allows one to modify crystal phases and nature, shape and distribution of the gold species in the glass-ceramic matrix as evidenced by UV-visible spectroscopy, transmission electron microscopy and powder X-ray diffraction analysis. In human MG-63 osteoblasts the presence of Aun+ species caused an increase of lactate dehydrogenase leakage and malonyldialdehyde production, whereas Hench's Bioglass HAu-600-17 containing only AuNPs did not cause any effect. In addition, HAu-600-17 caused in vitro hydroxyapatite formation and an increase of specific surface area with a controlled release of gold species; this material is then suitable to be used as a model system for the controlled delivery of nanoparticles.

S. Shruti; A.J. Salinas; G. Lusvardi; G. Malavasi; L. Menabue; M. Vallet-Regi. ( 2013 ) - Mesoporous bioactive scaffolds prepared with cerium-, gallium- and zinc-containing glasses - ACTA BIOMATERIALIA - n. volume 9 - pp. da 4836 a 4844 ISSN: 1742-7061 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Mesoporous bioactive glass scaffolds (MBG-Scs), based on 80% SiO 2-15% CaO-5% P 2O 5 (in mol.%) mesoporous sol-gel glasses substituted with Ce 2O 3, Ga 2O 3 (both 0.2% or 1.0%) and ZnO (0.4% or 2.0%), were synthesized by combination of evaporation-induced self-assembly and rapid prototyping techniques. Cerium, gallium and zinc trace elements were selected because of their inherent beneficial biological properties. Fabricated scaffolds were characterized and compared with unsubstituted scaffold (B-Sc). All of them contained well interconnected ultralarge pores (pores >400 μm) ideal for vascular ingrowth and proliferation of cells. Macropores of size 100-400 μm were present inside the scaffolds. In addition, low-angle X-ray diffraction showed that B-Sc and scaffolds with substituent contents up to 0.4% exhibited ordered mesoporosity useful for hosting molecules with biological activity. The textural properties of B-Sc were a surface area of 398 m 2 g -1, a pore diameter of 4.3 nm and a pore volume of 0.43 cm 3 g -1. A slight decrease in surface area and pore volume was observed upon substitution with no distinct effect on pore diameter. In addition, all the MBG-Scs except 2.0% ZnO-Sc showed quite quick in vitro bioactive response. Hence, the present study is a positive addition to ongoing research into preparing bone tissue engineering scaffolds from bioceramics containing elements of therapeutic significance.

G. Malavasi; L. Menabue; M. C. Menziani;A. Pedone; A. J. Salinas; M. Vallet-Regı. ( 2013 ) - New insights into the bioactivity of SiO2–CaO and SiO2–CaO–P2O5 sol–gel glasses by molecular dynamics simulations - JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY - n. volume 67 - pp. da 208 a 219 ISSN: 0928-0707 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The structures of binary xCaO . (100 - x)SiO2glasses with x = 10, 20 and 30 mol-% and ternary(20 - x)CaO . xP2O5 . 80SiO2 glasses with x = 3, 10, 15,17 and 20 mol-% have been studied by means of classicalmolecular dynamics simulations using both the melt-quenchedand the sol–gel protocols. The structural picturederived correlates the bioactive behaviour to the combinedeffects of the connectivity of the extended silicate networkand to the tendency to form (or not to form) non-homogeneousdomains. In this context, a mathematical relationshipthat relates the Ca/P ratio in the Ca phosphatemicro-segregation zones to the P2O5 content in ternaryglasses has been developed and this has been used to finetuningthe optimum amount of P in a glass for its highest invitro bioactivity. The composition with optimal Ca/P ratio,80SiO2 . 14.8CaO . 5.2P2O5 has been synthesized and the results of bioactivity tests have confirmed the prediction.

V. Aina; G. Cerrato; G. Martra; G. Malavasi; G. Lusvardi; L. Menabue ( 2013 ) - Toward the controlled release of metal nanoparticles from biomaterials: physico-chemical, morphological and bioactivity features of Cu-containing sol gel glasses - APPLIED SURFACE SCIENCE - n. volume 283 - pp. da 240 a 248 ISSN: 0169-4332 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Two Cu-containing bioactive glasses were prepared and characterized in order to obtain a detailed description of chemical, morphological and bioactivity proprieties of potential Cu releasing systems. The characterization has demonstrated that by varying the synthesis procedure is possible to obtain two systems with Cu species in two different oxidation states and aggregation: (i) SGCu(ox) - oxidated Cu - (Cu oxidation state +2) homogeneously dispersed in the glass network matrix and (ii) SGCu(red) - metallic Cu - (Cu oxidation state 0) containing nano-particles (5-130 nm range) mainly present on the glass surface. The introduction of Cu maintains the bioactivity of the Cu-containing glasses almost unchanged, inducing a partial delay in the hydroxyapatite/ hydroxy-carbonate apatite (HA/HCA) formation on the glass surface with respect to the reference glass (free Cu glass). During the bioactivity test, Cu is released from both Cu-containing glasses, in particular in the case of the SGCu(red) the presence of Cu nanoparticles (CuNPs) of diameter in the range 5-10 nm has been detected in solution. © 2013 Elsevier B.V. All rights reserved.

Marina Cocchi; Caterina Durante; Gigliola Lusvardi; Gianluca Malavasi;Ledi Menabue ( 2012 ) - Evaluation of the behaviour of fluorine-containing bioactiveglasses: reactivity in a simulated body fluid solution assistedby multivariate data analysis - JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE - n. volume 23 - pp. da 639 a 648 ISSN: 0957-4530 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Potentially bioactive fluorine-containing glassesof formula 46.2SiO224.3Na2O(26.9-x)CaO2.6P2O5xCaF2 [x = (0), 5, 10, 15] have been studied: the study wascarried out as a function of fluorine percentage, dimensionsand time of soaking in SBF. The results are compared tothose obtained in the same conditions for Bioglass 45S5.Due to the high number and different kind of variables/conditions explored by this set of data, the results arerationalized for the first time by means of multivariate dataanalysis (MDA); in this way it is possible to classify thebehaviour of bioglasses toward bioactivity. The presence offluorine does not inhibit the formation of HA; in particular,for a fast bioactivity (in term of HA crystallization) it willbe better to have large particle size or slabs, while for a fastdissolution fine particle sizes should be preferred.

Mirco Franchini; Gigliola Lusvardi; Gianluca Malavasi; Ledi Menabue ( 2012 ) - Gallium-containing phospho‐silicate glasses: Synthesis and in vitro bioactivity - MATERIALS SCIENCE AND ENGINEERING. C, BIOMIMETIC MATERIALS, SENSORS AND SYSTEMS - n. volume 32 - pp. da 1401 a 1406 ISSN: 0928-4931 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A series of Ga-containing phospho-silicate glasses based on Bioglass 45S5, having molar formula 46.2SiO2·24.3Na2O·26.9CaO·2.6P2O5·xGa2O3 (x=1.0, 1.6, 3.5), were prepared by fusion method. The reference Bioglass45S5 without gallium was also prepared. The synthesized glasses were immersed in simulated body fluid (SBF) for 30 days in order to observe ion release and hydroxyapatite (HA) formation. All Ga-containing glasses maintain the ability of HA formation as indicated by main X-ray diffractometric peaks and/or electronic scanning microscopy results. HA layer was formed after 1 day of SBF soaking in 45S5 glass containing up to 1.6% Ga2O3 content. Moreover, gallium released by the glasses was found to be partially precipitated on theglass surface as gallium phosphate. Further increase in gallium content reduced the ion release in SBF. The maximum of Ga3+ concentration measured in solution is ~6 ppm determined for 3.5% Ga2O3 content. This amount is about half of the toxic level (14 ppm) of gallium and the glasses release gallium till 30 days of immersionin SBF. Considering the above results, the studied materials can be proposed as bioactive glasses with additional antimicrobial effect of gallium having no toxic outcome.

V.Aina; G.Lusvardi; B.Annaz; I.R.Gibson; F.E.Imrie; G.Malavasi; L.Menabue; G.Cerrato; G.Martra ( 2012 ) - Magnesium- and strontium-co-substituted hydroxyapatite: the effects of doped ions on the structure and chemico-physical properties - JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE - n. volume 23 - pp. da 2867 a 2879 ISSN: 0957-4530 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Mg(II) and Sr(II) ions were substituted for Ca(II) into the hydroxyapatite structure by means of wet synthesis. The materials were characterizad by X-ray diffractometry, IR and Raman spectroscopy and SEM analysis.The results showed the formation of tricalcio phosphate along with hydroxyapatite with change in cell parameters and crystallinity degree as a function of % substitution.

Malavasi G.; Lusvardi G.; Menabue L.; Ferrari E.; Saladini M.; Aina V.; Martra G.; Bergandi L.; Ghigo D.; Valetti F. ( 2012 ) - Novel smart bio-nanomaterials: Bioactive glasses containing metal nano-particles conjugated with molecules of biological interest ( Conference Paper ) - Techical proceedings of the 2012 NSTI Nanotechnology Conference and EXPO, NSTI-Nanotech 2012 - CRC Press Taylor&Francis Group Boca Raton, FL USA) - n. volume Vol. 3 - pp. da 114 a 117 ISBN: 9781466562769 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

New smart materials based on phospho-silicate bioactive sol-gel glasses have been developed. To meet the ever-increasing demand for performing bio-materials, the surface features of the glasses have been tailored to achieve optimal behaviour in different applications (drug delivery, enzymes activity, chemo-signalling probe, stimuli-sensitive agents). In particular, the introduction on the glass surface of metal nanoparticles (NPs; Au and Cu are the metals) is very useful because the NPs can directly act, for example, as bactericides and imaging agents and can be used to immobilize, via a covalent linkage, an enzyme/protein and/or a drug on the glass surface. This can be achieved through the formation of self-assembled monolayers (SAMs), in order to obtain a stable bio-conjugate system. The systems prototyped in this way could be useful as materials bio-implantable into the human body. In the present contribution we report the development of smart bio-materials. In particular, it is demonstrated that bioactive glasses containing Au nanoparticles (AuNPs) can be selectively functionalized with small molecules carrying either amino or thiol groups by simply varying the temperature and pH of the functionalization batch. These results should allow the production, in a selective way, of different bonds exhibiting different strengths and, consequently, different release times in solution, with a wide range of possible applications. (For instance, weak Au-N bonds in the case of drug delivery, strong Au-S bonds for protein immobilization). Unlike other works, in which a preliminary silanization process has often been used, the introduction of AuNPs in the glass composition allows to exploit the easy SAMs formation process on the AuNPs dispersed in the bioactive glass matrix and, consequently, to immobilize an enzyme (soybean peroxidase, SBP). A thorough characterization of the materials, at different steps of the functionalization process, is also reported, together with in vitro activity tests of immobilized SBP, compared with merely adsorbed SBP, and cytotoxicity tests using human osteoblast (MG-63) cells. Overall, a new bio-conjugate material, able to maintain its activity over time and to decrease the oxidative stress when in contact with MG-63 cells, has been obtained. In the present work we have also prepared and characterized bioactive glasses containing CuNPs in order to prepare antibacterial biomaterials useful in the field of implantation surgery.

Shruti S.; Salinas A.; Menabue L.; Lusvardi G.; Malavasi G.; Ferrara C.; Mustarelli P.; Vallet Regi M. ( 2012 ) - Structural and in-vitro study of cerium, gallium and zinc containing sol-gel bioactive glasses - JOURNAL OF MATERIALS CHEMISTRY - n. volume 22 - pp. da 13698 a 13706 ISSN: 0959-9428 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Sol–gel derived glasses comprised of bioactive materials exhibit a high in vitro response, i.e., the capability to form a hydroxycarbonate apatite (HCA) layer that is claimed to be responsible for the bonding between the glass and the host bone. In this paper, the sol–gel bioactive glass 80% SiO2–15% CaO–5% P2O5(B_BG) was modified by adding the biologically relevant elements cerium, gallium and zinc. Structural characterization of the glasses was performed by 29Si MAS NMR and their in vitro response was investigated by soaking them in simulated body fluid (SBF) for up to 15 days at 37 °C. The HCA formation was monitored by XRD, FTIR, SEM-EDS and ICP measurements. Ce3+, Ga3+, and Zn2+can be classified as “intermediate ions”. However, 29Si NMR revealed that Ce3+ions have a more marked role of “modifier ions” than Ga3+ions, while the behavior of Zn2+lies between those of Ce3+and Ga3+. On the other hand, in spite of the decrease in the in vitro response of B_BG by substitution, the glasses show HCA formation after 15 days of soaking. In addition, an increase in substitution of zinc accelerated the formation of HCA along with the formation of the mixed phase CaZn2(PO4)2·2H2O (scholzite) acting as nucleating agent for HCA. Moreover, the therapeutic effect of optimum Zn released as an ionic dissolution product from Zn-glasses could be beneficial to stimulate osteogenesis.

Alberto Bonici; Gigliola Lusvardi; Gianluca Malavasi; Ledi Menabue; Andrea Piva ( 2012 ) - Synthesis and characterization of bioactive glasses functionalized with Cu nanoparticles and organic molecules - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 32 - pp. da 2777 a 2783 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Bioactive sol gel glasses, based on the ternary system 15CaO·5P2O5·80SiO2, doped with Cu were synthesized and characterized in order to definethe oxidation state of Cu as a function of thermal treatments. In particular, we were able to optimize the condition to obtain: (i) the reduction ofCu2+ to Cu0 followed by nano-aggregation of metal nano-particles (MeNPs) into glass matrix; (ii) a mixed Cu2+/Cu+/Cu0 NPs-containing glasses;(iii) a Cu2+-containing glasses.Successively, the surface of sol–gel glasses was functionalized by means of organic molecules (amino and mercapto alcohols) to give rise to asystem that can interact with the functional groups of the drugs. The functionalization was carried out as a function of the sol–gel glass composition,organic molecules concentration and temperature of the process; the results indicate a preference for the amino groups. The bioactivity (formationof an apatitic layer after simulated body fluid SBF test) was verified for the functionalized sol–gel Cu2+-containing glasses and they are stillbioactive.

Valentina Aina; Claudio Morterra; Gigliola Lusvardi; Gianluca Malavasi; Ledi Menabue; Shruti Shruti; Claudia Letizia Bianchi;Vera Bolis ( 2011 ) - Ga-Modified (Si-Ca-P) Sol-Gel Glasses: Possible Relationships Between Surface Chemical Properties and Bioactivity - JOURNAL OF PHYSICAL CHEMISTRY. C. - n. volume 115 - pp. da 22461 a 22474 ISSN: 1932-7455 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In vitro bioactivity features of a Ga-modified sol gel Si-Ca-P glass(SGGa) were investigated, in comparison with a plain ternary Si-Ca-P system(SG). Reaction/dissolution of the glass at increasing soaking times in simulatedbody fluids (SBF) and the consequent growth of an apatite-like layer, monitoringbioactivity, were studied by employing a variety of chemical and physical techniques.The growth of a crystalline apatitic layer at the Ga-modified-glass/SBFinterface is severely delayed with respect to the Ga-free glass, and the reasons for ithave been looked for in the dramatic changes induced, at the glass/SBF interface, bythe presence of the Ga2O3 component. In situ Fourier transform infraredspectroscopy allowed to describe the nature/structure of surface terminations forthe two glasses and to reveal/quantify the acidic strength of different Ga speciesexposed at the SGGa glass surface. 2,6-Dimethylpyridine and carbon monoxidewere employed as molecular probes to reveal Brønsted and Lewis acidity. At thesurface of the Ga-modified glass, both Brønsted and strong Lewis acidic sites are present. The enhanced surface acitiy of SGGa glass,with respect to the plain glass SG, has been proposed to be responsible for the slower glass dissolution in SBF and for the delayeddeposition/crystallization of an apatite-like layer at the glass/SBF interface.

V. Aina; D. Ghigo;T. Marchis; G. Cerrato; E. Laurenti; C. Morterra;G. Malavasi; G. Lusvardi; L. Menabue; L. Bergandi ( 2011 ) - Novel bio-conjugate materials: soybean peroxidase immobilized on bioactiveglasses containing Au nanoparticles - JOURNAL OF MATERIALS CHEMISTRY - n. volume 21 - pp. da 10970 a 10981 ISSN: 0959-9428 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In the field of implantation, the delivery and/or immobilization of biomolecules developing a specificaction on bone mineralization has attracted great attention in the last few years. In fact, a widespectrum of enzymes and proteins have been grafted with different methods onto/within implantedmaterials. Bioactive glasses and glass-ceramics, due to their tailorable properties in terms of chemicalcomposition, reactivity, and easiness of manufacturing, represent good scaffolds for enzymeimmobilization. These biomaterials are well known for their peculiar surface reactivity promoting,when contacted with real or simulated body fluids, the formation of an hydroxy-carbonate apatitelayer. The aim of the present contribution has been to immobilize, via a covalent linkage, an enzyme onthe glass surface through the formation of self-assembled monolayers (SAMs), in order to obtaina stable bio-conjugate useful as a material bio-implantable into the human body. The innovation of thisstudy resides in the use of a new method of protein immobilization on the glass surface. Unlike otherworks, in which a preliminary silanization process has often been used, the introduction of goldnanoparticles (AuNPs) in the glass composition allowed us to exploit the easy SAMs formation processon the AuNPs dispersed in the bioactive glass matrix and, consequently, to immobilize an enzyme(soybean peroxidase, SBP, in the present case) on the SAMs. A thorough characterization of thematerials, at different steps of the functionalization process, has been also reported, together with invitro activity tests of immobilized SBP, compared with merely adsorbed SBP, and cytotoxicity testsusing human osteoblast (MG-63) cells. Overall, a new bio-conjugate material, able to maintain itsactivity over time and to decrease the oxidative stress when in contact with MG-63 cells, has beenobtained.

G. Malavasi; G. Lusvardi; L. Menabue; E. Ferrari; M. Saladini; V. Aina; C. Monterra; E. Laurenti; L. Bergandi; D. Ghigo ( 2011 ) - Novel smart bio-materials: bioactive glasses containing metal nano-particles conjugated with molecules of biological interests - Atti del XXXIX Congresso Nazionale di Chimica Inorganica - XXIV Congresso Nazionale della Società Chimica Italiana - Società chimica Italiana Lecce ITA) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Novel smart bio-materials: bioactive glasses containing metal nano-particles conjugated with molecules of biological interests

V.Aina; L.Bertinetti; G.Cerrato; M.Cerruti; G.Lusvardi; G.Malavasi; C.Morterra; L.Tacconi; L.Menabue ( 2011 ) - On the dissolution/reaction of small-grain Bioglass 45S5 and F-modified bioactive glasses in artificial saliva (AS) - APPLIED SURFACE SCIENCE - n. volume 257 - pp. da 4185 a 4195 ISSN: 0169-4332 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction of small-grain Bioglass® 45S5 in artificial saliva (AS), to produce a layer of hydroxy-apatite(HA) and/or hydroxy-carbonate apatite (HCA), has been studied and compared to the results obtained in asimple buffered solution (TRIS). Some potentially bioactive glasses based on the composition of Bioglass®and containing CaF2 (HCaCaF2 5% and HNaCaF2 5%) have also been studied, in order to analyze theeffects/changes produced when a F-containing glass surface is contacted with AS. The insertion of fluorinehas been proposed to improve bioactive glass bone-bonding ability, and to parallel fluorine-containingglass-ceramics currently used in dentistry. ICP-OES analysis of the solution, and FTIR spectroscopy of thesolid samples provided compositional information on the stages of reaction. These data were integratedwith XRD and the textural and morphological data, obtained by specific surface areas determination andTEM-EDS measurements. In the case of Bioglass® 45S5, a comparison at corresponding reaction timesindicates that the precipitation of an amorphous Ca-phosphate phase is faster in AS, but the crystallizationof HA/HCA is delayed in AS with respect to the TRIS solution. For fluoride-containing glasses, the sampleHCaCaF2 5%, in which CaF2 replaces part of CaO, possesses the fastest rate for HA/HCA crystallization (1week) in AS. Some lines of interpretation for these results are proposed.

A.J. Salinas; S. Shruti; G. Malavasi; L. Menabue; M. Vallet-Regí ( 2011 ) - Substitutions of cerium, gallium and zinc in ordered mesoporous bioactive glasses - ACTA BIOMATERIALIA - n. volume 7 - pp. da 3452 a 3458 ISSN: 1742-7061 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Ordered mesoporous glasses based on the 80% SiO2–15% CaO–5% P2O5 system including up to 3.5% Ce2O3,3.5% Ga2O3 or 7.0% ZnO (in mol.%) were synthesized by the evaporation-induced self-assembly processusing Pluronic 123 as a surfactant. An ordered hexagonal mesophase was observed in both the unsubstitutedglass (denoted in this paper as B: blank) and glasses containing <0.4% of substituent by X-ray diffraction,transmission electron microscopy and electron diffraction. The increase in the amount ofsubstituent led to a decrease in the mesopore order. B glass exhibited good textural properties:SBET = 515 m2 g1, DP = 4.7 nm and VP = 0.58 cm3 g1. With the inclusion of cerium, gallium and zinc oxidesthe textural properties decreased, but remained in amounts useful for clinical applications. Zinc-containingsamples showed the highest decrement in the textural properties. Substituted glasses exhibited aquick in vitro bioactive response except when the ZnO content was over 0.4%. Taking into account theordered mesoporosity, the quick in vitro bioactive response and the added values of the substituents, thisnew family of glasses are promising candidates for applications in bone tissue engineering.

E. Ferrari; G. Lusvardi; V. Aina; G. Malavasi; F. Fantini; C. Morterra; F. Pignedoli; M. Saladini; L. Menabue ( 2011 ) - The role of coordination chemistry in the development of innovative Gallium-based bioceramics: the case of Curcumin - JOURNAL OF MATERIALS CHEMISTRY - n. volume 21 - pp. da 5027 a 5037 ISSN: 0959-9428 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Curcumin, an active ingredient in the traditional Ayurvedic herbal remedy [Curcuma longa L.], isnowadays also employed in western medicine for its pleiotropic activities, ranging from anticancer to itsfree radical scavenger ability. These features are related to curcumin’s function as a metal chelator,especially being selective for hard Lewis acids, such as Ga3+ which has interesting pharmacologicalactivities. We report the synthesis and characterization of a bioactive gel and mesoporous Ga-containing phospho-silicate glasses loaded with curcumin, in which, for the first time, coordinationchemistry was taken advantage of in designing novel drug delivery systems. In particular, it was foundthat: (i) there is a direct correlation between the external surface area and the amount of loadedcurcumin; (ii) the presence of Ga3+ species on the surface increases the quantity of drug moleculesuploaded and slows down their release in the biological medium (SBF), hinting at a coordination-likeinteraction between curcumin and the surface metal ions; (iii) curcumin molecules released in the SBFsolution stabilize Ga3+ ions, avoiding their precipitation.

Gigliola Lusvardi; Gianluca Malavasi; Valentina Aina; Luca Bertinetti; Giuseppina Cerrato;Giuliana Magnacca; Claudio Morterra; Ledi Menabue ( 2010 ) - Bioactive Glasses Containing Au Nanoparticles. Effect of Calcination Temperature on Structure, Morphology, and Surface PropertiesDOI:10.1021/la100472p - LANGMUIR - n. volume 26 - pp. da 10303 a 10314 ISSN: 0743-7463 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Bioactive glasses containing gold nanoparticles (AuNPs) have been synthesized via the sol-gel route usingHAuCl4 x 3H2O as gold precursor. The formation process of AuNPs was studied as a function of the thermal treatment,which induces nucleation of Au particles and influences their nature, optical properties, shape, size, and distribution.The physicochemical characterization indicates that the sample treated at 600 °C presents the best characteristics to beused as a bioactive material, namely high surface area, high amount of AuNPs located at the glass surface, presence ofmicropores, and abundant surface OH groups. In the case of samples either aged at 60 °C or calcined at 150 °C, AuNPsjust begin their formation, and at this stage the gel is not completely polymerized and dried yet. A thermal treatment athigher temperatures (900 °C) causes the aggregation of AuNPs, forming “AuMPs” (i.e., Au microparticles) in adensified glass-ceramic material with low surface area, absence of pores, and low number of surface OH groups. Thesefeatures induce in the glass-ceramic materials treated at high-temperatures a lower bioactivity (evidenced by SBFreaction), as compared with that exhibited by the glass samples treated at 600 °C.

V. Aina; T. Marchis; E. Laurenti; E. Diana; G. Lusvardi; G. Malavasi; L. Menabue; G. Cerrato; C. Morterra ( 2010 ) - Functionalization of sol gel bioactive glasses carrying Au nanoparticles: selective Au affinity for amino and thiol ligand groups - LANGMUIR - n. volume Vol. 26(24) - pp. da 18600 a 18605 ISSN: 0743-7463 [Articolo in rivista (262) - Articolo su rivista]
Abstract

It is demonstrated here that bioactive glasses containing Au nanoparticles (AuNPs) can be selectively functionalizedwith small molecules carrying either amino or thiol groups by simply varying the temperature and pH of thefunctionalization batch. The results evidence the following. (i) At room temperature (RT), no functionalization ofAu-free glass occurs, whereas in the case of glasses containing AuNPs, stable linkages form only with amino groups, as inthis condition Au does not bind with either thiol or hydroxyl groups. The RT functionalization with cysteine and cystineconfirms the preferential functionalization through the amino groups, while the -SH groups are oxidized to S-S bridges.(ii) The functionalization with cysteine and cystine, compared at pH = 5, 9, and 12, is shown not to take place at pH = 5and to be hindered by the glass matrix dissolution at pH = 12 (with consequent release of AuNPs), while the best resultsare obtained at pH = 9. (iii) For the effect of reaction temperature, at 4 °C it is possible to obtain a strong Au-Sinteraction, whereas at RT, a weak Au-N linkage is formed. These results should allow production, in a selective way, ofdifferent bonds exhibiting different strengths and, consequently, different release times in solution, with a wide range ofpossible applications (for instance, weak Au-N bonds in the case of drug delivery, strong Au-S bonds in proteinimmobilization).

F. Fantini; E. Ferrari; G. Lusvardi; G. Malavasi; L. Menabue ( 2010 ) - Synthesis and characterization of Ga-containing silicate based sol-gel and mesoporous sol-gel bioactive glasses loaded with curcumin - Atti del XXXVIII Congresso Nazionale di Chimica Inorganica - Società chimica italiana Trieste ITA) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

1.Introduction Silicate based bioactive glasses are synthesized with the aim to obtain materials usable as bone fillers for orthopedic and maxillo facial surgery1. The studied glasses are sol-gel and mesoporous sol-gel based on molar composition 15CaO-5P2O5-80SiO2 modified with Ga2O3; moreover, curcumin was loaded on these glasses. In fact, these materials may be also used as vehicles for the release of metal ions (Ga with anti-bacterial and anti-cancer properties2) and bio-molecules (curcumin, an anti-oxidant and anti-cancer agent3). 2.Results and Discussion Different techniques (UV-Vis, XRD, SEM, NMR, DTA, AE, ICP) are used to characterize glasses, the absorption and release of curcumin. The results showed that, due to higher external surface, sol-gel glasses adsorb more curcumin with respect to mesoporous; in this last case, another possibility of adsorption is by means of mesoporous, but its diameter is smaller than the dimension of curcumin molecules. The amount of curcumin uptaken is higher for Ga-containing glasses. All these materials, tested in water for 72 hours, show an initial (6 hours) fast and almost complete release of curcumin; afterwards the release is more slow. The amount of curcumin released from Ga-containing glasses is lower than the Ga-free ones. The amount of gallium present in solution is greater for the systems with curcumin, in this way Ga ions in solution could be act as antibacterial and antioxidant agents.

V.Aina; L.Bergandi; F.Bonino; D.Ghigo; G.Lusvardi; G.Malavasi; L.Menabue; C.Morterra ( 2009 ) - Bioactive phospho-silicate glasses containing CaF2: bioactivity test in simulated body fluids and behaviour towards osteoblast cells - Surface-Reactive Biomaterials as Scaffold and Coatings:Interactions with Cells and Tissues - ISTEC-CNR Roma ITA) - n. volume 12 - pp. da 243 a 249 ISBN: 9788880801115 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

In this work it is reported a study, in vitro (DMEM), of some potentially bioactive glasses based on the composition of Bioglass® 45S5 bioactive glass, in which CaF2 substitutes alternatively CaO and Na2O. Using a multi-techniques investigation, it is possible to explain in detail the glasses degradatation and the mechanism of formation of an apatitic layer between inorganic material and biological medium. The behaviour of doped glasses is differs from that proposed by Hench for Bioglass® 45S5 bioactive glass, however, these doped glasses have capability of developing bio-activity.A preliminary cellular test is also performed in view of a potential clinical application

V.Aina; G.Lusvardi; G.Malavasi; L.Menabue; C.Morterra ( 2009 ) - Fluoride-containing bioactive glasses: surface reactivity in simulated body fluids - ACTA BIOMATERIALIA - n. volume 5 - pp. da 3548 a 3562 ISSN: 1742-7061 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The issue of the contribution of the addition of F to glass bioactivity is not well resolved. This work reports on the surface reactivity in different solutions (DMEM and Tris) for some potentially bioactive glasses based on the composition of 45S5 glass, in which CaF2 is substituted alternately for (part of) CaO and Na2O. The reactivity of F-containing glasses has been compared with that of the reference 45S5 system. The aim of this study is to explain in detail the mechanism of formation of an apatitic crystalline phase at the interface between the inorganic material and simulated biological media. A multi-technique investigation approach proposes a set of reactions involving Ca-carbonate formation, which are somewhat different from that formerly proposed by Hench for 45S5 bioactive glass, and which occur when a F-containing glass surface is in contact with a SBF. The usefulness of IR spectroscopy in recognizing the starting step of apatite (and/or FA) formation with respect to XRD technique is well established here.

G. Lusvardi; G. Malavasi; L. Menabue; V. Aina; C. Morterra ( 2009 ) - Fluoride-contaning bioactive glasses:surface reactivity in simulated body fluid - Ecers, 11th International Conference and Exhibition of the European Ceramic Society - Polish Ceramic Society Cracovia POL) - n. volume 11 - pp. da 109 a 109 ISBN: 9788360958452 ISSN: - [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

The contribution to bioactivity of F-addition to bioactive glasses seems not well resolved. In this work is reported the surface reactivity in different solutions (DMEM and TRIS) of some potentially bioactive glasses based on the composition of 45S5 bioactive glass, in which CaF2 substitutes alternatively (part of) CaO and Na2O, as compared to the reactivity of 45S5 bioactive glass. This study is aimed at explaining in some detail the mechanism and the rapidity of formation of an apatitic crystal phase at the interface between the inorganic material and simulated biological media.Using a multi-technique investigation approach, we propose a set of reactions, involving Ca-carbonates formation, that is somewhat different from that proposed by Hench for 45S5 bioactive glass, and occurs when a F-containing glass surface is contacted with a simulated body solution. The usefulness of IR spectroscopy in recognizing the starting step of apatite (fluoro-apatite) formation, with respect to XRD technique, is well established.

Lusvardi G.; Zaffe D.; Menabue L.; Bertoldi C.; Malavasi G.; Consolo U. ( 2009 ) - In vitro and in vivo behaviour of zinc-doped phosphosilicate glasses - ACTA BIOMATERIALIA - n. volume 5 - pp. da 419 a 428 ISSN: 1742-7061 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The aim of this work was to study the behaviour of zinc-doped phosphosilicate glasses based on Bioglass 45S5. In vitro (in simulated body fluid), the reactivity was analysed by means of inductively coupled plasma spectrometry, environmental scanning electron microscopy–energy-dispersive spectroscopy (ESEM–EDS) and X-ray diffraction. In vivo (a rat implanted with glass), the reactivity and the tissue behaviour were analysed by conventional histology, histochemistry, microradiography and ESEM–EDS. The in vivo behaviour matches that in vitro perfectly; they show comparable glass degradation processes and rates, ruled by the amount of zinc in the glass.The reaction mechanism for the formation of a polymerized silica layer superimposed with a peripheral calcium phosphate layer is clearly substantiated by ESEM–EDS investigations. The crystallization of a biologically active hydroxyapatite (HA) layer is observed in both cases; the in vitro experiment shows the presence of HA after 4 days. IDS Number: 386ZV PMID: 18701362

G. Lusvardi; G. Malavasi; F. Tarsitano; L. Menabue*; M.C. Menziani; A. Pedone ( 2009 ) - Quantitative Structure−Property Relationships of Potentially Bioactive Fluoro Phospho-silicate Glasses - JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL - n. volume 113 - pp. da 10331 a 10338 ISSN: 1520-6106 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this work, the glass transition temperature and chemical durability of bioactive phospho-silicate glasses were experimentally determined and correlated to the structural descriptor Fnet derived from classical molecular dynamics simulations. The replacement of CaF2 for Na2O in the parent glass 45S5 enhances both chemical durability and density, while the replacement of CaF2 for CaO lowers chemical durability. The proposed descriptor, Fnet, provides satisfactorily correlations with glass transition temperature and chemical durability over a wide range of compositions.

Lusvardi, G.; Malavasi, G.; Menabue, L.; Menziani, M.C. ( 2008 ) - A combined experimental-computational strategy for the design, synthesis and characterization of bioactive zinc-silicate glasses - Progress in bioceramics - Trans Tech Publications CHE) - n. volume 377 - pp. da 211 a 224 ISBN: 9780878493951 ISSN: 1013-9826 [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

This review presents a combined experimental-computational strategy for the development of potential bioactive zinc–containing silicate glasses and shows how sound relationships among the structural role of some key elements that appear to control bioactivity can by established and exploitfor rational glass design.

G. Lusvardi; G. Malavasi; M. Cortada; L. Menabue; M. C. Menziani; A. Pedone; U. Segre ( 2008 ) - Elucidation of the Structural Role of Fluorine in Potentially Bioactive Glasses by Experimental and Computational Investigation - JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL - n. volume 112(40) - pp. da 12730 a 12739 ISSN: 1520-6106 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Glasses belonging to the Na2O-CaO-P2O5-SiO2 system and modified by CaF2 substitution for CaO and Na2Oalternatively, were synthesized and characterized experimentally and computationally. The results of moleculardynamics simulations show that fluorine is almost exclusively bonded to modifier cations (Ca and Na) withcoordination number close to 4. A similar mean coordination number value is found in the crystal phasesobtained by means of thermal treatment at fixed temperature. Addition of fluorine increases the polymerizationof silicate tetrahedra by removing modifiers from the siliceous matrix. No appreciable amount of Si-F bondsare detected.

L.Linati; G.Lusvardi; G. Malavasi; L.Menabue; M.C.Menziani; P. Mustarelli; A Pedone;U. Segre ( 2008 ) - Medium-range order in phosphosilicate bioactive glasses: Insights from MAS-NMR spectra, chemical durability experiments and molecular dynamics simulations - JOURNAL OF NON-CRYSTALLINE SOLIDS - n. volume 354 - pp. da 84 a 89 ISSN: 0022-3093 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The medium-range order of phospho-silicate bioactive glasses (with compositions (2 p)SiO2 Æ 1Na2O Æ 1.1CaO Æ pP2O5, in whichp = 0.10, 0.20, 0.26) has been studied by means of a combined-experimental (MAS-NMR, chemical durability measurements) and computational(classical molecular dynamics (MD)) approach. The structural model obtained by MD is showed to be helpful in the interpretationof the NMR spectra. A small amount of Si–O–P link units has been detected in glasses with low P2O5-content, but at high P2O5concentration the percentage of Si–O–P bridges becomes important. However, Qn distributions show that the HP5 (p = 0.20) glass structureis less polymerized with respect to the H (p = 0.10) and HP6.5 (p = 0.26) glasses. These results provide useful explanation of thebehavior of these glasses in water and highlight the influence of the medium-range order on a very important property of potentialbioactive glasses such as the chemical durability.

G. LUSVARDI; MALAVASI G; MENABUE L; MENZIANI M C; PEDONE A; SEGRE U; AINA V; PERARDI A; MORTERRA C; BOCCAFOSCHI F; GATTI S; BOSETTI M; CANNAS M ( 2008 ) - Properties of zinc releasing surfaces for clinical applications - JOURNAL OF BIOMATERIALS APPLICATIONS - n. volume 22 - pp. da 505 a 526 ISSN: 0885-3282 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Two series of glasses of general formula (2-p) SiO21.1Na2OCaOpP2O5xZnO (p = 0.10, 0.20; x = 0.0, 0.16, 0.35, and 0.78) have been analyzed for physico-chem. surface features before and after contact with simulated body fluid, morphol. characteristics, and osteoblast-like cells behavior when cultured on them. The resulted good cell adhesion and growth, along with nonsignificant changes of the focal contacts, allow the authors to indicate HZ5 and HP5Z5 glasses as the ones having optimal ratio of Zn/P to maintain acceptable cell behavior, comparable to the bioactive glass (Bioglass) used as a control; results are also rationalized by means of three-dimensional models derived by mol. dynamic simulations, with decompn. and conversion rates optimized with respect to the parent Hench's Bioglass.

C. Bertoldi; D. Zaffe; U. Consolo; G. Lusvardi; A. Lucchi; L. Menabue ( 2008 ) - Vetri bioattivi con elementi stimolanti l’osteogenesi: primi risultati nel ratto - DOCTOR. OS - n. volume 19 Suppl. 1 - pp. da 41 a 43 ISSN: 1120-7140 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Introduzione e scopo: Numerose composizioni di vetri bioattivi sono state proposte dopo l'iniziale biovetro di Hench presentato negli anni '70. In realtà il range di variazione della composizione di un vetro bioattivo è abbastanza ridotto soprattutto in rapporto ai suoi elementi pesanti si vuole mantenere l'effetto osteoinduttivo. Ciò in particolarmente in rapporto allo zinco che ne costituisce una fase critica sia da un punto di vista chimico che biologico.Un problema manifestato dal vetro di Hench era quello di agire con buona performance ma di esaurire in fretta la sua azione. Scopo della nostra ricerca preliminare è di studiare il comportamento di vetri contenenti zinco a seguito di impianto degli stessi su modelli biologici standardizzati (muscoli paravertebrali e calvaria di ratto) e di confrontarlo con quello conseguito all’innesto del biovetro di Hench. Materiali e metodi: Vetri bioattivi modificati, derivanti dal bio-glass ® 45S5 di Hench sono stati prima testati chimicamente al fluido biologico somulato con spettroscopia al plasma e analisi diffrattometrica X. Impiantati in 10 ratti maschi Sprague Dawley in forma di polvere e cilindri nei muscoli paravertebrali ed in forma di placchette in difetti critici prodotti sulla calvaria. Sono state analizzati a split-back e su calvaria vetri con concentrazioni al 5% e 20% di zinco e vetro di Hench. Gli animali sono stati sacrificati a 30 giorni dall’intervento e sono state eseguite analisi microradiografiche, al microscopio elettronico a scansione ed istologiche. Risulatati: La diffusione degli ioni zinco si dimostrava assolutamente contenuta allo studio spettroscopico e diffrattomentrico mentre clinicamente gli animali non presentavano reazioni patologiche rilevanti all’innesto. I campioni contenenti un maggior contenuto di zinco parevano essere meno soggetti a degradazione rispetto agli altri e le forme granulari erano degradate con maggior velocità rispetto a quelle compatte. La presenza di uno strato positivo alla fosfatasi alcalina in rapporto alla superficie del biovetro assieme alla deposizione di strati di connettivo presumibilmente osteogenico uniformano sostanzialmente il comportamento dei vetri testati ed il loro potenzaile osteogenetico. Conclusione: La presenza di zinco (almeno fino alle concentrazioni testate) nel vetro pare essere inversamente proporzionale alla reattività dello stesso per cui l’utilizzazione di questo ione pare essere funzionale nel regolare i tempi di bioattività dello stesso vetro senza pesare significativamente sulla biocompatibilità degli stessi preparati.

Bertoldi C.; Zaffe D; Lusvardi G.; Consolo U.; Menabue L. ( 2007 ) - Biocompatibilità di nuovi vetri bioattivi contenenti zinco. - Atti XIV Congresso Nazionale del Collegio dei Docenti di Odontoiatria - DOCTOR. OS - n. volume XVIII-4 (Suppl.) - pp. da 163 a 163 ISSN: 1120-7140 [Abstract in rivista (266) - Abstract in Rivista]
Abstract

Vedi allegato

G. Malavasi;G. Lusvardi;A. Pedone;M.C.Menziani;M.Dappiaggi; A. Gualtieri; L. Menabue ( 2007 ) - Crystallization Kinetics of Bioactive Glasses in the ZnO-Na2O-CaO-SiO2 System - JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY - n. volume 111(34) - pp. da 8401 a 8408 ISSN: 1089-5639 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystallization kinetics of Na2OâCaOâ2SiO2 (x ) 0) and 0.68ZnOâNa2OâCaOâ2SiO2 (x ) 0.68, where xis the ZnO stoichiometric coefficient in the glass formula) bioactive glasses have been studied using bothnonisothermal and isothermal methods. The results obtained from isothermal XRPD analyses have showedthat the first glass crystallizes into the isochemical Na2CaSi2O6 phase, whereas the Na2ZnSiO4 crystallinephase is obtained from the Zn-rich glass, in addition to Na2CaSi2O6. The activation energy (Ea) for thecrystallization of the Na2OâCaOâ2SiO2 glass is 193 ( 10 and 203 ( 5 kJ/mol from the isothermal in situXRPD and nonisothermal DSC experiments, respectively. The Avrami exponent n determined from theisothermal method is 1 at low temperature (530 °C), and its value increases linearly with temperature increaseup to 2 at 607 °C. For the crystallization of Na2CaSi2O6 from the Zn-containing glass, higher values of boththe crystallization temperature (667 and 661 °C) and Ea (223 ( 10 and 211 ( 5 kJ/mol) have been foundfrom the isothermal and nonisothermal methods, respectively. The Na2ZnSiO4 crystalline phase crystallizesat lower temperature with respect to Na2CaSi2O6, and the Ea value is 266 ( 20 and 245 ( 15 kJ/mol fromthe isothermal and nonisothermal methods, respectively. The results of this work show that the addition ofZn favors the crystallization from the glass at lower temperature with respect to the Zn-free glass. In fact, itcauses an increase of Ea for the Na diffusion process, determined using MD simulations, and consequentlyan overall increase of Ea for the crystallization process of Na2CaSi2O6. Our results show good agreementbetween the Ea and n values obtained with the two different methods and confirm the reliability of thenonisothermal method applied to kinetic crystallization of glassy systems. This study allows the determinationof the temperature stability field of the crystalline phases with the view of creating a different glass ceramicuseful in the field of bioactive materials.

V. AINA; A. PERARDI; L. BERGIANDI; G. MALAVASI; L. MENABUE; C. MORTERRA; D. GHIGO ( 2007 ) - Cytoxicity of zinc-cotaining bioactive glasses in contact with human osteoblasts - CHEMICO-BIOLOGICAL INTERACTIONS - n. volume 167 - pp. da 207 a 218 ISSN: 0009-2797 [Articolo in rivista (262) - Articolo su rivista]
Abstract

potential clinical application, we have investigated whether zinc-containing 45S5 (HZ) glasses might be cytotoxic for human rs on Bioactive glasses such as Hench’s 45S5 have applications to tissue engineering and bone repair: the insertion of zinc has been proposed to improve their bone-bonding ability and to slacken their dissolution in extracellular body fluids. In view of a MG-63 osteoblasts. In our experimental conditions, after 24 h of incubation HZ glasses released significant amounts of Zn2+ and induced in MG-63 cells release of lactate dehydrogenase (index of cytotoxicity) and the following indexes of oxidative stress: (i) accumulation of intracellular malonyldialdehyde, (ii) increased activity of pentose phosphate pathway, (iii) increased expression of peheme oxygenase-1, (iv) increased activity of Cu,Zn-superoxide dismutase, (v) decreased level of intracellular thiols. These effects were inversely related to the zinc content of glass powders, were mimicked by ZnCl2 solutions and were prevented by either metal chelators (EDTA, NTA) or the antioxidant ascorbate, suggesting that Zn2+ released fastly from HZ glasses can cause MG-63 cell damage via an oxidative stress. This work highlights the importance of designing Zn-containing bioactive glasses without cytotoxic effects and gives supplementary information about the prooxidant role of zinc in living systems.

G. Lusvardi; G. Malavasi; L. Menabue; MC Menziani; A. Pedone; U. Segre ( 2007 ) - Density of multicomponent silica-based potential bioglasses: Quantitative structure-property relationships (QSPR) analysis - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 27(2-3) - pp. da 499 a 504 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The results of a quantitative structure-property relationships (QSPR) analysis of multicomponent silica-based potential bioglasses (containing Na2O, CaO, P2O5 and/or ZnO) are here presented. A quantitative model explaining the variation of the density data measured for series of glasses with different compositions has been obtained by means of a structural descriptor derived from molecular dynamics (MD) simulations. A descriptor able to rationalize the variation in density caused by the overall packing degree of the structural units in the glasses examined has been defined. It is worth noting that the descriptor used allows the fitting of glasses with different composition (presence-absence Of P2O5, ZnO, Na2O and CaO) in the same correlation. The validity of the QSPR approach, which has recently been introduced for the rationalization and prediction of the technology-related properties of a series of complex multicomponent glasses, is confirmed by this work on a larger series of glasses of various compositions. (c) 2006 Elsevier Ltd. All rights reserved.

C. Caselli; G. Lusvardi; G. Malavasi; L. Menabue; P. Miselli ( 2007 ) - Multitechnique approach to V-ZrSiO4 pigment characterization and synthesis optimization - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 27(2-3) - pp. da 1743 a 1750 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The synthesis of blue-turquoise V-ZrSiO4 Pigment from an aqueous solution of Na2O center dot 2.5SiO(2)center dot 5H(2)O (soluble glass) and the citrate complexes of zirconium and vanadium was investigated as a function of V2O5 contents, mineralizers (NaF and/or LiNO3) addition and thermal cycle. Blue V-ZrSiO4 was obtained without mineralizers addition for the (ZrO2)(SiO2)(V2O5)(0.09) composition; QPA analysis shows that a thermal cycle 3 h long, T-max = 800 degrees C, can lead to a 78.0 wt.% of ZrSiO4. The addition of mineralizers gave rise to 73.0 wt.% of ZrSiO4 for the (ZrO2)(SiO2)(NaF)(0.16)(V2O5)(0.09)(LiNO3)(0.09) composition and a thermal cycle 2 h long, T-max = 800 degrees C. LiN03 can favour both ZrSiO4 formation and a fairly blue colour, up to LiNO3 = 0.09 moles; NaF seems effective on ZrSiO4 formation only when mixed with LiNO3 through the formation of LiF HT-XRD analysis of this composition agrees with QPA results at the corresponding temperature; ZrSiO4 was present (64.0 wt.%) at 730 degrees C and good colour parameters were obtained. (c) 2006 Elsevier Ltd. All rights reserved.

F. ANDREOLA; E. CASTELLINI; G. LUSVARDI; L. MENABUE; M. ROMAGNOLI ( 2007 ) - RELEASE OF IONS FROM KAOLINITE DISPERSED IN DEFLOCCULANT SOLUTIONS. - APPLIED CLAY SCIENCE - n. volume 36 - pp. da 271 a 278 ISSN: 0169-1317 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Chem. investigations have been performed on deflocculated suspensions of kaolinite previously treated with two widely employed dispersants: sodium hexametaphosphate (NaHMP) and sodium disilicate (NaDIS). F. Andreola et al. (2006) showed remarkable differences in the rheol. behavior between untreated and treated samples. The release of ions by kaolinite dispersed in deflocculant solns. results strongly affected by the nature of the treatment. The chem. anal. of the soln. phase sepd. from the suspensions of treated and untreated kaolinite provides relevant information about the deflocculation mechanism of HMP and DIS and gives reason of the obsd. differences in the rheol. responses.

G. LUSVARDI; G.MALAVASI; A.PEDONE; L.MENABUE; M.C. MENZIANI; V.BOLIS; M. BORSETTI; F.BOCCAFOSCHI; M.CANNAS ( 2006 ) - Cell configuration for focal adhesions in cells seeded onto Zinc-doped silicate-bioglasses - Ceramic, Cells and Tissues; Materials for Scaffolding of Biologically engineered systems-Interface and Interactions on a Nanoscale - CNR Faenza FAENZA ) - pp. da 166 a 170 ISBN: 9788880800712 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

G.Lusvardi; G.Malavasi; L.Menabue; M.C. Menziani; A.Pedone; D.Zaffe ( 2006 ) - Physico-chemical characterization and in vivo evaluation of zinc-glasses biocompatibility - Abstract book - EUCHEMS Budapest HUN) - n. volume 1 - pp. da 164 a 164 ISBN: 9789639319615 ISSN: - [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

Study of soda-lime-phosphosilicate glasses based on Bioglass® and modified by zinc. "In vitro"(SBF) bioactivity was investigated through apatite forming ability and through a preliminary "in vivo" study. Zinc improves chemical durability but does not inhibit the apatite formation; a mixed-metal (Ca-Zn) phosphate-based crystalline layer is identified on the surface of HP5Z5. The improvement of the observed chemical durability can also be rationalized by Molecular Dynamics simulations

F. Andreola; M.C. Romagnoli; E. Castellini; G. Lusvardi; L. Menabue ( 2006 ) - Role of the surface treatment in the deflocculation of kaolinite - JOURNAL OF THE AMERICAN CERAMIC SOCIETY - n. volume 89 (3) - pp. da 1107 a 1109 ISSN: 0002-7820 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Suspensions of untreated and properly treated Na-exchanged kaolinite have been subjected to rheological investigations using sodium hexametaphosphate (NaHMP) or sodium disilicate (DIS) as deflocculants. The treatment of the clay consisted of a 24 h contact with solutions of NaHMP or DIS and separation of the resulting solid phase. This was then used to form the suspensions subjected to the rheological measurements. The results indicate that the dispersion ability of each deflocculants is remarkably influenced by the type of treatment. In particular, with respect to the untreated kaolinite, the efficiency of DIS is dramatically increased when the clay has been previously treated with a NaHMP solution. On the other hand, a decrease in the dispersant ability of NaHMP is observed from the untreated kaolinite to the one previously treated with DIS.

G. Lusvardi; G. Malavasi; L. Menabue; M. C. Menziani;A.Pedone; U. Segre ( 2005 ) - A Computational Tool for the Prediction of Crystalline Phases Obtained from Controlled Crystallization of Glasses - JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL - n. volume 109 - pp. da 21586 a 21592 ISSN: 1520-6106 [Articolo in rivista (262) - Articolo su rivista]
Abstract

An automatic tool (named CLUSTER) for the prediction of the most probable crystal phases that can separatefrom glasses has been developed. The program analyzes the output of molecular dynamics simulations ofglasses or glass ceramics, systematically sampling the ratios of the ions in different portions of the simulationbox and comparing them to the stoichiometric ratio of compositionally equivalent crystalline phases retrievedfrom a crystal structure database. The efficacy of the similarity index elaborated has been judged by comparingthe results obtained with the crystal phases identified by XRD analysis after thermal treatment in a series ofmulticomponent potential bioactive glasses and glass ceramics for which the advantages of rational-designederosion-controlled release is straightforward.

L. LINATI; G. LUSVARDI; G. MALAVASI; L. MENABUE; MC MENZIANI; P. MUSTARELLI; U. SEGRE ( 2005 ) - Qualitative and quantitative structure-property relationships analysis of multicomponent potential bioglasses - JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL - n. volume 109 - pp. da 4989 a 4998 ISSN: 1520-6106 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The results of a qualitative and quantitative structure-property relationships analysis of multicomponent potential bioglasses of composition (2 - y)SiO(2)center dot 1Na(2)O center dot 1.1CaO center dot yP(2)O(5)center dot xZnO (x = 0, 0.16, 0.35, 0.78 and y - 0. 10, 0.20, 0.36) are presented. Quantitative models are obtained by means of structural descriptors derived by molecular dynamics simulations and experimental data measured for density, thermal analysis, 21 Si and IT magic angle spinning NMR, and chemical durability in water. Analysis of the crystal species obtained upon glass crystallization helped in the rationalization of the structural role of the different components. Finally, glass surface characterization with scanning electron microscopy, transmission electron micrsocopy, and X-ray diffraction after soaking in acellular simulated body fluid demonstrated the in vitro bioactivity of the newly obtained 1.80SiO(2)center dot 1Na(2)O center dot 1.1Ca center dot 0.20P(2)O(5)center dot 0.16ZnO (HP5Z5) glass, corresponding to x = 0. 16 and y = 0.20.

E. Castellini; G. Lusvardi; G. Malavasi; L. Menabue ( 2005 ) - Thermodynamic aspects of the adsorption of hexametaphosphate on kaolinite - JOURNAL OF COLLOID AND INTERFACE SCIENCE - n. volume 292 - pp. da 322 a 329 ISSN: 0021-9797 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The adsorption of hexametaphosphate ion, an important deflocculant used in the ceramic industry, from aqueous solutions onto kaolinite has been studied at different temperatures. The adsorption isotherm follows the Langmuir model: the thermodynamic parameters Delta G(ads)(0), Delta H-ads(0) and Delta S-ads(0) as were calculated and found to be consistent with an interaction model involving the formation of an inner-sphere complex between HMP and aluminol groups. Also, the dependence of the adsorption behavior on the kaolinite volume fraction has been studied and discussed in term of association processes between the clay particles.

LUSVARDI G; G.MALAVASI; L. MENABUE; M.C.MENZIANI; U.SEGRE; V.AINA; C.MORTERRA; M.F.CANNAS ( 2005 ) - Zinc-releasing silicate-bioglasses modulated Bone Cells Activity - Trans. for SFB Meeting [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Two series of glasses of general formula (2-p) SiO21.1Na2OCaOpP2O5xZnO ( p ¼ 0.10, 0.20; x ¼ 0.0, 0.16, 0.35, and 0.78) have been analyzed for physico-chemical surface features before and after contact with simulated body fluid, morphological characteristics, and osteoblastlike cells behavior when cultured on them. The resulted good cell adhesion and growth, along with nonsignificant changes of the focal contacts, allow the authors to indicate HZ5 and HP5Z5 glasses as the ones having optimal ratio of Zn/P to maintain acceptable cell behavior, comparable to the bioactive glass (Bioglass) used as a control; results are also rationalized by means of three-dimensional models derived by molecular dynamic simulations, with decomposition and conversion rates optimized with respect to the parent Hench’s Bioglass

G. LUSVARDI; G. MALAVASI; L. MENABUE; M.C. MENZIANI; U. SEGRE; M.M. CARNASCIALI; A. UBALDINI ( 2004 ) - A combined experimental and computational approach to (Na2O)(1-x) (CaO) (ZnO)(x)2SiO2 glasses characterization - JOURNAL OF NON-CRYSTALLINE SOLIDS - n. volume 345 - pp. da 710 a 714 ISSN: 0022-3093 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Insight into the Zn structural role in a series of glasses of composition (Na2O)(1-x) (.) CaO (.) (ZnO)(x) (.) 2SiO(2) (x = 0, 0.2, 0.6 and 1) has been obtained by density measurements, analysis of the crystals separated from the glasses, micro-Raman spectra and molecular dynamics simulations. We found that Zn acts as a weak tetrahedral network former independent of the glass Na content.

G. LUSVARDI; G. MALAVASI; L. MENABUE; MC MENZIANI; U. SEGRE ( 2004 ) - CaO and ZnO in soda-silicate glasses: a molecular dynamics simulation study and experimental characterization - Advances in Sciences and Technology - Techna Group srl FAENZA ITA) - n. volume 42 - pp. da 127 a 134 ISBN: 9788886538459 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

CaO and ZnO in soda-silicate glasses: a molecular dynamics simulation study and experimental characterization

E. Ferrari; L. Menabue; M. Saladini ( 2004 ) - Characterization and metal affinity of Tirofiban, a pharmaceutical compound used in acute coronary syndromes - BIOMETALS - n. volume 17 - pp. da 145 a 155 ISSN: 0966-0844 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal and molecular structure of Tirofiban [ N-(n-butanesulfonyl)-O-(4-(4-piperidinyl)-butyl)-(S)-tyrosine] is here reported. In the solid state the carboxylic group is in the anionic form while the piperidine molecule appear in the protonated form. By H NMR spectroscopy and potentiometric study three pK(a) are found: pKa(COOH) = 3.1(1), pKa(NHPIP) = 11.6(1) and pKa(NHSO2) = 13.8(1). The complexing ability of Tirofiban towards various metal ions (Cu(II), Ni(II), Co(II), Cd(II), Pb(II), Zn(II) and Ca(II)) is also determined by means of potentiometric studies. The prevailing species are [M(TirH)(2)](2+) where the ligand coordinates the metal ion through carboxylic group, while the piperidine nitrogen is still protonated. The great stability of these complexes may be due to the presence of hydrogen bond interactions, as well as the formation of stacking interactions involving the phenyl ring of the tyrosine residue.

S. Braccini; C. Leonelli; G. Lusvardi; G. Malavasi; L. Menabue ( 2004 ) - In vitro evaluation of zirconia nanopowders - bioceramics 16 - Trans Tech Publications Uetikon CHE) - KEY ENGINEERING MATERIALS - n. volume 254-2 - pp. da 899 a 902 ISSN: 1013-9826 [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

ZrO2 is used for a long time as biomaterial. Nanopowders of ZrO2 are prepared via a microwave assisted hydrothermal synthesis and morphological studies carried out by TEM. The powders are tested in vitro and this test does not alter the dimension of the particles.

Lusvardi, G.; Malavasi, G.; Menabue, L.; Menziani, M.C.; Segre, U. ( 2004 ) - Synthesis and in vitro studies of phosphosilicate glasses doped with cerium and zinc oxides - JOURNAL OF APPLIED BIOMATERIALS & BIOMECHANICS - n. volume 2 - pp. da 212 a 212 ISSN: 1722-6899 [Abstract in rivista (266) - Abstract in Rivista]
Abstract

Glasses based on the Bioglass, formula and doped by the addn. of CeO2 (1.5-13.5%) and ZnO (5-20%) were studied. The addn. if small oxide quantities (1.5% for CeO2 and 5-10% for ZnO) did not significantly alter the ability of the in vitro apatite formation on the glass surface. After 15 days, a mixed-metal (Ca-Zn) or (Ca-Ce) phosphate-based layer was identified. High metal contents improved the chem. durability of the glass, the bioactivity was strongly inhibited and there were no hints of apatite formation obsd. even after prolonged soaking in SBF. The SiO2, 39.4; Na2O, 22.6; CaO, 22.6; P2O5, 10.4; ZnO, 5.0% glass compn. seems to demonstrate an optimal ratio of Zn/P to improve the glass strength and simultaneously yield a Ca/P ratio able to preserve rapid apatite formation.

Lusvardi G.; Zaffe D.; Bertoldi C.; Malavasi G.; Menabue L.; Menziani M.C.; Pedone A. ( 2004 ) - Vetri bioattivi contenenti zinco: comportamento in viotro ed in vivo - Congresso nazionale Biomateriali - Società chimica Italiana, Gruppo interdivisionale biomateriali Napoli ITA) - n. volume Volume unico [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

Vedi allegato

G. Lusvardi; G. Malavasi; L. Menabue; M. Saladini ( 2003 ) - Characterization and thermal behavior of fluoroapatite and Ti-alloy for orthopedic implants - Advances in Science and Technology - Techna Group srl FAENZA ITA) - n. volume 41 - pp. da 187 a 194 ISBN: 9788886538435 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

Characterization and thermal behaviour of fluoroapatite and Ti-alloy for orthopedic implants

Leonelli, C.; Lusvardi, G.; Malavasi, G.; Menabue, L.; Tonelli, M. ( 2003 ) - Synthesis and characterization of cerium-doped glasses and in vitro evaluation of bioactivity - JOURNAL OF NON-CRYSTALLINE SOLIDS - n. volume 316 - pp. da 198 a 216 ISSN: 0022-3093 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The results of preparation, characterization and in vitro bioactivity evaluation of phosphosilicate glasses based on Bioglass(R) 45S5 (SiO2 45; Na2O 24.5; CaO 24.5; P2O5 6 wt%) doped during melting with (1.5-13.5 wt%) cerium dioxide (CeO2), has been reported. The choice of cerium was related to its low toxicity associated with bacteriostatic properties; cerium-doped bioactive glasses could be useful when implantation concerns local infected areas. The maximum value that permitted forming a homogeneous glass was 13.5 wt% and enabled us to get a better insight into CeO2 effect on the chemical behaviour of glasses. The as-quenched glasses were characterized by means of magnetic and spectroscopic measurements that revealed the prevailing presence of cerium (III). The bioactivity of the glasses was tested by soaking them in a simulated body fluid at 37 degreesC, under continuous stirring. ICP measurements were carried out for ion concentration determinations and the solution/glass interface was investigated by scanning electron microscopy equipped with energy dispersive analyzer (SEM/EDS technique) to check morphological modifications; the solids were investigated by means of X-ray powder diffraction and IR techniques. The results indicated that at low cerium content the glass degradation and repolymerization gave rise to an internal silicon-based layer and an external calcium-phosphate-based layer formed on the glass surface; high cerium content retards the glass degradation and gave rise to ceriumphosphate layer instead of calcium one. The cerium was never found in solution. For the reacted glasses, in the external layer, at 10% and 13.5% CeO2 contents the molar ratio Ca/P were approximate to1 and 0.8 respectively and the molar ratio Ce/P was approximate to0.3 in both cases. On the surface of the glasses with the highest cerium content it could distinguish new regular aggregates mainly formed by cerium and phosphate (Ce/Papproximate to3.5, Ca/Papproximate to0.6). In the cerium-free glass and with low cerium content (1.5 wt%) the calculated Ca/P ratio was 1.67, as calculated for pure hydroxyapatite. At low cerium content (BG-1.5 Cc) the glass behaviour was strictly similar to that of Bioglass(R) 45S5. (C) 2003 Elsevier Science B.V. All rights reserved.

G. Lusvardi; G. Malavasi; L. Menabue; M.C. Menziani ( 2003 ) - Zinc addition to sodium-calcium-silicate bioglasses. Theoretical vs experimental results - Advances in Science and Technology - Faenza Ed. FAENZA ITA) - n. volume 36 - pp. da 91 a 98 ISBN: 9788886538381 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

The glass composition Na2O•CaO•2SiO2 was modified upon addition of ZnO to obtain the series of glasses Na2O•CaO•(2-x)SiO2•xZnO (x=0.15 and 0.19), where x= 0.19 is the maximum zinc content which does not produce phase separation. The glasses were investigated by means of density and thermal measurements (glass transition, Tg, and crystallisation, Tc, temperature); moreover the phases separated upon crystallisation were identified. The results of molecular dynamics (MD) simulations combined with the analysis of the crystal structure of the main phases separated [(Na4Ca4(SiO3)6 and Na2ZnSiO4)] provide insight into the structural role of zinc in the glass network, its limits of solubility and its effect on the short- and medium-range order of the glass structure.

M. SALADINI; MENABUE L; FERRARI E ( 2002 ) - Binding ability of sialic acid toward biological and toxic metal ions. NMR, potentiometric and spectrophotometric study. - Kluwer Academic Publishers:Journals Department, PO Box 322, 3300 AH Dordrecht Netherlands:011 31 78 6576050, EMAIL: frontoffice@wkap.nl, kluweronline@wkap.nl, INTERNET: http://www.kluwerlaw.com, Fax: 011 31 78 6576254 ) - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 88 - pp. da 61 a 68 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The binary complexes of 5-amino-3,5-dideoxy-D-glycero-D-galactononulosic acid (NANA), commonly called N-Acetyl Neuraminic Acid, formed with biological metal ions such as Co(II) and Cu(II) and toxic metal ions such as Cd(II) and Pb(II) are investigated in aqueous solution by means of potentiometry, UV and NMR spectroscopy. The corresponding ternary systems with 2,2’-bipyridine are studied in aqueous solution by potentiometry and UV spectroscopy.NANA co-ordinates all metal ions, in both binary and ternary systems trough carboxylic group (protonated or deprotonated according to pH condition), pyranosidic ring oxygen and glycerol chain alcoholic hydroxy groups. The prevailing species in the pH range 2-7 are [M(NANA)2] type, their stability constants are greater than those of simple carboxylate complexes. Over pH 7 the species [M(NANA)2OH]- are also formed, but they don’t prevent the precipitation of metal hydroxides. This work provides information on the solution state chemistry of NANA in presence of bivalent metal ions; its great affinity for Cd(II) and Pb(II) toxic metals, near physiological condition, and the relatively high stability of the complex species found may account also for toxicity mechanism.

E. Ferrari; L. Menabue; M. Saladini ( 2002 ) - Characterization and Metal affinity of tyrofiban®, a pharmaceutical compound used in acute coronary syndromes - Atti del XXX Congresso nazionale della divisione di Chimica Inorganica - xx Modena ITA) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

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M. Saladini; E. Ferrari; L. Menabue ( 2002 ) - Co-ordination of transition metal ions by galactaric acid: a potentiometric and spectroscopic study - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 92 - pp. da 121 a 127 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A solution study on the ability of galactaric acid [GalaH(2), HOOC(CH)(4) COOH] in the complexation of biological metal ions such as Co(II) and Ni(II) and toxic metal ions such as Cd(II), Pb(II) and Hg(II), is reported. The stability constants of the complex species are determined by means of potentiometric measurements. Galactaric acid behaves as chelate ligand through carboxylic oxygen and alpha-hydroxy group towards Co(II) and Ni(II), while in the Pb(II) and Cd(II) containing system it co-ordinates the metal ion with carboxylic oxygen and two alcoholic hydroxy groups. The prevailing species at acidic or neutral pH is [MGala] which is also isolated in the solid state and characterized by means of IR spectroscopy. On increasing pH, the [MGalaH_(1)](-) species is also formed where the co-ordinated OH group undergoes deprotonation in all metal ion complexes except those with Hg(II), where the co-ordination of hydroxide ion is suggested as the precipitation of the metal hydroxide occurs at pH 7. (C) 2002 Elsevier Science Inc. All rights reserved.

Lusvardi, G.; Menabue, L.; Malavasi, G. ( 2002 ) - In vitro characterisation of phosphosilicate and silicate glasses doped with zinc oxide - MATERIALS ENGINEERING - n. volume 13 - pp. da 79 a 88 ISSN: 1120-7302 [Articolo in rivista (262) - Articolo su rivista]
Abstract

It has been shown for various types of glasses and glass-ceramic that the essential condition for them to bond to living bone is the formation of an apatite layer on their surface in the body. Here, the in vitro bioactivity of phosphosilicate and silicate glasses doped with zinc ion has been evaluated. The bioactivity of the glasses was tested by soaking them into a simulated body fluid (SBF) at 37. The soln./glass interface was investigated by SEM to check morphol. modifications: the apatite layer formation was monitored by means of XRD and IR measurements. The degrdn. kinetics of doped glasses has been decelerated. Zinc ion was detected on the reacted surface and its simultaneous presence with calcium and phosphorous atoms could indicate a formation of a mixed zinc-calcium-contg. phase.

Leonelli, C.; Lusvardi, G.; Menabue, L.; Tonelli, M. ( 2002 ) - Preliminary experiments of in situ atomic force microscopy observation of hydroxyapatite formation on bioactive glass surface - JOURNAL OF THE AMERICAN CERAMIC SOCIETY - n. volume 85 - pp. da 487 a 489 ISSN: 0002-7820 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper demonstrates the use of atomic force microscopy (AFM) to image the bioactivity of phosphate glasses that are well-known to react rapidly in simulated body fluid. The present study demonstrates that the hydroxyapatite (HAP) crystalline layer found via AFM in the examined samples coincides with that identified using scanning electron microscopy. Moreover, the effect of a notorious bacteriostatic cation-tetravalent cerium, Ce(IV)-on the kinetics of the HAP layer is investigated in CeO2-doped bioactive glasses.

G. Lusvardi; L. Menabue; M. Saladini ( 2002 ) - Reactivity of biological and synthetic hydroxyapatite towards Zn(II) ion, solid-liquid investigations - Kluwer Academic Publishers:Journals Department, PO Box 322, 3300 AH Dordrecht Netherlands:011 31 78 6576050, EMAIL: frontoffice@wkap.nl, kluweronline@wkap.nl, INTERNET: http://www.kluwerlaw.com, Fax: 011 31 78 6576254 ) - JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE - n. volume 13 - pp. da 91 a 98 ISSN: 0957-4530 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction of biological and synthetic hydroxyapatite Ca-5(PO4)(3)OH (HAP) with Zn2+ ions is investigated as a function of Zn2+/Ca2+ molar ratio, time, temperature and electrolyte type (NaCl, NaHCO3, Na2HPO4) by means of pH, pZn, pCa measurements, in aqueous solution. Biological powdered HAP invariably affords an almost quantitative reaction, while Zn2+ precipitated only partially by reaction with cubelets of biological HAP. Using powdered biological HAP and synthetic HAP (dried at 100 degreesC), the reaction with Zn2+ ion is fast and takes place without addition of precipitating anion; synthetic HAP (dried at 1000 degreesC) reacts if free phosphate ions are present. The solid phases separated after different reaction times are investigated by means of X-ray diffraction (XRD), IR, SEM techniques and elemental analysis (C,H,N). The solid phases contain Zn-3(PO4)(2) . 4H(2)O (Hopeite) at the beginning of reaction and CaZn2(PO4)(2) . 2H(2)O (Scholzite) at the equilibrium.

G. Lusvardi; G. Malavasi; L. Menabue; M. Saladini ( 2002 ) - Removal of cadmium ion by means of synthetic hydroxyapatite - WASTE MANAGEMENT - n. volume 22 - pp. da 853 a 857 ISSN: 0956-053X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction behaviour of synthetic hydroxyapatite [Ca-10(PO4)(6)(OH)(2)] (HAP) toward cadmium ion was investigated for the Cd/Ca molar ratio in the range 1-0.005, by means of ions, pH measurements and XRD, SEM, IR techniques. The reaction behaviour between HAP and cadmium ion could be explained by a formation of an amorphous phase and/or a sorption mechanism. (C) 2002 Elsevier Science Ltd. All rights reserved.

Lusvardi, G.; Malavasi, G.; Menabue, L.; Menziani, M.C. ( 2002 ) - Synthesis, characterization, and molecular dynamics simulation of Na2O-CaO-SiO2-ZnO glasses - JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL - n. volume 106 - pp. da 9753 a 9760 ISSN: 1520-6106 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The glass of composition Na2O.CaO.2SiO(2) was modified upon addition of ZnO to obtain the series of glasses Na2O.CaO.2SiO(2).xZnO (x = 0.17, 0.34, 0.68), where x = 0.68 is the experimentally determined maximum zinc content that does not produce phase separation. The glasses were investigated by means of density and thermal measurements (,(glass-transition and crystallization temperatures); moreover, the phases separated upon crystallization were identified. The results of molecular dynamics (MD) simulations combined with the analysis of the crystal structure of the main phases separated (Na2Ca(SiO3)(2) and Na2ZnSiO4) provided insights into the structural role of zinc and its effect on the short- and medium-range order of the glass structures.

M. Saladini; L. Menabue; E. Ferrari; D. Iacopino ( 2001 ) - Amide group coordination to the Hg2+ ion. Potentiometric, 1H NMR and structural study on Hg2+-N-protected amino acid systems - JOURNAL OF THE CHEMICAL SOCIETY. DALTON TRANSACTIONS - n. volume non previsto - pp. da 1513 a 1519 ISSN: 1472-7773 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The binary complexes of Hg2+ formed by N-carbonyl and N-sulfonyl amino acids, which are ligands containing peptide and sulfonamide groups respectively, are investigated in aqueous solution by H-1 NMR, UV spectroscopy and potentiometry. The corresponding ternary systems with 2,2'-bipyridine are studied in aqueous solution by potentiometry and in DMSO solutions by H-1-NMR. All the amino acids behave as simple carboxylate ligands at acid pH, while, around neutrality, N-p-tolylsulfonylglycine (tsglyH(2)), N-p-tolylsulfonyl-beta -alanine (ts-beta -alaH(2)) and N-2-nitrophenylsulfonylglycine (NO(2)psglyH(2)) switch to dianionic N,O-bidentate chelating ligands due to the involvement of the deprotonated amide nitrogen as an additional donor site. The Hg2+ ion is ineffective in promoting peptide nitrogen deprotonation in N-benzoylglycine (bzglyH). The binary and ternary species formed in aqueous solution and their stability constants are determined and compared with those of the homologous complexes of Pd2+, Cu2+, Cd2+ and Pb2+. The molecular structure of [Hg(bpy)(2)(NO2-psgly-N,O)].0.5H(2)O is determined by X-ray crystallography. It represents a rare example of Hg2+ N,O coordination by an amino acid molecule. In the complex Hg2+ shows a distorted octahedral environment with a N5O donor set. Four nitrogen atoms are derived from the two bpy ligands, while the oxygen and the fifth nitrogen are from the NO2-psgly dianion. New information on the solution and solid state chemistry of Hg2+ with ligands of biological interest is provided which may be of great relevance in understanding the mechanism of metal toxicity.

C. LEONELLI; G. LUSVARDI; M. MONTORSI; MC MENZIANI; L. MENABUE; P. MUSTARELLI; L. LINATI ( 2001 ) - Influence of small additions of Al2O3 on the properties of the Na2O center dot 3SiO(2) glass - JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL - n. volume 105 - pp. da 919 a 927 ISSN: 1520-6106 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Changes in the structural properties of sodium alumine-silicate glasses of general formula Na2O . xAl(2)O(3). (3-x)SiO2 were investigated as a function of Al2O3 concentration. The experimental evidences provided by density, elastic modulus, glass chemical resistance measures, Si-29 and Al-27 MAS NMR investigations were complemented by molecular dynamics simulations. While neither of the experimental techniques or computational investigation utilized in this study were able to furnish unequivocable responses for the rationalization of the measured properties of sodium alumine-silicate glasses, the synergistic application of experimental and computational techniques showed that the anomalies observed in bulk properties like density and elastic modulus find their origin in medium-range structural features.

M. Saladini; L. Menabue; E. Ferrari ( 2001 ) - Sugar complexes with metal(2+) ions: thermodynamic parameters of associations of Ca2+, Mg2+ and Zn2+ with galactaric acid - CARBOHYDRATE RESEARCH - n. volume 336 - pp. da 55 a 61 ISSN: 0008-6215 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A solution study on the complex ability of galactaric acid (GalaH(2)) for complexation with Ca2+, Mg2+ and Zn2+ ions is reported. The stability constants of the complex species are determined by means of potentiometric measurements. From the dependence of stability constants on temperature, the DeltaH degrees and DeltaS degrees values are also determined. The formation of the complex species is an endothermic process and DeltaH degrees and DeltaS degrees values suggest a chelate coordination mode of galactaric acid involving carboxylic oxygen and a-hydroxylic group. The prevailing species at acidic or neutral pH is [MGala] (M = Ca2+, Mg2+, Zn2+) which is also isolated in the solid state and characterised by means of IR spectroscopy. On increasing pH, the [MGalaH -(1)](-) species is also formed, where the coordinated OH group undergoes deprotonation. (C) 2001 Elsevier Science Ltd. All rights reserved.

M. Saladini; D. Iacopino; L. Menabue ( 2000 ) - Metal(II) binding ability of a novel N-protected amino acid. A solution-state investigation on binary and ternary complexes with 2,2 '-bipyridine - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 78 - pp. da 355 a 361 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The binary and ternary systems 2,2'-bipyridine (bpy)-M(II)-NO(2)psglyH(2) (M(II) =Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II); NO(2)psglyH(2) =N-(2-nitrophenylsulfonyl)glycine) were investigated in aqueous solution by means of potentiometry and electron spectroscopy in order to identify the type, number and stability of the complex species as a function of pH and metal-to-ligand molar ratio. The aim is to evaluate the effect of a substituent on the phenyl ring of the N-sulfonyl amino acids on their coordination properties. The prevailing species in the binary systems is the [ML] (M=Co(II), Ni(II), Cu(II), Cd(II), Pb(II)) where the amino acid molecule is in the dianionic form and coordinates the metal ion through both carboxylic oxygen and deprotonated sulfonamidic nitrogen, while in the Mn(II) and Zn(II)-containing binary system the only complex species found are those with the amino acid in the monoanionic form. In the ternary 2,2'-bipyridine-containing systems the chelating coordination mode of the dianionic amino acid is maintained with M(II) = Co(n),Ni(II), cu(n), Cd(II), Pb(II) and the addition of the aromatic base also enables the Zn(II) ion to substitute for the sulfonamide nitrogen-bound hydrogen of NO(2)psglyH(2). (C) 2000 Elsevier Science Inc. All rights reserved.

M. Saladini; M. Candini; D. Iacopino; L. Menabue ( 1999 ) - Binding ability of aldaric acid toward metal(II). X-ray study and solution state investigation on Cu(II)-galactaric acid system and its 2,2 '-bypiridine adduct - INORGANICA CHIMICA ACTA - n. volume 292 - pp. da 189 a 197 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The interaction of Cu2+ with galactaric acid leads to the formation, at acidic pH, of the complex species [CuGala] (Gala = galactaric dianion), while at physiological pH the prevailing species is [Cu(GalaH(-2))](2-) where the carbohydrate acts as chelating agent toward the metal ion through the carboxylic groups and the deprotonated ct-hydroxylic oxygens. The crystal structures of galactaric acid (1) and of the ternary complex [CuGala(bpy)](n). 2nH(2)O (2) (bpy = 2,2'-bipyridine) are also reported. A comparison of the coordinative behavior of galactaric acid and other aldonic and alduronic acids is also discussed. (C) 1999 Elsevier Science S.A. All rights reserved.

A. BONAMARTINI CORRADI; G. LUSVARDI; L. MENABUE; M. SALADINI; P. SGARABOTTO ( 1999 ) - Coordination properties of N-p-tolylsulfonyl-L-glutamic acid toward metal(II) - Part 1. Crystallographic study on Zn-II and Cd-II complexes - POLYHEDRON - n. volume 18 - pp. da 1975 a 1982 ISSN: 0277-5387 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A series of compounds of N-p-tolylsulfonyl-L-glutamic acid with divalent Cu, Zn and Cd are synthesized and characterized. For the complexes [Zn(tsgluO)(H2O)(2)]. H2O (1), [Cd-2(tsgluO)(2)(H2O)(6)] (2) and [Cd(bipy)(tsgluO)] (3) the crystal and molecular structure have been determined by X-ray diffraction (tsgluO=N-p-tolylsulfonyl-L-glutamate dianion, bipy=2,2'-bipyridine). In compound 1 the Zn-II ion exhibits a tetrahedral geometry arising from coordination of two carboxylic oxygens of two amino acid molecules and of two water molecules. In compound 2 each Cd-II ion of the dimeric unit is coordinated by oxygen atoms of tsgluO(2-) and water molecules in a distorted octahedral environment. In compound 3 the Cd-II ion is coordinated by 2,2'-bipyridine nitrogens and four oxygen atoms from three different tsgluO(2-) in a distorted octahedral geometry. (C) 1999 Elsevier Science Ltd. All rights reserved.

M. Borsari ; L. Menabue ; M. Saladini ( 1999 ) - Coordination properties of N-p-tolylsulfonyl-L-glutamic acid toward metal(II) - Part 2. Solution study on binary and ternary 2,2 '-bipyridine containing systems - POLYHEDRON - n. volume 18 - pp. da 1983 a 1989 ISSN: 0277-5387 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The binary and ternary systems 2,2'-bipyridine (bipy)-M-tsglu [M=Cu-II, Cd-II, Zn-II or Pb-II, tsglu=N-p-tolylsulfonyl-L-glutamic acid, hereafter abbreviated LH3] were investigated in aqueous solution by means of polarography, electronic spectroscopy and potentiometry, in order to identify the type, number and stability of complex species, as a function of pH and metal to ligand molar ratio. The prevailing species in the binary systems is the [ML](-) [M=Cu-II, Cd-II, (PI)-I-II] where the amino acid molecule is in the trianionic form and coordinates the metal ion through both the carboxylic groups and deprotonated sulfonamidic nitrogen. This coordination mode is also maintained in the ternary bipy containing systems. The addition of the aromatic base in the metal coordination, stabilizes the [M(bipy)L](-) species [M=Cu-II, Cd-II] with respect to the binary ones, while it enables the Zn-II ion to substitute for the sulfonamide nitrogen-bound hydrogen of tsglu. (C) 1999 Elsevier Science Ltd. All rights reserved.

D. Iacopino; L. Menabue; M. Saladini ( 1999 ) - Crystallographic study on metal(II) complexes with N-(2-nitrophenylsulfonyl)glycine - AUSTRALIAN JOURNAL OF CHEMISTRY - n. volume 52 - pp. da 741 a 748 ISSN: 0004-9425 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The interaction of M-II ions (M-II = Mn-II, Co-II, Ni-II, Cu-II, Zn-II, Cd-II, Pb-II) with N-(2-nitrophenylsulfonyl)glycine (NO(2)psglyH(2)) leads to the formation at acidic pH of the complex carboxylate-type M(NO(2)psgly-O)(2).xH(2)O species. At higher pH the deprotonation reaction of the sulfonamide nitrogen takes place, leading to the formation of the M(NO(2)psgly-N,O).xH(2)O species where the ligand acts as a chelating agent toward the metal ion through the carboxylic oxygen and the deprotonated sulfonamide nitrogen. In ternary systems the addition of 2,2'-bipyridine (bpy) allows the deprotonation of the sulfonamide nitrogen also in presence of metal ions such as Zn-II, Co-II and Ni-II, which were inactive in the binary system, and the solid compounds isolated are in the M/bpy/L molar ratio 1 : 1 : 1 (M-II = Cu-II, Zn-II) or 1 : 2 : 1 (M-II = Co-II, Ni-II, Cd-II). Here we describe the crystal and molecular structures of NO(2)psglyH(2) (1), [Pb(NO(2)psgly-N,O)](n) (2), [Cd(bpy)(2)(NO(2)psgly-N,O)].H2O (3) and [Cu(bpy)(NO(2)psgly-N,O)(H2O)] (4).

G. LUSVARDI; L.MENABUE; M.SALADINI ( 1999 ) - EFFECT OF TEMPERATURE ON THE CHEMICAL AND PHYSICAL PROPERTIES OF SYNTHETIC FLUOROAPATITE - Biomateriali 1999 - ENEA Roma ITA) - pp. da 97 a 101 ISBN: 9788882860769 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Fluroapatite synthetic powders used as bioceramic coatings onto metallic substrate:the coatings are obtained by plasma spray tecnique ant its high temperature could modify the chemistry of the coating. Thermal behaviour of fluoroapatite is studied by means of diffractometric, infrared study and thermal analysis.After thermal treatment its high crystallinity,chemical and physical properties are maintained.The thermal effect cause a loss of weight due principally to CaCO3 decomposition, present as minor phase in the untreated fluoroapatite

C. Leonelli; G. Lusvardi; L. Menabue ( 1999 ) - Microstructure at the interface solution/bioactive glass cerium and silver addition in bioactive phosphosilicate glasses - BRITISH CERAMIC PROCEEDINGS - n. volume 2 - pp. da 543 a 544 ISSN: 0268-4373 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Phosphosilicate glasses added with silver and cerium are studied in order to verify their bioactivity; the study is carried out in vitro and the results indicated that these glass are potentially bioglasses.

Menabue L; Saladini M; Bavoso A; Ostuni A ( 1998 ) - Investigation on coordination ability of N-chloro-acetylglycine towards Cu(II) in solid and solution state - INORGANICA CHIMICA ACTA - n. volume 268 - pp. da 205 a 210 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The solution and solid state behavior of the binary system Cu(II)-N-chloroacetylglycine (Cl-acglyH) and the corresponding ternary systems with 2,2´-bipyridine (bpy) and 1,10-phenanthroline (ophen) were investigated by means of pH-metric and spectrophotometric titrations. The X-ray crystal structure of the complex [Cu(ophen)(Cl-acgly)(2)]..2H2(O) (Cl-acgly=N-chloroacetylglycine monoanion) is also reported. The crystals of the compound C20Cl2CuN4O8H22 are monoclinic, space group P2(1)/c, a=17.574(3), b=7.125(2), c=25.113(6) Angstrom, beta=130.04(2)degrees, Z=4, R=0.077, R-w=0.088. The structure consists of monomeric [Cu(ophen)(Clgly)(2)] units and lattice water molecules. The Cu(II) atom is square planar coordinated by two carboxylic oxygens of two amino acid molecules and two nitrogen atoms of the ophen molecule. Two long contacts involve the uncoordinated carboxylic oxygens. Crystal packing is due to ring-stacking interaction involving ophen molecules and to a strong intramolecular hydrogen bond involving the chlorine atom and the amidic nitrogen of one ligand molecule. In solution the species [CuI2] and [CuALOH] (A = bpy or ophen) prevail in the binary and ternary system, respectively, both arising from carboxylic-oxygen-metal coordination of the amino acid molecule. The coordination of the OH- group in the ternary species prevents metal hydrolysis up to pH 11. The possibility of forming hydrogen bond interactions involving the chlorine atom seems the to be determinant factor in stabilizing the ternary complexes.

A. BAVOSO; A. OSTUNI; G. BATTISTUZZI; L. MENABUE; M. SALADINI; M. SOLA ( 1998 ) - Metal ion binding to a zinc finger peptide containing the Cys-X-2-Cys-X-4-His-X-4-Cys domain of a nucleic acid binding protein encoded by the Drosophila Fw-element - BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS - n. volume 242 - pp. da 385 a 389 ISSN: 0006-291X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The metal binding properties of a 18-residue zinc finger peptide containing a CCHC box which reproduces one of the cysteine-rich domains of a putative nucleic acid binding protein encoded by the Fw transposable element from Drosophila melanogaster were investigated through electronic and H-1 NMR spectroscopy. Dissociation constants of 2(+/-1)x10(-12) M and 4(+/-1)x10(-7) M were determined for the Zn2+ and Co2+ adduct, respectively. These values are similar to those for other CCHC-peptides investigated previously, although the length of the spacer between the second cysteine and the histidine apparently exerts some influence on the spectral properties and on the stability of the Co2+-peptide adduct. The 1H NMR spectrum of the present Co2+-derivative contains a number of well resolved hyperfine-shifted resonances between 350 and -50 ppm which arise from the metal binding residues and nearby groups. These peaks can in principle be profitably exploited to monitor protein-nucleic acid interactions.

L. MENABUE; M. SALADINI; N. UGOLETTI ( 1998 ) - Metal(II) binding by natural ionic glycosides: A solution study on 2,2 '-bipyridine containing ternary systems of Cu(II) and Ni(II) with lactobionic acid - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 69 - pp. da 217 a 222 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The stability constants of the complexes formed between CU2+ or Ni2+ and lactobionic acid in binary and ternary 2,2'-bipyridine containing systems, were determined by potentiometric pH titrations in aqueous solution (25 degrees C, I = 0.1M, NaNO3). The pH dependence of the electronic spectra of these systems is also reported. Lactobionic acid reacts as chelating agent towards metal ions via carboxylic and alpha-hydroxylic oxygens; the total amount of free ions at physiological pH is less than 10%, in both binary and ternary systems. The general tendency to form complexes less stable than those of Cu(II) persists in the case of Ni(II) complexes solid compounds were also isolated and characterized by FT-IR and UV-VIS spectroscopies. (C) 1998 Elsevier Science Inc. All rights reserved.

Battistuzzi G; Borsari M; Menabue L; Saladini M; Sola M ( 1998 ) - Palladium(II) complexes of N-sulfonyl-asparagine and glutamine. Evidence for metal coordination of the deprotonated amide nitrogen of the side-chain - INORGANICA CHIMICA ACTA - n. volume 273 - pp. da 397 a 402 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The binary and ternary (bpy) palladium(II) complexes of the N-sulfonyl derivatives of asparagine and glutamine were studied by polarography and electronic spectra as a function of pH and metal-to-ligand molar ratio. Binary [Pd(L-NO)] and [Pd(L-NO)(2)](2-) complexes are formed below pH 4, in which the N-sulfonyl-aminoacids act as bidentate N,O-chelate ligands through the deprotonated sulfonamide nitrogen and the carboxylate oxygen. No other binary species are detected at higher pH values. Both ligands form the ternary complex [Pd(L-NO)(bpy)] below pH 8.5. At higher pH values, the electrochemical and spectral data indicate that the ligands undergo an acid-base equilibrium with an apparent pK(a) value of about 10, which most probably corresponds to the deprotonation and metal coordination of the amide nitrogen of the side-chain. The overall stability constants for the binary and ternary complexes were determined polarographically and discussed in comparison with those for the homologous species formed by N-sulfonyl-aminoacids with a non-coordinating side-chain.

G. Lusvardi; L. Menabue; M. Saladini ( 1997 ) - Factors influencing the removal of Pb(II) ion by means of hydroxyapatite - ANNALI DI CHIMICA - n. volume 87 - pp. da 337 a 351 ISSN: 0003-4592 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction behaviour of synthetic hydroxyapatite, Ca-5(PO4)(3)OH (HAP) toward the Pb(II) ion is investigated for the Pb/Ca molar ratio range 1-0.01, at different temperature values, surface areas of HAP, pH values and solid/liquid ratio by means of ion concentration and pH measurements, powder diffractometry and I.R. spectroscopy. The Pb-containing solid phase is invariably Pb-5(PO4)(3)OH (PbAP) and in addition, at pH>6, the presence of 3PbO . H2O is also verified. The rate of the reaction depends mainly on pH, Pb/Ca molar ratio and HAP surface area and is due to PbAP precipitation alternated with to HAP dissolution. At a Pb/Ca molar ratio of 0.01 the adsorption Pb(ll) on the HAP surface should also occur. At Pb/Ca molar ratios in the range 1-0.6 the reaction is quantitative only at a high surface area. At Pb/Ca molar ratios in the range 0.2-0.01 the reaction is quantitative irrespective of the surface area. For the molar ratio Pb/Ca = 0.01 the EPA limit level of 0.015 mg/l is reached after 2 days by using HAP with a surface area of 57.80 m(2) g(-1).

G. Battistuzzi; M. Borsari; L. Menabue; M. Saladini; M. Sola ( 1996 ) - Amide group coordination to the Pb2+ ion - INORGANIC CHEMISTRY - n. volume 35 - pp. da 4239 a 4247 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The binary and ternary (2,2'-bipyridine) complexes of dipositive lead formed by N-carbonyl and N-sulfonyl amino acids, which are ligands containing the peptide and the sulfonamide group, respectively, were investigated in aqueous solution by NMR and differential pulse polarography, and some were also characterized crystallographically. N-Tosylglycine, N-tosyl-beta-alanine, and N-benzoylglycine behave as simple carboxylate ligands at acid pH, while around neutrality they switch to dianionic N,O-bidentate chelating ligands due to the involvement of the deprotonated amide nitrogen as an additional donor site. The same coordination behavior is maintained in the presence of 2,2'-bipyridine. The binary and ternary species formed in solution, and their stability constants were determined and compared with those of the homologous complexes of Pd2+, Cu2+, Cd2+, and Zn2+. The Pb2+ ion is the only dipositive metal which is effective in promoting peptide nitrogen deprotonation in benzoylglycine. The molecular structures of [Pb(N-tosylglycinato-N,O)(H2O)] (1), [Pb(N-benzoylglycinato-O)(2)-(H2O)(2)]. 2H(2)O (2), and [Pb(N-tosylglycinato-O)(2)(bpy)] (3) were determined by X-ray crystallography (O and N,O refer to the ligands binding as carboxylates and as N,O-chelating dianions, respectively). These compounds are all polymeric with six- to eight-coordinate metals showing distorted coordination geometries indicative of a stereochemically active metal lone pair. Polymerization is invariably determined by a bidentate chelate carboxylate group with one oxygen bridging between two metals, and in 2 and 3 it occurs through the formation of chains of Pb2O2 square-planar rings. The binding set in 1, involving a deprotonated amide nitrogen and a sulfonic oxygen, is unprecedented for the Pb2+ ion. This work provides new information on the solution and solid state chemistry of dipositive lead with ligands of biological interest, a research area that has received little attention in the past, although it is of great relevance for understanding the mechanisms of metal toxicity.

BORSARI M; MENABUE L.; SALADINI M ( 1996 ) - Amide nitrogen coordination of Co(II) and Ni(II) in ternary 2,2'-bipyridine-containing systems. A solution and solid state study. JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS; p. , ISSN: 0300-9246 - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume nessun volume - pp. da 4201 a 4205 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Cobalt(II) and Nickel(II) interactions towards N-protected aminoacid were investigated both in solution and solid state and the ternary compexes with 2,2'-bipyridine. The experimental conditions (pH, metal:ligand:amine ratio) for amide nitrogen deprotonation in ternary systems were defined and the stability constant of ternary complexes were evaluated. The crystal structure of Co(II)bis-tosylglycinato 2,2'-bipyridine complex was determined.

A. Bavoso; L. Menabue; M. Saladini; M. Sola ( 1996 ) - Coordination of 2-hydroxyhippuric acid to the copper(II) ion: A solution and solid state study - INORGANICA CHIMICA ACTA - n. volume 244 - pp. da 207 a 212 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The solution and solid state behaviour of the binary system Cu(II)-2-hydroxyhippuric acid (2-OHhipH) and the corresponding ternary system with 2,2'-bipyridine (bpy) were investigated through pH-metric titrations and X-ray crystallography. In solution the species [CuLH(-1)](-) and [CubpyL] were found to prevail in the binary and in the ternary system, respectively, both involving metal coordination of the phenolate oxygen. A spectrophotometric pK(a) of 5.2(2) was determined for the deprotonation of the phenolic hydroxy group in the ternary system The crystals of the complex [Cu(bpy)(2-OHhip)](2) . 8H(2)O were found suitable for X-ray structure determination. The crystals of the compoundC(19)H(23)CuN(3)O(8) are monoclinic, space group P2(1)/c,a=7.717(2),b=11.502(2),c=23.275(4) Angstrom,beta=94.86(3)degrees,Z=4,R=0.033,R(w)=0.035. The structure consists of dimeric [Cu(bpy)(2-OHhip)](2) it units and lattice water molecules. The Cu(II) atom is pentacoordinated by the two nitrogen atoms of the bpy molecule and the carbonyl and phenolate oxygen atoms of the ligand in the equatorial plane, and by a bridged phenolate oxygen in the apical position, giving rise to a distorted square pyramidal geometry. The binding mode of 2-OHhipH is discussed by reference to related ligands.

G. LUSVARDI; L. MENABUE; M. SALADINI ( 1995 ) - Cadmium(II) N-(p-toluenesulphonyl)-L-glutaminate - ACTA CRYSTALLOGRAPHICA. SECTION C, CRYSTAL STRUCTURE COMMUNICATIONS - n. volume C51 - pp. da 2287 a 2289 ISSN: 0108-2701 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Crystals of [Cd(C12H15N2O5S)(2)] contain dimensional polymeric network in which Cd2+ ions are octahedrally coordinated by O atoms.

G. Lusvardi; L. Menabue; M. Saladini ( 1995 ) - Coordination properties of sulfonyl-N-aminoacids: Crystal and molecular structure of the [Zn(II)(N-(p-toluenesulfonyl)-L-glutaminate)(2)(H2O)(2)] complex - JOURNAL OF CHEMICAL CRYSTALLOGRAPHY - n. volume 25(11) - pp. da 713 a 716 ISSN: 1074-1542 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The coordination behavior of N-tosyl-L-glutamine (hereafter abbreviated as tsglnH, tosyl = toluenesulfonyl group) toward the Zn(II) ion is investigated by means of structural and spectroscopic techniques. From aqueous solution, at acidic pH the Zn(II) ion separates a compound of empirical formula Zn(tsgln)(2) . 2H(2)O whose crystal structure is determined. The crystal is monoclinic, space group C2, with cell dimensions: a = 19.775(5), b = 5.3146(3), c = 16.543(8)Angstrom, beta = 119.93(3)degrees, Z = 2. The Zn(II) is tetrahedrally coordinated by two symmetry-related tsgln monoanions acting as monodentate carboxylate Ligands and two symmetry related water molecules. The Zn-O bond distances are similar while the angles at Zn(II) ion differ significantly from those of regular tetrahedron. The side chain amide group does not participate in metal coordination and forms intermolecular hydrogen bonds.

Brückner, S.; Lusvardi, G.; Menabue, L.; Saladini, M. ( 1995 ) - Crystal structure of lead hydroxyapatite from powder X-ray diffraction data - INORGANICA CHIMICA ACTA - n. volume 236 - pp. da 209 a 212 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal structure of lead hydroxyapatite, Pb-10(PO4)(6)(OH)(2), is refined on powder XRD data using the Rietveld method. The unit cell is hexagonal, a=b=9.866(3) and c=7.426(2) Angstrom, space group P6(3)/m, Z=1 (relative to the specified formula). Results are discussed and compared with previous structures of hydroxyapatite and partially lead-substituted hydroxyapatites. Now that the entire range of lead substitution is covered, it is possible to detect a coherent trend in the distortions of the crystal packing introduced by the different ability of the two metallic crystal sites to accommodate Pb ions.

G. LUSVARDI; L. MENABUE; M. SALADINI; M. SPAGGIARI ( 1995 ) - Effect of pH and anions on hydroxyapatite-Cu2+ solid-liquid interactions - JOURNAL OF MATERIALS CHEMISTRY - n. volume 5(3) - pp. da 493 a 497 ISSN: 0959-9428 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction of synthetic Ca-5(PO4)(3)OH (HAP) with CU2+ ions is investigated by means of pH, pCu and pCa measurements as a function of the time, pH and electrolyte type (NaCl, NaHCO3, Na2HPO4). The solid phases separated after different reaction times are investigated with X-ray diffraction (XRD) and IR techniques. The Cu2+ does not form mixed compounds with Ca2+ and does not replace Ca2+ in the HAP structure. The presence, in an appropriate concentration, of anions which form very insoluble Cu2+ compounds favours the precipitation of the latter with no involvement of HAP. If the concentration of the anions is low, the precipitation of Cu2+ also involves HAP and this behaviour is particularly enhanced with Na2HPO4.

LUSVARDI G.; L. MENABUE; SALADINI M. ( 1995 ) - Reaction behaviour of hydroxyapatite toward the Zn2+ ion. - Advances in Sciences and Technology - TECHNA GROUP FAENZA ITA) - n. volume 12 - pp. da 35 a 42 ISBN: 9788886538114 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

The reaction of synthetic hydroxyapatite, Ca5(PO4)3OH (HAP), with Zn2+ ions is investigated by means of pH, pZn, pCa and pNa measurements as a function of the time, temp. (40 and 60) and salts compn. and at different Zn2+/Ca2+ molar ratios in the range 1 - 0.1. The solid phases sepd. after different times of reaction were investigated with XRD and IR techniques. The Zn2+ ions added to HAP give rise to a soln. with pH >6 which inhibits any reaction involving HAP. No effect is obsd. by addn. of NaCl. At pH <5 Zn2+ forms Zn3(PO4)2.2H2O and does not replace Ca2+ in HAP structure. The addn. of an excess of NaHCO3 or a mixt. of NaHCO3 and Na2HPO4, with a molar ratio NaHCO3/Na2HPO4 = 30 gives rise to the formation ZnCO3 (smithsonite).

L. MENABUE; SALADINI M ( 1994 ) - Catena-Poly[zinc(II)-bis{μ -(N-carbamoylglycinato)}-O:O'';O'':O], [Zn(C3H5N2O3)2]. - ACTA CRYSTALLOGRAPHICA. SECTION C, CRYSTAL STRUCTURE COMMUNICATIONS - n. volume C50 - pp. da 887 a 889 ISSN: 0108-2701 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The structure of [Zn(hyda)2] (hydaH = N-carbamoylglycine or hydantoic acid) consists of polymeric linear chains in which pairs of Zn(II) ions are connected by pairs of hydantoate anions coordinated through their carboxylic and amidic O atoms. The coordination around the metal atom is tetrahedral.

CORRADI A BONAMARTINI; GOZZOLI E; L. MENABUE; SALADINI M; BATTAGLIA L P; SGARABOTTO P ( 1994 ) - Palladium(II) complexes of N-sulfonylamino acids. Part 1. Solid-state behavior of binary and ternary 2,2'-bipyridine-containing systems. - Royal Society of Chemistry:Thomas Graham House, Science Park, Cambridge CB4 0WF United Kingdom:011 44 1223 432360, EMAIL: sales@rsc.org, INTERNET: http://www.rsc.org, http://www.chensoc.org, Fax: 011 44 1223 423429 ) - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume 1994 - pp. da 273 a 278 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal and molecular structure of ternary Pd(II) complexes with N-sulfonylaminoacids and of their derivative with 2,2'-bipyridine has been reported. The coordination geometry around Pd(II) ions is always square-planar and the aminoacid dianions act as bidentate through a carboxylate oxygen and the deprotonated sulfonamide nitrogen.

BATTISTUZZI G; GAVIOLI G; BORSARI M; MENABUE L; SALADINI M; SOLA M ( 1994 ) - PALLADIUM(II) COMPLEXES OF N-SULFONYLAMINO ACIDS .2. COORDINATION BEHAVIOR UNDER STRONGLY ACIDIC CONDITIONS - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume 1994 - pp. da 279 a 283 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The ligation of a series of N-sulfonylamino acids (H(2)L) to Pd2+ was investigated by means of d.c. polarography, H-1 NMR and electronic spectroscopy. The first amino acid is found to bind to the metal under extremely acidic conditions, with an apparent pK(NH) value of about 1, while an additional molecule binds with a pK(NH) ranging from 3.1 to 3.7 for the different amino acids. These nitrogen-deprotonated complexes appear not to involve carboxylate complexes as stable precursors. Proton NMR spectroscopy indicates the presence of geometric isomers for the [PdL(2)](2-) species.

BATTISTUZZI G; GOZZOLI E; BORSARI M; MENABUE L; SALADINI M; SOLA M ( 1994 ) - PALLADIUM(II) COMPLEXES OF N-SULFONYLAMINO ACIDS .3. TERNARY ADDUCTS WITH 2,2'-BIPYRIDINE - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume 1994 - pp. da 285 a 287 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The equilibria involved in the formation of ternary adducts of Pd2+ with N-sulfonylamino acids (H,L) and 2,2'-bipyridine were investigated through d.c. polarography, H-1 NMR and electronic spectroscopy in aqueous solution starting from strongly acidic conditions. The formation of the ternary species appears to proceed through the initial binding of the heteroaromatic base to Pd2+ followed. at higher pH values. by ligation of one amino acid dianion. The pK(NH) value of the latter. ranging from 3.2 to 4.7 for the different amino acids, is unchanged or slightly higher compared to that observed in the formation of the [PdL(2)](2-) species from the precursor [PdL] in the binary Pd2+-L(2-) systems. A comparison is made with the corresponding ternary complexes of Cu2+, Cd2+ and Zn2+.

M. Sola; M. Borsari; J. A. Cowan; L. Menabue; M. Saladini; R. Battistuzzi ( 1994 ) - Redox equilibria in metalloproteins and characterization of model complexes - Advances in Free Radicals in disease - CLEUP EDITRICE PADOVA Padova ITA) - n. volume 3 - pp. da 167 a 175 ISBN: 887178264X ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

Electrochemical and NMR studies of the copper center in superoxide dismutase are described.

L. MENABUE; SALADINI M; SANTI P ( 1994 ) - STRUCTURAL, SPECTROSCOPIC AND POTENTIOMETRIC INVESTIGATION ON THE COORDINATION PROPERTIES OF 4-NO2-HIPPURIC ACID TOWARDS CU(II) IN BINARY AND TERNARY-SYSTEMS - INORGANICA CHIMICA ACTA - n. volume 227 - pp. da 105 a 112 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The solid state and aqueous solution study on the binary and ternary system copper(II)-4-NO2-hippuric acid is reported. The binary complex separated in the solid state is [Cu(4-NO2-hip)(2)(H2O)(2)](2).4H(2)O and the crystal structure has been determined. The compound is monoclinic, space group P2(1)/a, with cell dimensions a=7.289(3), b=44.25(1), c=7.344(7) Angstrom, beta=102.05(6)degrees, Z=2, R=0.055 and R'=0.053. The structure consists of dimeric penta-coordinated [Cu(4-NO2-hip)(2)(H2O)(2)](2) units and lattice water molecules. The copper atom is coordinated by two (4)-NO2-hip anions acting as carboxylate ligands and two water molecules. One (4)-NO2-hip anion acts as monodentate ligand and the second acts as monodentate bridging ligand through one carboxylic oxygen which is an equatorial ligand for one copper atom and is the apical ligand for the second copper atom. In the ternary system with 2,2'-bipyridine (bpy) we separated mono-amine and bis-amine species, in that with 1,10-phenanthroline (ophen) only the mono-amine species was obtained. For the compound [Cu(bpy)(2)(4-NO2-hip)].NO3.H2O the crystal and molecular structure was determined. The crystal is triclinic, space group P1, with cell dimensions: a=10.162(2), b=10.953(5), c=13.651(2) Angstrom, alpha=96.76(3), beta=100.40(1), gamma=96.19(3)degrees Z=2, R=0.043 and R'=0.048. The copper atom is coordinated by the two bpy molecules and by the 4-NO2-hip anion which acts as an asymmetrically bidentate ligand through the carboxyl group. The Cu-O(1) bond distance is normal, while the Cu-O(2) one is significantly longer (2.646(3) Angstrom), so the geometry can be represented as (4+1+1*). On the basis of the ESR spectrum the copper(II) ground state is established as d(x2-y2). In solution the prevailing species are [CuL2(]) in the binary system, [CuAL(OH) and [CuAL(OH)] in the ternary system.

G. LUSVARDI; L. MENABUE; M. SALADINI ( 1994 ) - Substituent effect on the coordination ability of the amide group of N-protected amino acids - INORGANICA CHIMICA ACTA - n. volume 218 - pp. da 53 a 58 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The binary system Cu(II)-hydantoic acid (hydaH) and the corresponding ternary systems with 2,2'-bipyridine(bpy) and 1,10-phenanthroline (ophen) were investigated both in the solid state and solution. The crystal and molecular structure of the complex [Cu(ophen)(hyda)2].H2O was also determined. The crystal of the compound C18H20CuN6O7 is monoclinic, space group P2(1)/c, a = 7.601(5), b = 14.647(2), c = 19.714(3) angstrom, beta = 96.57(3), Z = 4, R = 0.049, R(w) = 0.053. The structure consists of discrete [Cu(ophen)(hyda)2] units and lattice water molecules. The Cu(II) atom is coordinated in the equatorial plane by two nitrogens from the ophen molecule and two oxygens from two hydantoate anions; the nitrogen atom of the neutral NH group of a hydantoate anion occupies the more distant fifth position (Cu-N(l) = 2.541(5) angstrom) giving rise to elongated square-pyramidal geometry. In solution the carboxylate species [CuL2] is formed in the binary system and the species [CuAL2], [CuAL(OH)] in the ternary systems with bpy and ophen. Spectroscopic data indicate that any possibility of the NH group being coordinated in solution can be excluded.

S. BRUCKNER; L. MENABUE; M. SALADINI; M. TOLAZZI ( 1993 ) - Coordination behavior of Ar-SO2-N-amino acids toward the Mn(II) ion. Crystal and molecular structure of [Mn(tsgln)2] and [Mn(ts-a-ala)2(H2O)]2.78H2O0.92CH3OH - INORGANICA CHIMICA ACTA - n. volume 214 - pp. da 185 a 191 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A series of complexes of Ar-SO2-N-amino acids (Ar-SO2-= 4-toluensulfonyl- (hereafter abbreviated as tosyl) (ts), benzenesulfonyl (bs); amino acid=glycine (gly), DL-alpha- and beta-alanine (alpha- and beta-ala), asparagine (asn) and glutamine (gln)) with Mn(II) was synthesized and characterized by means of spectroscopic and thermal analyses. For two of them [Mn(ts-alpha-ala)2(H2O)].2.78H2O.0.92CH3OH (1) and [Mn(tsgln)2] (II) the crystal and molecular structure was also determined. I crystallizes in the orthorhombic Pbcn space group, with cell dimensions: a = 31.212(3), b = 11.248(2), c = 9.051(2) angstrom, Z = 4. II crystallizes in the monoclinic C2 space group, with cell dimensions: a = 17.490(3), b = 5.259(2), c = 17.432(2) angstrom, beta = 120.70(4)-degrees, Z = 2. In both compounds the Mn(II) atom is octahedrally coordinated by six oxygen atoms. In I the amino acid monoanion bridges two Mn atoms through the carboxyl group giving rise to a 1D polymer, the coordination to Mn is completed by two water molecules in a special position. In II each amino acid monoanion bridges two Mn atoms through the carboxyl group and binds a third Mn atom through the carbonyl oxygen of the terminal amide group, giving rise to a 2D polymer.

MENABUE L; SALADINI M ( 1993 ) - COORDINATION BEHAVIOR OF SULFA-DRUGS - SYNTHESIS, STRUCTURAL, AND SPECTROSCOPIC INVESTIGATION ON M(II) (N(1)-PYRIMIDIN-2YL-SULFANILAMIDO)2. X H2O - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 49 - pp. da 201 a 207 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Co(II), Ni(II), Zn(II), and Cd(II) complexes of sulfadiazine (HSD) were prepared and characterized by spectroscopic data. For [Cd(SD)2].2H2O the crystal and molecular structure is reported. The compound crystallizes in the monoclinic C2/c space group with Z = 4, in a cell of dimensions a = 1.9.879(3), b = 8.730(3), c = 16.538(3) angstrom, beta = 122.15(2)degrees. Least-squares refinement of 2019 reflections [I greater-than-or-equal-to 2sigma(I)] gave a final R = 0.034. The structure consists of a monodimensional polymeric chain running along the b axis in which the cadmium atom is coordinated to two sulfonamido and two amino nitrogens from four symmetry-related SD anions. The coordination geometry around the metal is distorted tetrahedral. Hydrogen bonds involving the water molecule contribute to crystal stability.

S. BRUCKNER; G. LUSVARDI; L. MENABUE; M. SALADINI ( 1993 ) - Effect of Cu2+ Ion on the Structural Stability of Synthetic Hydroxyapatite - JOURNAL OF MATERIALS CHEMISTRY - n. volume 3(7) - pp. da 715 a 719 ISSN: 0959-9428 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction of synthetic hydroxyapatite, Ca5(PO4)3OH (HAP), with Cu2+ ions is investigated by means of pH, pCu and pCa measurements as a function of the time and temperature (30, 40, 45 and 60-degrees-C) and at different CU2+:Ca2+ molar ratios in the range 0.01-1.07. The solid phases separated after different times of reaction were investigated with XRD and IR techniques. The Cu2+ ions give rise to an acidic solution and promote HAP dissolution; HAP does not incorporate the Cu2+ ions and a new phase corresponding to the mineral Cu2(PO4)OH (Libethenite) crystallizes quantitatively. In the course of the reaction, with the ratio Cu2+:Ca2+ in the range 0.1-1, the pH decreases owing to the release of phosphoric acid, whereas it increases for the ratio 0.01. At physiological ionic strength, obtained with NaCl, the solid phase containing Cu is again libethenite, but the process is notably accelerated.

CORRADI AB; BRUCKNER S; CRAMAROSSA MR; MANFREDINI T; MENABUE L; SALADINI M; SACCANI A; SANDROLINI F; GIUSTI J ( 1993 ) - SYNTHESIS AND CHARACTERIZATION OF ONE-DIMENSIONAL POLYMERIC CHLOROCADMATE(II) SYSTEMS - CHEMISTRY OF MATERIALS - n. volume 5 - pp. da 90 a 97 ISSN: 0897-4756 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this paper we report the synthesis and the structural, thermal, electrical properties of 1-D polymeric chlorocadmates(II), having N-methylpropane-1,3-diammonium (mepnH2) and NN-diethylpropane-1,3-diammonium (et2pnH-2) as countercations. The (mepnH2)2[Cd3CI10] crystallizes in space group P2(1)/c. The unit cell dimensions are a = 10.164 (3) angstrom, b = 13.434 (10) angstrom, c = 10.099 (3) angstrom, beta = 112.04 (3)-degrees, V = 1278 (i) angstrom3, z = 2. The final R value for 2124 reflections (I > 2sigma(I)) is 0.0445 (R(w) = 0.0384). Its structure consists of N-methylpropane-1,3-diamine dications and infinite chains of [(Cd3Cl10)n4n-]n moieties forming 1-D polymer running along the x axis. The (et2pnH2)2[Cd5Cl14].2H2O crystallizes in space group P1BAR. The unit cell dimensions are a = 6.874 (1) angstrom, b = 10.381 (1) angstrom, c = 14.572 (i) angstrom, a = 100.14 (1)-degrees, beta = 99.31 (1)-degrees, gamma = 97.46 (1)-degrees, V = 996.7 (2) angstrom3, Z = 1. The final R value for 3405 reflections (I > 2sigma(I)) is 0.0452 (R(w) = 0.0393). Its structure consists of N,N-diethylpropane-1,3-diamine dications, infinite alternate stacked pseudoplanar trinuclear [Cd3Cl8]2- and dinuclear [Cd2Cl6]2- dianions and uncoordinated water molecules. Both the packings are strengthened by N-H ... Cl hydrogen bonds between anions and cations. A first-order phase transition of (mepnH2)2[Cd3CI10] has been identified by DSC measurements and X-ray powder diffraction, related to the disordering of the hydrocarbon chains at high temperature. This increases the cell volume. The electrical conductivity of the compounds can be envisaged as protonic, and the whole electrical behavior can be correlated to their structures and phase transition.

L. Menabue; L. Forti; G. C. Pellacani; M. Fabbri; A. Krajewski; A. Ravaglioli ; G. Giunchi ( 1992 ) - A Study of Materials Suitable to Produce Bioceramics with Controlled Porosity for Prosthetic Implants Stabilized by Bone Tissue Ingrowth - BIOMATERIALI - n. volume 6 - pp. da 107 a 112 ISSN: 1124-3554 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Porous bioceramic pieces obtained by various methods were studied and here reported. The materials taken into consideration are alumina and particularly hydroxyapatite. Among the various materials that allow the formation of large pores (pore makers) with high porosity percentage, the following showedto be the most suitable: polyurethane, naphtalene and strontium carbonate. The obtained pores are communicating and their average diameter is significally high to succeed in hosting cells and blood microvessels inside.

BONAMARTINI CORRADI A.; BATTAGLIA L.P.; MENABUE L; SALADINI M.; SOLA M. ( 1992 ) - Deprotonated amide nitrogen coordination to the cadmium(II) ion in ternary 2,2'-bipyridine complexes with n-sulfonyl amino acids. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume - - pp. da 2623 a 2628 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A solid-state investigation of cadmium(II) and zinc(II) ternary 2,2′-bipyridine (bipy), complexes of N-(benzenesulfonyl)glycine (bsgly) and N-(toluene-p-sulfonyl)glycine (tsgly) is presented. The crystal structure of [{Cd(bipy)(tsglyO)2}2]1, separated from preparations at pH 7, and of [{Cd(bipy)(bsglyNO)}4]·8H2O 2 separated at pH 11 are described. Complex 1 crystallizes in the triclinic space group P, Z= 2, a= 10.474(10), b= 15.902(3), c= 18.202(9)Å, α= 98.49(2), β= 91.17(5) and γ= 98.31(3)°. The structure consists of dimeric units in which the cadmium atoms are bridged by two carboxylic oxygens. Metal co-ordination is via the two nitrogens of a bipy molecule and four carboxylate oxygens from the amino acid monoanion. A long Cd O contact completes seven co-ordination. The final R index was 0.0509. Complex 2 crystallizes in the monoclinic space group P21/c, Z= 4, a= 12.525(5), b= 15.251(4), c= 21.717(3)Å and β= 92.36(3)°. The structure is built up of tetrameric units in which the cadmium atoms are joined by monoatomic bridging carboxylic oxygens. Each cadmium is six-co-ordinated through bipy nitrogens and sulfonamide nitrogen and carboxylate oxygen of the amino acid molecules. The final R index was 0.0398. Infrared data for the homologous zinc(II) complexes, very similar to those of the above derivatives, indicate that zinc is also able to promote sulfonamide nitrogen deprotonation in these amino acid ligands in the solid state.

MASCIOCCHI N; MORET M; SIRONI A; BRUNI S; CARIATI F; POZZI A; MANFREDINI T; MENABUE L; PELLACANI GC ( 1992 ) - STRUCTURAL AND SPECTROSCOPIC CORRELATIONS IN CADMIUM(II) HALIDE-COMPLEXES OF 2,2-DIMETHYLPROPANE-1,3-DIAMINE - INORGANIC CHEMISTRY - n. volume 31 - pp. da 1401 a 1406 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Compounds of formula Cd(dmpd)2X2 (dmpd = 2,2-dimethylpropane-1,3-diamine; X = Cl, Br, I) were prepared and investigated by means of structural and spectroscopic (IR and Raman) measurements. The Cd(dmpd)2I2 compound crystallizes in the monoclinic P2(1)/c space group, with two formula units in a cell of dimensions a = 6.235 (5) angstrom, b = 18.462 (9) angstrom, c = 8.294 (5) angstrom, and beta = 93.37 (6)-degrees, with R = 0.039 and R(w) = 0.044. The structure consist of discrete [Cd(dmpd)2I2] monomeric units, where the Cd atom is surrounded by four nitrogen atoms of two in-plane chelating dmpd molecules and by two iodine atoms asymmetrically coordinated axial positions. The Cd(dmpd)2Br2 compound crystallizes in the triclinic P1BAR space group, with Z = 3 and a cell of dimensions a = 12.713 (2) angstrom, b = 16.592 (2) angstrom, c = 6.281 (3) angstrom, alpha = 91.22 (2)-degrees, beta = 96.67 (2)-degrees, and gamma = 78.72 (3)-degrees, with R = 0.031 and R(w) = 0.036. The structure consists of 1:1 molecular packing of Cd(dmpd)2Br2 monomeric and [Cd(dmpd)2Br2]2 dimeric units. In the monomer the Cd atom is octahedrally coordinated by four in-plane nitrogen atoms of two chelating dmpd molecules and by two bromine atoms in axial positions. The dimer consists of a pair of octahedrally coordinated Cd atoms, related by an inversion center, connected in a 12-membered metallacycle by two ambidentate dmpd molecules. The octahedral arrangement each Cd atom in the dimer is completed by an in-plane chelating dmpd and by two bromine atoms, axially coordinated. The Cd(dmpd)2Cl2 compound is isomorphous with the bromide derivative, with unit cell dimensions a = 12.714 (3) angstrom, b = 16.228 (3) angstrom, c = 6.087 (5) angstrom, alpha = 91.61 (3)-degrees, beta = 96.02 (3)-degrees, and gamma = 77.76 (4)-degrees. The CdN stretching vibrations are discussed and assigned in the light of the known structures.

MENABUE L; SALADINI M ( 1992 ) - TRANSITION METAL(II) COMPLEXES OF A BIOLOGICAL BUFFER - STRUCTURAL AND SPECTROSCOPIC STUDY ON CO(II), NI(II), CU(II), ZN(II), AND CD(II) COMPLEXES OF N-[2-HYDROXY-1,1-BIS-(HYDROXYMETHYL)ETHYL]GLYCINE - JOURNAL OF CRYSTALLOGRAPHIC AND SPECTROSCOPIC RESEARCH - n. volume 22 - pp. da 713 a 719 ISSN: 0277-8068 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The structural and spectroscopic properties of complexes of N-[2-hydroxy-1,1-bis-(hydroxymethyl)ethyl]glycine (thmmg) with Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) were investigated. The complex [Zn(thmmg)2] crystallizes in the space group P2(1)/n, with a = 8.796(2), b = 9.050(3), c = 9.926(2) angstrom, beta = 97.35(1)-degrees and Z = 2; the copper(II) homolog is isomorphous. The complex [Ni(thmmg)2].6H2O Crystallizes in the space group P2(1)/n with a = 8.432(8), b = 8.495(2), c = 15.967(1) angstrom , beta = 95.57(2)-degrees and Z = 2; the cobalt(II) homolog is isomorphous. Ni(II) and Zn(II) complexes show an elongated octahedral coordination arising from two symmetry related amino acid molecules acting as a tridentate chelate through the amino nitrogen, one carboxylate oxygen, and one hydroxyl oxygen; the water molecules in the Ni(II) complex are not involved in metal coordination. The same ligand bonding mode may be suggested also for the Cu(II) and Co(II) complexes, while for Cd(II) only the nitrogen atom and the carboxylate oxygens seem to be involved in metal coordination.

GB GAVIOLI; M. BORSARI; L. MENABUE; M. SALADINI; M. SOLA ( 1991 ) - Cd2+ and Zn2+ interactions with amino acids N-substituted by a sulfonic group.Effect of the additional ligand 2,2'-bipyridine on the metal-induced amine deprotonation - INORGANIC CHEMISTRY - n. volume 30 - pp. da 498 a 502 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The interaction of N-(phenylsulfonyl)glycine and N-(tolylsulfonyl)glycine (L) with Cd2+ and Zn2+ was investigated through dc polarography, pH-metric titrations, and H-1 NMR spectroscopy. 2,2'-Bipyridine as additional ligand lowers the pK(a) of Cd2+-promoted deprotonation of the sulfonamide nitrogen (from 8 in the binary system to 7.6 in the presence of the heteroaromatic base), as previously observed for the Cu2+ ion, and, most of all, enables the Zn2+ ion to substitute for the sulfonamide nitrogen bound hydrogen of these ligands. It is known that Zn2+ is ineffective in such a substitution in binary Zn2+-L systems.

L. Forti; L. Menabue; M. Saladini ( 1991 ) - Coordination behavior of N-protected amino acids. Structural and spectroscopic study of complexes of CoII, NiII and CuII with N-(4-aminobenzoyl)glicine - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume 1991 - pp. da 2955 a 2959 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The structural and spectroscopic properties of complexes of N-(4-aminobenzoyl)glycine (HL) with Co(II), Ni(II) and Cu(II) have been investigated. The complex [{CoL2(H2O)2}n].2nH2O crystallizes in the space group P1BAR, with a = 8.027(2), b = 8.031(2), c = 10.033(1) angstrom, alpha = 96.52(2)degrees, beta = 100.17(2)degrees, gamma = 119.19(2)degrees and Z = 1; the nickel(II) homologue is isomorphous. The complex [(CuL2)n].4nH2O crystallizes in the space group P2(1)/n, with a = 4.673(1), b = 20.476(1), c = 12.026(1) angstrom, beta = 97.38(2)degrees and Z = 2. The cobalt(II) co-ordination geometry is tetragonally distorted octahedral with four oxygens from two water molecules and two carboxylate groups in the basal plane and two amino nitrogens in the apical position. The copper(II) complex shows a strongly distorted tetragonal-octahedral geometry with two oxygens and two amino nitrogens of different amino acidate anions in the basal plane and two oxygens in the off-z-axis position. The ligand acts as bidentate bridging giving rise to a polymeric one-dimensional chain in the cobalt(II) complex and two-dimensional layers in the copper(II) one.

G. Ciani; N. Masciocchi; A. Sironi; S. Bruni; F. Cariati; A. Pozzi; L. Forti; T. Manfredini; L. Menabue ( 1991 ) - Coordinative capability of propane-1,3-diamine: spectroscopic and structural properties of a complex of formula [Cd(pnH)4Cl2]Cl4 - INORGANICA CHIMICA ACTA - n. volume 189 - pp. da 13 a 18 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The compound [Cd(pnH)4Cl2]Cl4 (pn = propane-1,3-diamine) has been prepared and studied by means of spectroscopic (IR and Raman) and structural investigations. It crystallizes in the tetragonal P4nc space group (No. 104), with two formula units in a cell of dimensions: a = b = 11.972(4), c = 9.129(4) angstrom. The structure consists of an ionic packing of chlorine anions and of discrete [Cd(pnH)4Cl2]4+ cations; the Cd atoms are octahedrally coordinated to four nitrogen atoms of four distinct monoprotonated diamines and to two chlorine atoms in trans position to each other, showing very loose Cd-Cl bonding interactions (2.680(3) and 2.884(2) angstrom). The protonated ends of the propane-1,3-diamines interact with the non-coordinated chlorine ions via hydrogen bonding. The Cd-N and Cd-X stretching vibrations are discussed and assigned in the light of the known structures.

GAVIOLI GB; BORSARI M; MENABUE L; SALADINI M; SOLA M ( 1991 ) - COPPER(II) COMPLEXES WITH N-SULFONYL AMINO-ACIDS - STRUCTURE-STABILITY RELATIONSHIPS IN BINARY SPECIES AND TERNARY COMPLEXES WITH 2,2'-BIPYRIDINE - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume . - pp. da 2961 a 2965 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The stability of a series of binary and ternary 2,2'-bipyridine(bipy) complexes of Cu2+ with amino acids N-substituted by an arene sulphonic group has been analysed in 0.1 mol dm-3 NaClO4 or NaNO3 at 25-degrees-C. The stability constants determined by d.c. polarography are sensitive to the nature of the amino acid and of the aromatic moiety of the protecting group. The known lowering effect of bipy on the pK for metal-promoted sulphonamide nitrogen deprotonation in the ternary complexes is found to be quantitatively independent of the above structural features. The X-ray structure of the ternary species [Cu(bipy)(Bs-GlyNO)(H2O)] [Bs-GlyNO = N-benzenesulphonylglycinate(2-)] is also presented. The crystals are monoclinic, space group P2(1)/c, with a = 8.494(5), = 19.950(4), c = 11.295(7) angstrom, beta = 110.79(4)-degrees, Z = 4, and R = 0.036. The structure consists of [Cu(bipy)(Bs-GlyNO)(H2O)] units in which the Cu atom exhibits a tetrahedrally distorted square-pyramidal N3O2 coordination.

MENABUE L; SALADINI M ( 1991 ) - N-(ARYLSULFONYL)GLYCINES AS CYCLOMETALATING LIGANDS - CRYSTAL AND MOLECULAR-STRUCTURES OF DISODIUM BIS(MU-CHLORO)BIS[MU-N-(PHENYLSULFONYL)GLYCINATO-O,N,C]-BIS[MU-N-(PHENYLSULFONYL)GLYCINATO-O,O']TETRAPALLADATE(II) HEXAHYDRATE AND DISODIUM BIS(MU-CHLORO)BI - INORGANIC CHEMISTRY - n. volume 30 - pp. da 1651 a 1655 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The interaction of N-(phenylsulfonyl)- and N-(4-tolylsulfonyl)- (N-tosyl hereafter) glycine (Bsgly and Tsgly, respectively) with Pd(II) ion at pH congruent-to 3.5 gives rise to cyclometalation reactions leading to complexes of the formulas Na2[Pd4Cl2(Bsgly-O,N,C)2(Bsgly-O,O')2].6H2O (I) and Na2[Pd4Cl2(Tsgly-O,N,C)(Tsgly-O,O')]2.4.5H2O.2TsglyH (II) (Bsgly-O,N,C and Tsgly-O,N,C = O,N,C-bonded ligand; Bsgly-O,O' and Tsgly-O,O' = carboxylate bridging ligand; TsglyH = neutral N-tosylglycine). The complexes crystallize in the triclinic P1BAR space group with a = 13.469 (4) angstrom, b = 13.636 (4) angstrom, c = 15.005 (5) angstrom, alpha = 70.94 (2)-degrees, beta = 66.32 (2)-degrees, gamma = 88.59 (2)-degrees, and Z = 2 for I and a = 17.058 (1) angstrom, 18.897 (2) angstrom, c = 13.194 (1) angstrom, alpha = 94.61 (1)-degrees, beta = 107.98 (1)-degrees, gamma = 74.32 (1)-degrees, and Z = 2 for II. Both structures consist of two tetrameric units, symmetry generated from two independent [Pd2Cl(L-O,N,C)(L-O,O')] (L = Bsgly or Tsgly) monoanions. In each tetramer one Pd(II) atom is coordinated with the deprotonated sulfonamide nitrogen and the carbon atom of the aromatic ring in the ortho position to the sulfonyl group of a ligand molecule, the bridging chlorine atom, and one oxygen atom of a bridging carboxyl from a second ligand molecule. The other crystallographically independent Pd(II) atom is coordinated with the other oxygen of the bridging carboxyl, the chlorine atom, the deprotonated sulfonamide nitrogen, and the oxygen atom of a monodentate carboxylate group forming a N,O-chelate glycine-like ring. Both of the Pd(II) atoms show a slightly distorted square-planar coordination geometry. Infrared and NMR results are also reported.

L. P. Battaglia; A. Bonamartini Corradi; G. Pelosi; L. Menabue; M. Saladini; Sola M.; G. Marcotrigiano; P. Morini ( 1991 ) - Structural and Spectroscopic Properties of N-Benzenesulphonylglycine Complexes with Copper(II). - JOURNAL OF CRYSTALLOGRAPHIC AND SPECTROSCOPIC RESEARCH - n. volume 21 - pp. da 313 a 319 ISSN: 0277-8068 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The structural and spectroscopic properties of (N-benzenesulphonylglycinato)triaquacopper(II) (complex I) and dipotassium bis (N-benzenesulphonylglycinato) cuprate(II) (complex II) have been determined.

L. MENABUE; M. SALADINI; M. SOLA ( 1990 ) - Deprotonated amide nitrogen coordinating to the palladium(II) ion.Crystal and molecular structure of disodium bis)N-tosylglycinato-N,O)palladate(II) - INORGANIC CHEMISTRY - n. volume 29 - pp. da 1293 a 1295 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal and molecular structure of Disodium bis(N-toluensulfonylglycinateN,O) palladate(II) compexes is determined. The structure consists of monomeric bis(N-toluensulfonylglycinateN,O) palladate(II) dianion and sodium cations. The coordination geometry around Pd(II) ions is planar and the aminoacidate moiety acts as bidentate chelate ligand by means of deprotonated sulfonyl nitrogen and one carboxylate oxygen.

L. Menabue; G. C. Pellacani; M. Saladini; M. Sola; L. P. Battaglia; A. Bonamartini Corradi; J. A. Cowan ( 1990 ) - Redox equilibria in metalloproteins and characterization of model complexes - Advances in Free Radicals in Disease - Cleup Padova ITA) - n. volume 2 - pp. da 199 a 209 ISBN: 9788871783420 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

This pepr deals with the redox properties of the copper site in superoxide dismutase and model complexes.

MENABUE L; SALADINI M ( 1990 ) - SIDE-CHAIN EFFECT ON THE COORDINATION BEHAVIOR OF GLYCINE DERIVATIVES TOWARD COPPER(II) - CRYSTAL-STRUCTURE OF BIS(MU-N-TRITYLGLYCINATO-O)-BIS[(2,2'-BIPYRIDINE)(N-TRITYLGLYCINATO-O)COPPER(II)] - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume nessun volume - pp. da 1581 a 1584 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal and molecular structure of the 2,2'-bipyridine (bipy) adduct of the violet copper(II) complexes with N-triphenylmethylglycine is reported. The structure consists of disceret dimeric [Cu(tglyO)2(bipy)2]2 with CuN2Os chromophores. The metal atoms are bridged through two unidentate carboxylate oxygens.

MENABUE L; SALADINI M; SOLA M ( 1990 ) - STABILIZING EFFECTS IN PD(II)-N-ARSO2-AMINO ACIDATE COMPLEXES - CRYSTAL AND MOLECULAR-STRUCTURE OF DISODIUM BIS(N-BENZENESULFONYLGLYCINATO-NO)PALLADATE(II) MONOHYDRATE - INORGANICA CHIMICA ACTA - n. volume 176 - pp. da 95 a 98 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal structure and 1H NMR study of Na2[Pd(BsglyNO)2]·H2O (BsglyNO=N-benzenesulfonylglycinate dianion) are reported. The crystals are monoclinic, space group P21/c with cell parameters: a=8.868(2), b=22.716(5), c=10.046(4) Å, β=98.07(3)°, Z=4. The structure consists of monomeric [Pd(BsglyNO)2]2− anions, sodium ions and lattice water molecules. The Pd atom shows a slightly distorted trans-coordination given by two independent BsglyNO dianions acting as bidentate ligands through one carboxylate oxygen and the deprotonated sulfonamide nitrogen. Intramolecular contacts of Pd with S, O and aromatic C atoms, and intramolecular stacking interactions involving phenyl rings are present. Some 1H NMR data in aqueous solution are also reported.

GAVIOLI GB; BORSARI M; MENABUE L; SALADINI M; PELLACANI GC; SOLA M ( 1990 ) - SULFONAMIDE NITROGEN-CONTAINING N-PROTECTED AMINO-ACIDS INTERACTING WITH PALLADIUM(II) - POLAROGRAPHIC AND PH-METRIC INVESTIGATION IN AQUEOUS-SOLUTION - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume . - pp. da 1585 a 1587 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

THE BEHAVIOUR OF SULFONAMIDE NITROGEN-CONTAINING N-PROTECTED AMINO-ACIDS INTERACTING WITH PALLADIUM(II) WAS INVESTIGATED THROUGH POLAROGRAPHIC AND PH-METRIC METHODS IN AQUEOUS-SOLUTION

GAVIOLI GB; BORSARI M; MENABUE L; SALADINI M; SOLA M; BATTAGLIA LP; CORRADI AB; PELOSI G ( 1990 ) - TERNARY COPPER(II) COMPLEXES WITH 2,2'-BIPYRIDINE AND N-TOSYL-SUBSTITUTED AMINO-ACIDS .1. POLAROGRAPHIC AND PH-METRIC STUDY - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume . - pp. da 91 a 95 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

TERNARY COPPER(II) COMPLEXES WITH 2,2'-BIPYRIDINE AND N-TOSYL-SUBSTITUTED AMINO-ACIDS WERE INVESTIGATED THROUGH POLAROGRAPHIC AND PH-METRIC METHODS

GAVIOLI GB; BORSARI M; MENABUE L; SALADINI M; SOLA M; BATTAGLIA LP; CORRADI AB; PELOSI G ( 1990 ) - TERNARY COPPER(II) COMPLEXES WITH 2,2'-BIPYRIDINE AND N-TOSYL-SUBSTITUTED AMINO-ACIDS .2. CRYSTAL AND MOLECULAR-STRUCTURE OF AQUA(2,2'-BIPYRIDINE)BIS(N-TOSYL-DL-ASPARAGINATO-O)COPPER(II) DIHYDRATE AND (2,2'-BIPYRIDINE)(N-TOSYL-DL-ASPARAGINATO-NO)COPPER(II) - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume . - pp. da 97 a 100 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

CRYSTAL AND MOLECULAR-STRUCTURE OF AQUA(2,2'-BIPYRIDINE)BIS(N-TOSYL-DL-ASPARAGINATO-O)COPPER(II) DIHYDRATE AND (2,2'-BIPYRIDINE)(N-TOSYL-DL-ASPARAGINATO-NO)COPPER(II) WERE DETERMINED

N.Masciocchi; M.Moret; A.Sironi; S.Bruni; F.Cariati; A.Pozzi; T.Manfredini; L.Menabue ; A.Benedetti ( 1989 ) - Coordinative capabilities of substituted propane-1,3-diamine: Zinc(II) halide adducts of 2,2-dimethylpropane-1,3-diamine. - INORGANICA CHIMICA ACTA - n. volume 159 - pp. da 173 a 180 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A series of compounds of formula Zn(dmpd)nX2· mH2O (dmpd = 2,2-dimethylpropane-1,3-diamine, X = Cl, Br, I; n = 2, m = 0; n = 3, m = 1) has been prepared and studied by means of spectroscopic (IR and Raman) and structural investigations. The [Zn(dmpd)2]I2 (I) compound crystallizes in the tetragonal P42/nmc space group, with two formula units in a cell of dimensions: a = b = 8.417(2), c = 12.726(2) Å. The structure consists of an ionic packing of iodide anions and of discrete [Zn(dmpd)2]2+ cations, where the Zn atoms are tetrahedrally coordinated to four nitrogen atoms of two chelating amine molecules. The [Zn(dmpd)3]Cl2·H2O (II) compound crystallizes in the triclinic space group P1, with Z = 2 and cell of dimensions: a = 9.021(2), b = 12.087(3), c = 13.785(3) Å, α = 59.01(2), β = 70.35(2), γ = 76.01(2)°. The crystal consists of an ionic packing of discrete [Zn(dmpd)3]2+ cations and chloride anions plus two clathrate water molecules per unit cell. The Zn atom presents a trigonal bipyramidal geometry, being surrounded by four nitrogen atoms of two chelating dmpd molecules and one nitrogen of a monodentate dmpd ligand. The structures were solved by conventional Patterson and Fourier methods and refined by full matrix least-squares to R and Rw of 0.053 and 0.073, and 0.040 and 0.046 for I and II respectively. The ZnN stretching vibrations are discussed and assigned in the light of the determined structures.

G.Ciani; M.Moret; A.Sironi; S.Bruni; F.Cariati; A.Pozzi; T.Manfredini; L.Menabue; G.C.Pellacani ( 1989 ) - Flexibility in coordinative behavior of propane-1,3-diamine toward Zn(II) and Cd(II) halides:[M(1,3pn)2X2 (M=Zn, Cd; X=Cl, Br,I)]. - INORGANICA CHIMICA ACTA - n. volume 158 - pp. da 9 a 16 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A series of compounds of formula M(1,3pn) 2X 2 (M Zn(II), Cd(II); 1,3pn=propane-1,3-diamine; X Cl, Br, I) has been prepared; two of them (M Zn, X Cl) and (M Cd, X I) have been structurally characterized. The Zn(1,3pn) 2Cl 2 (I) compound crystallizes in the P2 1/c space group, with eight formula units in a cell of dimensions: a=12.833(4), b=16.753(9), c=13.010(4) Å, β=118.88(3) °. The Cd(1,3pn) 2I 2 (II) compound crystallizes in the P2 1/n space group with four formula units. The structures were solved with the heavy-atom method and refined by full matrix least-squares to R and R w values of 0.029 and 0.038, 0.042 and 0.058 for I and II respectively. The asymmetric unit of I consists of a dimeric [Zn- (1,3pn) 2] 2 4+ moiety, where both Zn ions are tetrahedrally coordinated to four nitrogen atoms belonging to one chelating and two bridging 1,3pn ligands. The dimeric moiety generates an infinite chain upon translation of one cell in the direction of the diagonal (1,0,1). The structure of II shows a polymeric arrangement of octahedral Cd atoms sharing both iodine atoms and 1,3pn ligands. The MN stretching vibrations are discussed and assigned in the light of the known structures

L.Menabue; M.Saladini; P.Morini ( 1989 ) - Influence of 4-toluenesulphonyl group on the coordination properties of DL-asparagine and L-glutamine. - POLYHEDRON - n. volume 8 - pp. da 739 a 744 ISSN: 0277-5387 [Articolo in rivista (262) - Articolo su rivista]
Abstract

From the interaction between N-tosyl-dl-asparagine (TsasnH), N-tosyl-l-glutamine (TsglnH) (tosyl = 4-toluenesulphonyl) and copper(II) ion in aqueous solution, compounds of formula CuL2·XH2O·YC2H5OH (L = tosyl-α-aminoacidate monoanion), Cu(LH–1)·2H2O (LH–1 = tosyl-α-aminoacidate dianion) and K2[Cu(LH–1)2] were isolated. By potentiometric and spectrophotometric measurements, the number and type of complex species and their cumulative formation constants were determined. The treatment of data confirmed, also in solution, the formation of the complexes separated in the solid state and defined the pH range in which they are stable. The coordination behaviour of these ligands is compared with that of parent amino acids and other N-tosyl-derivatives.

G. Battistuzzi Gavioli; L. Menabue; M. Saladini; M. Sola; A. Bonamartini Corradi; L. P. Battaglia ( 1989 ) - Sulfonamide nitrogen containing, nitrogen protected aminoacids interacting with the Cd(II) ion. A 113Cd NMR and potentiometric study. X-ray diffraction of [Cd(ts-alfa-AlaO)2(H2O)4]. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume assente - pp. da 1345 a 1349 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Alfa-alanine and beta-alanine, N-protected by a tosyl group, bind Cd2+ acting initially as a simple carboxylate at low pH, and, at increasing pH, as N,O-bidentate ligands, through the carboxylic oxygen and the deprotonated amide nitrogen atoms.

L.Antolini; P.Baraldi; G.Marcotrigiano; L.Menabue; P.Morini; M.Saladini ( 1988 ) - Calorimetric and structural investigation of monomeric and dimeric copper(II)-N-protecetd aminoacidates - THERMOCHIMICA ACTA - n. volume 130 - pp. da 67 a 75 ISSN: 0040-6031 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A calorimetric investigation of the dehydration of structurally-known binary copper(II)-N-protected aminoacidates is reported to compare their relative stability. In order to consider a series of strictly related compounds, the crystal and molecular structure of N-benzoyl-α-alaninate (bz-α-ala) complex is also determined. The compound crystallizes in the triclinic space group P1− with 1 formula unit in a cell of dimensions a = 9.425(3), b = 9.579(3), c = 12.644 Å, α = 74.10(2)°, β = 78.95(2)°, γ = 88.32(3)°. The structure was solved using the Patterson and Fourier methods and refined by least-squares calculations to a conventional R factor of 5.6% for 3134 counter data. It consists of centrosymmetric tetracarboxylato bridged binuclear molecules showing the copper(II) acetate structure.The calorimetric analysis shows higher dehydration Ea values for dimeric species with respect to blue ones which assign a peculiar stability to dimeric structures. The crystal size strongly influences kinetic parameters because the proportion between water molecules on the surface and in the bulk varies with the crystal dimensions.

L.Antolini; L.Menabue; M.Saladini; L.P.Battaglia; A.Bonamartini Corradi; G.Micera ( 1988 ) - Co-ordination behaviour of N-protected aspartic acid in binary and ternary copper(II) complexes. Crystal and molecular structure of [N-acetyl-L-aspartato(2-)-O]-bis(2,2'bipyridine)copper(II)-ethanol tetrahydrate. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume not available - pp. da 909 a 012 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The complexes [Cu(bipy)2(acaspOO′)]·EtOH·4H2O(1), [Cu(bipy)2(bzaspOO′)]·2H2O (2) and [Cu(bipy)2(bzloaspOO′)]·EtOH·H2O (3)[bipy = 2,2′-bipyridine, acaspOO′=N-acetyl-L-aspartate (2–), bzaspOO′=N-benzoyl-L-aspartate (2–), and bzloaspOO′=N-benzyloxycarbonyl-L-aspartate (2–)] were synthesized. The crystal and molecular structure of (1) has been determined by X-ray diffraction. The compound crystallises in the space group P[1 with combining macron], with a= 12.947(4), b= 12.462(4), c= 11.152(3)Å, α= 115.44(6), β= 106.53(5), γ= 74.32(5)°, and Z= 2. The structure involves monomeric [Cu(bipy)2(acaspOO′)] units with the copper atom in a basically trigonal bipyramidal stereochemistry. The in-plane co-ordination is form a nitrogen atom of each bipy ligand and a β-carboxylate oxygen of the aspartate anion. Two nitrogen atoms, one from each bipy molecule, are the axial donors. The distortion is toward square-pyramidal stereochemistry with the oxygen atom at the apex. The second oxygen of the β-carboxylate group is at a distance of 2.875(8)Å from copper to give a 4 + 1 + 1* type co-ordination. The crystal packing is determined by hydrogen bonds between water molecules, α-carboxylate and acetyl groups, and ethanol molecules. The stack between symmetry related (and hence parallel) bipy moieties involves interatomic distances of 3.47 and 3.45 Å, respectively. Spectroscopic results suggest that the metal co-ordination geometry is the same in all the complexes

L.P.Battaglia; A.Bonamartini Corradi; A.Marzotto; L.Menabue; G.C.Pellacani ( 1988 ) - Coordinative abilities of ligands which favour S,S chelation: copper(I) halide complexes of N,N'-diphenyldithiomalonamide. The crystal and molecular structure of bis(N,N'-diphenyldithiomalonamide)copper(I) iodide-methanol (2/1). - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 1713 a 1718 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The spectroscopic (i.r. and n.m.r.) properties of [Cu(Hdpdma)2]X (Hdpdma = N,N′-diphenyldithiomalonamide; X = Cl, Br, or I) are discussed in the light of the structural results obtained for [Cu(Hdpdma)2]I·0.5MeOH. The compound crystallizes in the space group P1̄ of the triclinic system. In the unit cell two crystallographically independent [Cu(Hdpdma)2]+ cations, two iodine anions, and one methanol solvate molecule are present. The co-ordination around each copper atom is slightly distorted tetrahedral and involves four sulphur atoms belonging to two Hdpdma molecules, which act as bidentate neutral ligands and form two six-membered chelate rings. The i.r. study and the structural results, compared with those for other transition-metal complexes, permits some reasonable conclusions on the co-ordinative abilities of dithiomalonamides. The 1H and 13C n.m.r. results suggest that the same structural arrangement is maintained in solution.

G. Battistuzzi Gavioli; M. Borsari; G. C. Pellacani; L. Menabue; M. Sola ( 1988 ) - Effectiveness of the cadmium(II) ion in promoting nitrogen deprotonation. 113 Cd NMR, polarographic, and pH-metric investigations on the Cadmium(II)-N-tosyl-glycinate and Cadmium(II)-N-dansylglycinate systems in aqueous and methanolic systems - INORGANIC CHEMISTRY - n. volume 27 - pp. da 1587 a 1592 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

13Cd NMR, polarographic, and pH-metric investigations reveal the ability of the Cd2' ion in substituting for the nitrogen-boundhydrogen of the amino acids N-protected by a sulfonic group. In aqueous and methanolic solution, N-tosylglycine and Ndansylglycine interacting with the Cd2+ ion show a pH-dependent binding mode, at increasing pH changing from simple carboxylate to N,O-bidentate ligands. The overall equilibria involving the prevailing complexes are similar to those previously found with the Cu2+ ion, but the stability of the cadmium complexes is lower by factors ranging from IO to lo4. Two binary complexes of formula [CdL,(H,O),] (L = N-tosylglycinate, N-dansylglycinate) were separated in the solid state. X-ray powder spectra and IR data for the complex of N-tosylglycine show that it is isomorphous and isostructural with the analogous complexes with Zn2', Co2+, and Ni2+, in which the ligand is monodentate through the carboxylate group.

L.P.Battaglia; A.Bonamartini Corradi; A.Marzotto; L.Menabue; G.C.Pellacani ( 1988 ) - Nickel(II) and Palladium(II) complexes of dithiomalonamides: ligand which favor the formation of pi-conjugation systems in the coordination. - JOURNAL OF CRYSTALLOGRAPHIC AND SPECTROSCOPIC RESEARCH - n. volume 18 - pp. da 101 a 112 ISSN: 0277-8068 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The spectra (IR and NMR) of the nickel(II) and palladium(II) complexes of dithiomalonamide (Hdtma) and N,N′-diphenyldithiomalonamide (Hdpdtma) are discussed in the light of the structure of the bis(N,N′-diphenyldithiomalonamidato) nickel(II) di(N,N-dimethylformamide)solvate. The compound crystallizes in the triclinic space group P-1 (No. 2) with a=11.113(2), b=10.173(2), c=9.912(1) Å, a=74.47(6), β=108.83(7), γ=114.10(7)°, Z=1 (R=0.0495 and Rw=0.052). The crystals consist of discrete [Ni(dpdtma)2] and N,N-dimethylformamide (DMF) molecules. The nickel atom is chelated by two centrosymmetrically related ligands via sulfur atoms in an approximately squareplanar arrangement. The ligand moiety in the nickel coordination forms a π-conjugation system. The DMF solvate molecules are involved in hydrogen bonding with the NH groups of the ligand.

L.Menabue; M.Saladini ( 1988 ) - Structure of catena-poly{[-(N-acetyl-DL-valinato)O :O ]copper(II)}. - ACTA CRYSTALLOGRAPHICA. SECTION C - n. volume C44 - pp. da 2087 a 2089 ISSN: 1600-5759 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Crystal structure of [Cu(C7H12NO3)2]n is reported

L.P.Battaglia; A. Bonamartini Corradi; U.Geiser; R.D.Willett; A.Motori; F.Sandrolini; L.Antolini; T.Manfredini; L.Menabue; G.C.Pellacani ( 1988 ) - The crystal structure, magnetic and electrical properties of two polymeric chlorocuprate(II) compounds. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 265 a 271 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal structures of piperidinium trichlorocuprate(II) [Hpip][CuCl3], and piperazinium hexachlorodicuprate(II), [H2pipz][Cu2Cl6], have been determined by X-ray diffraction techniques. [Hpip][CuCl3] is monoclinic, space group C2/c, with a = 18.385(7), b = 8.439(4), c = 11.878(5) Å, and β = 103.63(5)° while [H2pipz][Cu2Cl6] is triclinic, P1, with a = 7.984(4), b = 7.054(4), c = 6.104(3) Å, α = 111.23(8), β = 99.95(9), γ = 81.26(7)°. Both salts contain infinite chains of [Cu2Cl6]2- dimers. The [Cu2Cl6]2- dimers show significant distortions from planarity due to formation of semi-co-ordinate bonds between adjacent dimers, with a larger distortion for the Hpip salt. This bifold distortion gives each copper(II) ion a (4 + 1) co-ordination geometry. The chains have slightly different configurations. In the H2pipz salt, adjacent dimers are related by unit-cell translations, while in the Hpip salt they are related by a c-glide operation. Magnetic susceptibility measurements show that the H2pipz salt is an alternating antiferromagnetic chain with J/k = -13.35(7) K and J′/k = -7.6(3) K, while the Hpip salt is an alternating ferro- antiferro-magnetic chain with J/k = 26(3) K and J′/k = -0.24(1) K. Thus, the intradimer coupling (J) becomes less antiferromagnetic as the distortion from planarity increases. Comparison with other bifolded dimers confirms correlation of J with the bifold angle, both experimentally and theoretically. Electrical measurements reveal the presence of an activated process for electrical conduction with activation parameters of 0.44 eV for [Hpip][CuCl3] and 0.34 eV for [H2pipz][Cu2Cl6]. The charge carriers are proposed to be the protons in N-H ⋯ Cl hydrogen bonds

L. Antolini; L. Menabue; M. Saladini; M. Sola ( 1988 ) - The effectiveness of carboxyl as primary ligating group in aryl-SO2 N-protected aminoacids-copper(II) systems: solution and structural investigation on the Cu(II)-N-tosyl-L-leucinate system. - INORGANICA CHIMICA ACTA - n. volume 152 - pp. da 17 a 23 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The interaction between N-tosyl-L-leucine (tosyl = 4-toluenesulphonyl) and the copper(II) ion in aqueous-methanolic solution was examined. Two compounds of formula Cu(tsleuO)2·4H2O and Na2[Cu(tsleuNO)2(H2O)]·2H2O·CH3OH [tsleuO = N-tosyl-L-leucinate(1−), tsleuNO = N-tosyl-L-leucinate(2−)] were isolated. For the second complex the crystal and molecular structure was also determined. The crystals were found to be monoclinic, space group P21 with Z = 2 in a unit cell of dimensions a = 16.775(2), b = 11.914(2), c = 9.053(2) Å, β = 100.54(1)°. Full matrix least-squares refinement using 2900 independent reflections reached R = 0.037. The structure is built up of one [Cu (tsleuNO)2(H2O)] dianion, two Na+ cations, two lattice water molecules and one methanol solvate molecule. The coordination about the Cu atom is a distorted square-pyramidal arising from ligation of two trans amino acidate dianions acting as N,O ligands in the basal plane, and of one water oxygen in the axial position. The crystal packing is determined by Na+---O interactions. By potentiometric and spectrophotometric measurements, the number and type of complex species and their cumulative formation constants were determined. The treatment of data confirmed, also in solution, the formation of the complexes separated in the solid state (stable, the first up to pH = 5 and the second above pH = 8). In addition, two complexes of formula [Cu(tsleuNO)] and [Cu(tsleuO)(tsleuNO)]− were found to prevail in the 5–8 pH range. The comparison of data with those of other aryl---SO2 N-substituted α-amino acids indicates the same behaviour towards deprotonation of nitrogen and the effectiveness of carboxyl as a primary ligating group in preventing metal hydrolysis.

L.Menabue; M.Saladini; L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano; P.Morini ( 1987 ) - Cobalt(II) and nickel(II) complexes of N-protected amino acids. Crystal and molecular structure of bis(Nacetylglycinato) tetraaquocobalt(II). - JOURNAL OF CRYSTALLOGRAPHIC AND SPECTROSCOPIC RESEARCH - n. volume 17 - pp. da 313 a 319 ISSN: 0277-8068 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this paper are reported structural and spectroscopic properties of (N-benzenesulphonylglycinato) triaquacopper (II) (complex I) and dipotassium bis (N-benzenesulphonylglycinato) cuprate (II) (complex II). The crystals of (I) are monoclinic, space groupP21/c,Z=4, withagr=12.736(4),b=10.292(3),c=10.402(3) Å,beta=109.41(2)° while those of complex (II) are orthorhombic, space groupPbca, witha=23.333(8),b=10.508(4),c=16.989(5) Å. In both complexes the aminoacid molecules act as bidentatevia carboxylic oxygen and the amide nitrogen atom; in (I) three water molecules complete the coordination to tetragonal pyramidal, while in (II) coordination is square planar, tetrahedrally distorted involving two ligand molecules. The structure (I) was refined to a finalR index of 0.0596 and (II) toR=0.0466.

L.Antolini; A.C.Fabretti; G.C.Franchini; L.Menabue; G.C.Pellacani; H.O.Desseyn; R.Dommisse; H.C.Hofmans ( 1987 ) - Dithiooxamides as ligands: crystal structures and vibrational analyses of bis(N,N'-dicyclohexyldithiooxamidato)palladium(II) bis(N,N'-dibenzyldithiooxamide)copper(II) diperchlorate, and dichloro(N,N'-dimethyldithiooxamide)zinc(II) and the carbon-13 nuclear magnetic resonance spectra of related compounds. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 1921 a 1928 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Three N,N′-disubstituted dithio-oxamide metal complexes [Pd(Hdcdto)2], [Cu(H2dbzdto)2][ClO4]2, and [Zn(H2dmdto)Cl2] (H2dcdto, H2dbzdto, and H2dmdto = N,N′-dicyclohexyl-, N,N′-dibenzyl-, and N,N′-dimethyl-dithio-oxamide respectively) have been prepared and their crystal and molecular structures determined for the first time. In all cases the N,N′-disubstituted dithio-oxamides act as S,S′-chelating ligands. The PdII and CuII ions show nearly idealized square-planar S4 co-ordination, and the ZnII ion a distorted tetrahedral S2Cl2 co-ordination geometry. The co-ordination ability of the organic ligands and the conformations of their chelate rings are discussed. The i.r. spectra of the complexes are discussed and compared with analogous compounds. The 13C n.m.r. spectra of related complexes have been recorded in the solid state and in solution. E.s.r. spectra of a series of copper(II) complexes are also discussed in the light of the covalent strength of the ligands.

L.Menabue; M.Saladini ( 1987 ) - Solution and solid state investigation ofthe Cu(II)-N-acetyl-L-glutamine system and its N-methylimidazole adduct. - INORGANICA CHIMICA ACTA - n. volume 135 - pp. da 49 a 53 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The interactions of N-acetyl-L-glutamine (AcglnH) with copper(II) ion in aqueous and water-methanol (50% v/v) solutions and in solid state have been investigated. It was found that the N-acetyl-L- glutaminate anion (Acgln) is unable to form stable complexes in solution on varying the pH values, before copper(II) hydroxyde precipitation occurs. In the solid state two compounds of the formulas Cu(Acgln)2·2H2O and Cu(Acgln)2(MeIm)2·2H2O (MeIm = N-methylimidazole) are separated; for the latter complex the crystal and molecular structure was determined by means of the single crystal X-ray diffraction method. The compound crystallizes in the monoclinic space group C2, with cell dimensions: a = 15.606(7), b = 7.353(2), c = 13.951(2) Å, β = 110.69(3)° and Z = 2. The structure was solved by conventional Patterson and Fouder methods and refined by full-matrix least-squares to an R value of 0.026. The structure consists of [Cu(Acgln)2(Me- Im)2] units and uncoordinated watet molecules. The Cu(II) atom lying on the twofold axis exhibits a square-planar N2O2 environment from ligation by two symmetry-related carboxytate oxygens and N-methylimidazole nitrogens. The second non- bonding carboxylate oxygens are 2.813(3) Å from the Cu(II) atom and both are placed under the coordination plane. Spectroscopic and thermal results agree with the crystal stmcture, while for binary Cu(Acgln)2·2H2O a CuO4 chromophore is suggested.

L. P. Battaglia; A. Bonamartini Corradi; L. Menabue; M. Saladini; M. Sola ( 1987 ) - Spectroscopic, magnetic, and structural properties of diaquadimethanolbis-(N-tosylvalinato)copper(II) and its 2,2'-bipyridine adduct - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - pp. da 1333 a 1339 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Binary copper(II) compounds of N-tosylvalinate of formula [Cu(tsvalO)2(H2O)2]4H2O and [Cu(tsvalO)2(H2O)2(MeOH)2] were separated. The structure of the latter consists of discrete [Cu(tsvalO)2(H2O)2(MeOH)2] units in which the copper ion, lying on the symmetry centre, is surrounded by two carboxylic oxygens and two water molecules centrosymmetrically related. Two methanol molecules complete the co-ordination which is elongated tetragonal bipyramidal. The spectroscopic properties are consistent with a CuO6 chromophore. (...)

L.Antolini; L.Menabue; M.Saladini; L.P.Battaglia; A.Bonamartini Corradi ( 1987 ) - Structural and spectroscopic study on imidazole-copper(II)-N-protected amino acid complexes. Crystal and molecular structure of tetrakis(imidazole) coppper(II)bis(N-tosylvalinate). - JOURNAL OF CRYSTALLOGRAPHIC AND SPECTROSCOPIC RESEARCH - n. volume 17 - pp. da 365 a 372 ISSN: 0277-8068 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A pink-red air-stable, crystalline compound of empirical formula [Cu(Im)4(N-tsval)2] (Im=imidazole; ts=4-toluenesulfonyl group, hereafter abbreviated as tosyl;N-tsval=N-tosylvalinate monoanion) was synthesized and characterized by means of structural and spectroscopic measurements. The crystal structure of the compound was determined from three-dimensional diffractometer data. The crystals are monoclinic, space groupC2/c, a=18.952 (5),b=12.372 (2),c=17.594 (3) Å,beta=93.77 (2)°,Z=4. The structure was solved by the heavy-atom method and refined through least-squares calculations toR=0.035 for 2284 observed reflections. The coordination about the copper atom is elongated octahedral, with four imidazole molecules as equatorial ligands and two sulfonic oxygens in axial positions.

T.E.Grigereit; B.L.Ramakrishna; H.L.Place; R.D.Willett; G.C.Pellacani;T.Manfredini; L.Menabue; A.Bonamartini Corradi; L.P.Battaglia ( 1987 ) - Structures and magnetic properties of trinuclear copper(II) halide salts - INORGANIC CHEMISTRY - n. volume 26 - pp. da 2235 a 2243 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal structures of a series of trinuclear copper(II) halide salts have been determined. These all contain pseudoplanar, symmetrically bibridged Cu3X82- (Ia) or Cu3X7L- (Ib) anions. A2Cu3Cl8 or A2Cu3Cl8 salts are formed with A being the (Chemical Equation Presented) N-methylpiperazinium (NMPZ), 3-methyl-2-aminopyridinium (3MAP), and 5-methyl-2-aminopyridinium (5MAP) cations. A Cu3Br83- analogue is found with the 5-bromo-6-methyl-2-aminopyridinium (5B6MAP) cation. With the methylphenethylammonium (NMPH) cation, a (NMPH)Cu3Cl7·EtOH salt is isolated. The salts are all monoclinic with the following space group and lattice constants: NMPZ, C5H14N2Cu3Cl8, P21/c, a = 6.840 (3) Å, b = 14.321 (9) Å, c = 9.890 (5) Å, β = 102.90 (5)°, Z = 4; 3MAP, C12H18N4Cu3Cl8, C2/c, a = 26.05 (1) Å, b = 13.687 (4) Å, c = 7.099 (3) Å, β = 117.95 (3)°, Z = 4; NMPH, C11H20NOC3Cl7, P21/n, a = 11.843 (4) Å, b = 7.626 (3) Å, c = 23.840 (10) Å, β = 79.61 (3)°, Z = 4; 5B6MAP, C12N10N4-Cu3Br10, P21/n, a = 13.216 (3) Å, b = 4.076 (1) Å, c = 24.614 (6) Å, β = 91.65 (2)°, Z = 2. Each copper ion extends its primary coordination by formation of two semicoordinate bonds to halide ions in adjacent oligomers, yielding the familiar 4+2 coordination geometry for copper(II) complexes. These additional linkages cause the oligomers to aggregate into stacks, yielding stacking patterns of type IIa (NMPZ, 3MAP salts) or type IIb (NMPH, 5MAP, and 5B6MAP). Cu-X distances are approximately 2.3 (Figure Presented) Å (Cl) or 2.4 Å (Br) within the oligomers and 2.7-3.3 Å (Cl) or 3.2-3.3 Å (Br) between oligomers. The bridging Cu-X-Cu angles within the trimer average near 94°. Magnetic susceptibility measurements have been made on the NMPZ, NMPH, 3MAP, and 5MAP chloride salts. In addition, measurements were performed on Cu3Cl6(CH3CN)2, which contains neutral trinuclear oligomers. All compounds have doublet ground states arising from antiferromagnetic exchange coupling between neighboring copper(II) ions. The value of J/k is typically -20 to -35 K, consistent with the structural characteristics of the trimeric species

L.Menabue; M.Saladini; L.P.Battaglia; A.Bonamartini Corradi ( 1987 ) - The factors stabilizing square-planar geometries in -bonding amine adducts: crystal and molecular structure of bis(N-tosyl--alaninato)bis(piperidine)copper(II). - INORGANICA CHIMICA ACTA - n. volume 138 - pp. da 127 a 130 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A violet, air-stable, crystalline compound of empirical formula [Cu(Ts-β-ala)2(pipd)2] (Ts=4- toluene sulfonyl group, hereafter abbreviated as tosyl group, Ts-β-ala=N-tosyl-β-alaninate ion, pipd = piperidine) was synthesized and characterized by means of structural and spectroscopic measurements. The crystal structure of the compound was determined from three-dimensional diffractometric data. The crystals are triclinic, space group PView the MathML source, a = 9.305(1), b = 9.637(2), c = 12.727(2) Å, α = 61.50(2), β = 63.26(1), γ = 71.68(1)°, Z = 1. The structure was solved by the heavy atom method and refined through least-squares calculations to R = 0.032 for 2911 observed reflections. The copper atom lies on the symmetry center coordinating two piperidine and two carboxylic oxygens of N-tosyl-β-alanine in a square-planar arrangement. The second carboxylic oxygen is not involved in metal coordination. Electronic data are also discussed in comparison with those of other ternary Cu(II) carboxylate amine complexes.

L.Antolini; L.P.Battaglia; A.Bonamartini Corradi; L.Menabue; G.Micera; M.Saladini ( 1986 ) - Coordination behavior of N-protected aspartic acid in binary and ternary copper(II) complexes. Crystal and molecular structure of bis(2,2'-bipyridine)- bis(-N(benzyloxyvarbonyl)-L-aspartato-O,O',O")dicopper(II) 2.5water 0.5sodium perchlorate. - INORGANIC CHEMISTRY - n. volume 25 - pp. da 3301 a 3306 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The complexes [Cu(Z-asp)(H2O)]n 0,5NaClO4 were synthesized and characterized by means of spectroscopic and magnetic measurements.

L.P. Battaglia; A.B. Corradi; L. Antolini; T. Manfredini; L. Menabue; G.C. Pellacani; G. Ponticelli ( 1986 ) - Crystal and molecular structure of [H3N(CH2)2NH2(CH2) 2NH3]2HgCl8: A compound containing a discrete axially-compressed trigonal-bipyramidal pentachloromercurate anion - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 2529 a 2533 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The compound [NH3(CH2)2NH2(CH2) 2NH3]2HgCl8 has been prepared and investigated by an X-ray structural analysis and vibrational spectroscopy. The compound crystallizes with two formula units in space group P2/n of the monoclinic system in a cell of dimensions a = 11.530(2), b = 6.638(1), c = 15.028(3) Å, β = 93.00(2)°, and Z = 2. The crystal structure was determined by threedimensional X-ray diffraction and refined to R = 0.048, R′ = 0.051. The structure consists of diethylenetriammonium cations, chloride anions and discrete [HgCl5]3- anions. Co-ordination around the metal, which lies on the two-fold axis, can be described as a compressed trigonal bipyramid, where the equatorial positions are occupied by three weakly bonded chlorine atoms, two of them related by the two-fold axis [Hg-Cl(2) 3.029(3) Å]. The apices of the bipyramid are occupied by two shortly bonded chlorine atoms [Hg-Cl(1) 2.327(4) Å]. This is an example of a trigonal-bipyramidal d10 metal ion in which the axial bonds are significantly shorter than the equatorial bonds. Therefore it may be considered to consist of a linear HgCl2 molecule, with a bond angle [Cl(1)-Hg-Cl(1′) 178.8(1)°] perturbed by the interaction of three weakly bonded chlorine atoms. Packing is determined by a network of hydrogen bonds involving the diethylenetriammonium cation and co-ordinated and unco-ordinated chlorine atoms. The vibrational spectra of the [HgCl5]3- anion are rationalized in terms of D3h symmetry and a correlation between the values of mercury-chlorine stretching frequencies and the related bond distances in HgCl2 units is also discussed.

L. Antolini; L. Menabue; M. Sola; L. P. Battaglia; A. Bonamartini Corradi ( 1986 ) - The effect of a dansyl group on the coordinative ability of N-protected amino acids. Part 2. Binary copper(II) complexes and their pyridine and 2,2'-bipyridine adducts. Crystal and molecular structure of the complexes aquabis(N-dansylglycinato-O)bis(pyridine)copper(II) and (2,2'-bipyridine)-(N-dansylglycinato-NO)(methanol)copper(II), and neutral N-dansylglycine - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - pp. da 1367 a 1373 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some binary Cu(II) complexes with N-dansylglycine and their ammine adducts with pyridine and 2,2'-bipyridine have been synthesized. (...)

L. Antolini; L. P. Battaglia; A. Bonamartini Corradi; G. Marcotrigiano; L. Menabue; G. C. Pellacani; M. Saladini; M. Sola ( 1986 ) - Tridentate facially coordinated L-aspartate ion complexation with the copper(II) ion: spectroscopic and structural properties of aqua(L-apartato)(1,10-phenantroline)copper(II) tetrahydrate - INORGANIC CHEMISTRY - n. volume 25 - pp. da 2901 a 2904 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this paper we report the synthesis and spectroscopic andstructural investigations on the mononuclear aqua(L-aspartato)(1 ,lo-phenanthroline)copper( 11) tetrahydrate complex.The results are discussed in comparison with the data obtainedfor the other mononuclear complexes aqua(~-aspartato)(2,2'-bipyridine)copper(II) trihydrate4 and aqua(L-glutamate) lOphenanthroline)copper(II) trihydrate,2 previously investigated.

ANTOLINI L.; BATTAGLIA L.P.; BONAMARTINI CORRADI A.; MARCOTRIGIANO G.; L. MENABUE; PELLACANI GC. ( 1985 ) - a- and b-carboxylic groups as primary ligating groups in promoting amide deprotonation. Solid state behavior of N-tosylalaninate-copper(II) complexes: crystal and molecular structure of bis(N-tosyl-b-alaninato)bsi(imidazole)copper(II), polymeric (N-tosyl-a-alaninato)diaquacopper monohydrate and dipiperidinium bis(N-tosyl-a-alaninato) copper(II) monohydrate complexes. - American Chemical Society:1155 Sixteenth Street Northwest:Washington, DC 20036:(800)227-5558, EMAIL: service@acs.org, INTERNET: http://www.pubs.acs.org, Fax: (614)447-3671 ) - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - n. volume 107 - pp. da 1369 a 1375 ISSN: 0002-7863 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The synthesys and crystal structure of three copper complexes with N-tosyl-aminoacids are reported. N-tosyl-a-alanine acts as bidentate chelate ligand through one carboxylic oxygen and the deprotonated nitrogen both in binary and ternary complexes, while N-tosyl-b-alanine acts as carboxylate monodentate ligand. The ability of a-alanine to form a stable five memebered chelate ring enables it to deprotonate and coordinate to to the metal by means of the nitrogen atom.

L.Antolini; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1985 ) - Coordination behavior of L-glutamic acid: spectroscopic and structural properties of (L-glutamato)(imidazole)copper(II), (L-glutamato)(2,2'-bipyridine)copper(II) and aqua(L-glutamato) (1,10-phenanthroline)copper(II) trihydrate complexes. - INORGANIC CHEMISTRY - n. volume 24 - pp. da 3621 a 3626 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The synthesis and structural and spectroscopic characterization of three ternary copper(I1)-L-glutamate complexes of formulasCu(L-glu)(im), Cu(r-glu)(bpy), and Cu(~-glu)(o-phen).4H~(OL -glu = L-glutamate ion; im = imidazole; bpy = 2,2’-bipyridine;o-phen = 1 ,lo-phenanthroline) are described. The Cu(L-glu)(im) complex has a one-dimensional polymeric structure, due to thebridging by the glutamate ligand between square-planar copper ions. The same polymeric structure and the same metal bindingby the glutamate ion occur in the Cu(L-glu)(bpy) complex, but in a square-pyramidal geometry. The structure of [CU(Lglu)(o-phen)H20].3H20 is made up of discrete mononuclear units, in which the glutamate ion acts as a simple bidentate ligandtoward a s uare pyramidal Cu atom.The synthesis and structural and spectroscopic characterization of three ternary copper(I1)-L-glutamate complexes of formulasCu(L-glu)(im), Cu(r-glu)(bpy), and Cu(~-glu)(o-phen).4H~(OL -glu = L-glutamate ion; im = imidazole; bpy = 2,2’-bipyridine;o-phen = 1 ,lo-phenanthroline) are described. The Cu(L-glu)(im) complex has a one-dimensional polymeric structure, due to thebridging by the glutamate ligand between square-planar copper ions. The same polymeric structure and the same metal bindingby the glutamate ion occur in the Cu(L-glu)(bpy) complex, but in a square-pyramidal geometry. The structure of [CU(Lglu)(o-phen)H20].3H20 is made up of discrete mononuclear units, in which the glutamate ion acts as a simple bidentate ligandtoward a s uare pyramidal Cu atom.The synthesis and structural and spectroscopic characterization of three ternary copper(I1)-L-glutamate complexes of formulasCu(L-glu)(im), Cu(r-glu)(bpy), and Cu(~-glu)(o-phen).4H~(OL -glu = L-glutamate ion; im = imidazole; bpy = 2,2’-bipyridine;o-phen = 1 ,lo-phenanthroline) are described. The Cu(L-glu)(im) complex has a one-dimensional polymeric structure, due to thebridging by the glutamate ligand between square-planar copper ions. The same polymeric structure and the same metal bindingby the glutamate ion occur in the Cu(L-glu)(bpy) complex, but in a square-pyramidal geometry. The structure of [CU(Lglu)(o-phen)H20].3H20 is made up of discrete mononuclear units, in which the glutamate ion acts as a simple bidentate ligandtoward a s uare pyramidal Cu atom.Spectroscopic (EPR, IR, and vis) properties of the complexes are interpreted in the lightof the known structures. The polymeric ability of the L-glutamate and L-aspartate ions in the presence of the copper(I1) ion is also discussed

L. Antolini; G. Marcotrigiano; L. Menabue; G. C. Pellacani; M. Saladini; M. Sola ( 1985 ) - Coordination behavior of L-Glutamic acid: Spectroscopic and structural properties of (L-Glutamato)(imidazole)copper(II), (L-glutamato)(2,2'-bipyridine)copper(II), and aqua(L-glutamato)(1,10-phenanthroline)copper(II) tryhydrate complexes - INORGANIC CHEMISTRY - n. volume 24 - pp. da 3621 a 3626 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The synthesis and structural and spectroscopic characterization of three ternary copper(I1)-L-glutamate complexes of formulasCu(L-glu)(im), Cu(r-glu)(bpy), and Cu(~-glu)(o-phen).4H~(OL -glu = L-glutamate ion; im = imidazole; bpy = 2,2’-bipyridine;o-phen = 1 ,lo-phenanthroline) are described. The Cu(L-glu)(im) complex has a one-dimensional polymeric structure, due to thebridging by the glutamate ligand between square-planar copper ions. The same polymeric structure and the same metal bindingby the glutamate ion occur in the Cu(L-glu)(bpy) complex, but in a square-pyramidal geometry. The structure of [CU(Lglu)(o-phen)H20].3H20 is made up of discrete mononuclear units, in which the glutamate ion acts as a simple bidentate ligandtoward a s uare pyramidal Cu atom. Crystal data are as follows. [CU(L-glu)(im)]: orthorhombic, space group P2,2,2,, a =24.286 (2)I$r, b 8.604 (1) A, c = 5.075 (1) A, Z = 4, R = 0.044 for 831 observed reflections. [Cu(r-glu)(bpy)]: orthorhombic,space group P2,2,2,, a = 7.674 (1) A, b = 17.738 (4) A, c = 21.761 (5) A, 2 = 8, R = 0.077 for 2129 reflections. [CU(Lglu)(o-phen).HzO].3H20: monoclinic, space group P2,, a = 12.168 (2) A, b = 22.222 (3) A, c = 7.591 (1) A, 0 = 106.10 (2)O,2 = 4, R = 0.049 for 3554 reflections. Spectroscopic (EPR, IR, and vis) properties of the complexes are interpreted in the lightof the known structures. The polymeric ability of the L-glutamate and L-aspartate ions in the presence of the copper(I1) ion isalso discussed.

L.Antolini; L.Menabue; M.Saladini ( 1985 ) - Coordination behavior of 4-toluenesulfonamide derivatives: thermal,magnetic, spectroscopic and structural properties of bis(p-N-tosylglycinato-O)- bis(N-tosylglycinato-O)bis (2,2'-bipyridine)dicopper(II)dihydrate . - INORGANIC CHEMISTRY - n. volume 24 - pp. da 1219 a 1222 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The compound of formula [Cu(TsGlyH)2(bpy)2]2H2O was synthesuized and characterized by means of structural, spectroscopic, thermal and magnetic measurements.

A. Colombo;L. Menabue; A. Motori; G.C. Pellacani; W. Porzio; F. Sandrolini; R.D. Willett ( 1985 ) - Crystal structure and spectroscopic, magnetic, and electrical properties of a copper(II) dimer, melaminium hexachlorodicuprate(II), exhibiting a new stacking interaction - INORGANIC CHEMISTRY - n. volume 24 - pp. da 2900 a 2905 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The (C 3N 6H 8)Cu 2Cl 6 compound (C 3N 6H 8 = melaminium dication, hereafter abbreviated as melH 2) has been synthesized and its crystal structure determined. A number of its physical properties were examined, including its electronic and vibrational spectra, as well as magnetic and electrical behavior. The crystals are monoclinic, space group P2 1/c, with a = 6.6600 (1) Å, b = 10.0598 (2) Å, c = 19.2691 (12) Å, β = 96.011 (3)°, Z = 4, d calcd = 2.42 g·cm -3, and d measd = 2.45 g·cm -3. The structure, solved by direct methods and refined by least-squares calculations to R = 3.9%, consists of melaminium dications and Cu 2Cl 6 2- dimers stacked to form infinite chains in a manner not previously observed. The coordination of the copper atoms may be described as distorted square pyramidal. Electronic and vibrational results are discussed on the basis of the crystal structure. The compound exhibits predominantly antiferromagnetic exchange interactions. An intradimer singlet-triplet energy splitting of ΔE/k = 54 K is deduced, with weaker ferromagnetic coupling between dimers. A comparison with the magnetic behavior of other Cu 2Cl 6 2- dimers is given. Electrical conductivity measurements classify the compound as an insulating material

L. P. Battaglia; A. Bonamartini Corradi; L. Menabue; M. Saladini; M. Sola; G. Battistuzzi Gavioli ( 1985 ) - Solution and solid state behavior of Co(II), Ni(II) and Zn(II) tosylaminoacidate systems: crystal and molecular structure of Bis(N--tosylclycinato)tetraaquocobalt(II) and Bis(N-tosyl-beta-alaninato)tetraaquozinc(II) complexes - INORGANICA CHIMICA ACTA - n. volume 107 - pp. da 73 a 79 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The interactions between N-tosylamino acids and cobalt(II), nickel(II) and zinc(II) ions in aqueous solution and in the solid state have been investigated. From concentrated aqueous solutions, compounds of general formula [M(II)(N-tosylaminoacidato)2(H2O)4](M = Co(II), Ni(II) and N-tosylaminoacidato = N-tosylglycinate (Tsgly−), N-tosyl-α- and -β-alaninate (Ts-α- and Ts-β-ala−); M = Zn(II) and N-tosylaminoacidate = Tsgly−, Ts-β-ala−) and [Zn(II)(N- tosylaminoacidato)2(H2O)2] were isolated and characterized by means of thermogravimetric, electronic and infrared spectra. For two of them: [Co(Tsgly)2(H2O)4](I) and [Zn(Ts-β-ala)2(H2O)4](II) the crystal and molecular structures were also determined. Both compounds crystallize in the monoclinic space group P21/c, with two formula units in a cell of dimensions: a = 13.007(6), b = 5.036(2), c = 18.925(7) Å, β = 102.33(3)° for (I) and a = 14.173(6), b = 5.469(2), c = 17.701(7) Å, β = 106.63(3)° for (II). The structures were solved by the heavy-atom method and refined by least-squares calculations to R = 0.031 and 0.064 for (I) and (II) respectively. The cobalt and zinc atoms lie in the centers of symmetry, each bonded to two amino- acid molecules through a carboxylic oxygen atom and four water molecules in a slightly tetragonally distorted octahedral geometry. The second carboxylic oxygen atom is not involved in metal coordination. Electronic and X ray-powder spectra suggest that the tetrahydrate complexes of Co2+, Ni2+ and Zn2+ ions of the same amino acids are isomorphous and isostructural. No coordinative interactions between ligand and metal ions were found in aqueous solution on varying the pH values before hydroxide precipitation.

G. Battistuzzi Gavioli; G. Grandi; L. Menabue; G. C. Pellacani; M. Sola ( 1985 ) - The effect of a dansyl group on the coordinative ability of N-protected amino acids. Part 1. Behaviour of the copper(II) ion-N-dansylglycinate system in aqueous and methanolic solution - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - pp. da 2363 a 2368 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Polarographic, potentiometric and spectrophotometric measurements show that copper(II) and N-dansylglycine form the same complexes in aqueous and methanolic solution. Mixed-hydroxy complexes are the prevailing species. In aqueous (methanolic) solution up to pH 5 (5) no formation of complexes is observed; in the pH range 7-8.5 (8.5-11) a change in ligand coordination from O-coordination through the carboxylate group to N,O-bidentate coordination through the carboxylate oxygen and the deprotonated amide nitrogen is revealed. There is a low tendency for two N-dansylglycine ligand molecules to coordinate to the Cu(II) ion, probably due to the steric hindrance of the dansyl group. The equilibria in which the prevailing complexes are involved and the reduction processes at the electrode are proposed. The nucleophilic and electrophilic properties of the two solvents are used to explain the solvent effect on the polarographic parameters and on the stability constants of the complexes.

L.Antolini; L.Menabue ( 1984 ) - Coordination behavior of 4-toluenesuphonamide derivatives: thermal, and spectroscopic properties of (N-tosylglycinato)(2,2'-bipyridine)copper(II) complexes. Crystal and molecular structure of (ethanol) (N-tosylglycinato)(2,2'-bipyridine)copper(II). - INORGANIC CHEMISTRY - n. volume 23 - pp. da 1418 a 1422 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The compounds of formula [Cu(Tsgly)(bpy)L] and anhydrous [Cu(Tsgly)(bpy)] (Tsgly = N-tosylglycinate dianion; bpy= 2,2’-bipyridine;L = EtOH, H20)w ere synthesized and characterized by means of thermogravimetric, electronic, infrared,and EPR spectra. For one of them, the [Cu(Tsgly)(bpy)(EtOH)] complex, the crystal structure was also determined. The structure consists of discrete molecular unitsof [Cu(Tsgly)(bpy)(EtOH)]. The Cu atom shows tetrahedrally distorted square-pyramidal N3O2 coordination. The Tsglydianion and the bpy molecule act as bidentate ligands in the equatorial plane, and the ethanol is bonded to the metal atomin the apical position. The thermogravimetric, EPR, and electronic results for the aquo and ethanol derivatives suggestthat the stability of the in-plane ligands permits successive substitution reactions at the apical position. The infrared spectrafor the aquo and ethanol adducts are consistent with the presence of a coordinated water or ethanol molecule.

L. Antolini; L. Menabue; M. Saladini; M. Sola; L. P. Battaglia; A. Bonamartini Corradi ( 1984 ) - Imidazole-containing ternary complexes of N-benzyloxycarbonyl-aminoacids. Crystal and molecular structure of bis(N-benzyloxycarbonyl-alaninato)bis-(N-methylimidazole)copper(II) ethanol solvate - INORGANICA CHIMICA ACTA - n. volume 93 - pp. da 61 a 66 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Mixed ligand complexes of the type Cu(Z-amino-acidato)2(B2) were synthesized and characterized by means of electronic, infrared and EPR spectroscopies. For one of them, the crystal and molecular structure was also determined by the single crystal X-ray diffraction method. ...

L.Antolini; L.Menabue; G.C.Pellacani; M.Saladini; L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano ( 1984 ) - Magnetic and spectroscopic properties of dimeric copper(II) complexes of N-benzyloxy carbonyl -substituted amino acid anions. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume not available - pp. da 2325 a 2326 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

N-Benzyloxycarbonyl-substituted amino acids (HL) react with the copper(II) ion to form simple green complexes of formula [{CuL2(H2O)n}2](L =N-benzyloxycarbonyl-glycinate, -valinate, or -leucinate, n= 1; L =N-benzyloxycarbonylalaninate, n= 0), which show physical properties indicating a dimeric structure with strong antiferromagnetic interactions between the copper(II) ions within the pairs through a superexchange mechanism via bridging carboxylate groups. Exchange integrals (–2J) in the range 295–350 cm–1 were calculated.

L.Antolini; L.Menabue; G.C.Pellacani; G.Battistuzzi Gavioli; G.Grandi; L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano ( 1984 ) - Solid state and ethanolic solution behavior of N-tosylglycinate-copper(II) complexes. Crystal and molecular structure of a strongly coupled polymeric N-tosylglycinato copper(II) complex. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 1687 a 1692 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The interaction between N-tosylglycine and the copper(II) ion in ethanolic solution has been examined. Two compounds of formula [{Cu(tsglyO)2}n](green) and Na2[Cu(tsglyNO)2](blue)(tsglyO and tsglyNO =N-tosylglycinate monoanion and dianion, respectively) were isolated. Crystals of [{Cu(tsglyO)2}n] are monoclinic, space group P21/n with Z= 4 in a unit cell of dimensions a= 24.655(3), b= 7.697(2), c= 12.378(3)Å, and β= 87.34(8)°. Full-matrix least-squares refinement, using 1 677 independent reflections, reached R= 0.052. The structure is built up of one-dimensional polymeric chains of binuclear units, showing the copper(II) acetate structure, linked via Cu–O(sulphonic) bonds. Its magnetic and spectroscopic properties are interpreted on the basis of the crystal structure. In particular it shows an exchange integral (–2J) of 353 ± 4 and a zero-field splitting, D, of 0.35 cm–1. The i.r. spectrum shows multiple sulohonamide absorotion bands because only half of the SO2grouos are co-ordinated. By polagraphic measururements in ethanol, the number and type of complex species, the equilibria in which they are involved, and their stability constants have been determined. For cnaOH/ccomplexrations between 1 and 3 the species [cu(tsglyO)2] is the only one persent; for ratios >4, [cu(tsglyO)2]2– prevails.

L.Antolini; L.Menabue; M.Saladini; L.P.Battaglia; A.Bonamartini Corradi ( 1984 ) - Spectroscopic and structural investigation on two (2,2'-bipyridyl) bis(N-protected aminoacidato)copper(II) complexes. Two compounds containing truly CuN202 chromphore. - INORGANICA CHIMICA ACTA - n. volume 90 - pp. da 97 a 103 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The compounds of formula [Cu(bipy)(acleuO)2] (1) and [Cu(bipy)(ts-β-alaO)2] (2) (bipy = 2,2′-bipyridil, acleuO = N-acetyl-DL-leucinate anion, ts-β-alaO = N-tosyl-β-alaninate anion) were synthesized and characterized by means of spectroscopic and structural measurements. Complex (1) crystallizes in the monoclinic space group C2/c with cell parameters a = 17.465(4), b = 19.740(5), c = 9.080(2) Å, β = 115.0(1)° with Z = 4; complex (2) crystallizes in the triclinic space group PView the MathML source, with cell parameters a = 14.489(3), b = 14.308(3), c = 8.659(1) Å, α = 75.0(1), β = 74.6(1), γ = 66.6(1)°, Z = 2. Both structures were solved by conventional Patterson and Fourier methods and refined to R factors of 4.10 and 3.8% respectively. In both crystals the Cu atom is four-coordinated by the nitrogen atoms of a bipy molecule and two carboxylate oxygens of two N-protected aminoacid anions acting as unidentate ligands. The only significant difference between the coordination geometry of (1) and (2) is in the tetrahedral distortion of the coordination plane. Complex (2) is strictly planar, while in complex (1) the distortion expressed by the dihedral angle between the (N)(1)CuN(1′) and O(1)CuO(1′) planes is 20.8°. The electronic and EPR results agree with these different coordination geometries. The infra-red data are consistent with a truly monodentate carboxylate group. The spectroscopic results on a series of previously investigated [Cu(bipy)(N-protected aminoacidato)2] complexes of unknown structures are discussed again in the light of the present structural reports.

J. Giusti; G.G.T. Guarini; L. Menabue; G.C. Pellacani ( 1984 ) - Thermal behaviour of [N(2-ammoniumethyl) piperazinium] pentachlorocuprate(II) dihydrate - JOURNAL OF THERMAL ANALYSIS - n. volume 29 - pp. da 639 a 643 ISSN: 0368-4466 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal behaviour of single-crystals of the title compound has been investigated by means of thermal methods supported by optical microscopy. A complex change takes place on heating. After the loss of the two water molecules, leading to an amorphous phase, recrystallization takes place. This results in a solid (probably an anhydrous form) which reacts further, through partial liquefaction, to yield a red crystalline product whose structure has been characterized via X-ray powder spectra and electronic and IR spectroscopy

L.Menabue; G.C. Pellacani; L.P. Battaglia; A.B. Corradi; F. Sandrolini; A. Motori; R.J. Pylkki; R.D. Willett ( 1984 ) - Thermochromism in copper(II) complexes: Spectroscopic, thermal, and electrical properties and room-temperature crystal structure of bis(2,2-dimethylpropane-1,3-diamine)copper(II) dinitrate - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 2187 a 2192 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The compound bis(2,2-dimethylpropane-1,3-diamine)copper(II) dinitrate, Cu(dmpd)2(NO3)2, undergoes a first-order thermochromic phase transition at 142 °C, changing colour from blue-violet to blue upon heating. The crystal structure determination of the low-temperature phase demonstrates that the copper ion has a distorted (4 + 2) octahedral geometry, with the two six-membered chelate rings forming the basal plane (Cu-N = 2.020, 2.029 Å), and oxygens from the two nitrate groups weakly co-ordinated in the fifth and sixth co-ordination sites (Cu-O = 2.566 Å). The i.r. data have been interpreted in terms of the presence of semi-co-ordinated nitrate ions in the low-temperature phase and of unco-ordinated nitrate ions in the high-temperature phase. The electronic spectra reveal a weakening of the ligand field in the high-temperature phase. The breadline n.m.r. indicates the onset of a dynamic disorder of the chelate rings upon heating through the phase transition. The weakening of the crystal field may be due to this dynamic disorder and/or the presence of a small tetrahedral distortion. Electrical conductivity measurements show interesting relaxation processes associated with the phase transition.

L. Antolini; L. Menabue; G. C. Pellacani; M. Saladini; M. Sola; L. P. Battaglia; A. Bonamartini Corradi ( 1984 ) - X-ray evidence of intermolecular stacking interactions in a ternary complex. Crystal and molecular structure of the complex bis(N-benzyloxycarbonylglycinato)(2,2'-bipyridine)(propan-2-ol)copper(II) - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume - - pp. da 2319 a 2323 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The title compound crystallyzes in the triclinic space grup P1 with four formula units in a cell of dimensions a = 22.199(11), b = 15.357(6), c = 10.223(4) A, alfa = 103,78(3), beta = 83.06(4) and gamma = 88.89(4). The structure was solved by the heavy-atom method and refined by least-squares calculations to R = 0.095 for 3473 counter data. It consists of two crystallographically independent, but chemically equivalent Cu(bglyO)2(bipy)(PrOH) molecules, which are linked in dimeric units by hydrogen bonding interactions. Each Cu atom shows a slightly distorted square-pyramidal five co-ordination by the bidentate 2,2'-bipyridine ligand and two N-benzyloxycarbonylglycinate ions in the equatorial plane, and by the propan-2-ol molecule in an apical position. The crystal packing is mainly determined by the intermolecular stacking and hydrophobic interactions between the 2,2'-bipyridine molecules and between phenyl groups, respectively. Its pohysical properties are also discussed in the light of its known crystal structure.

L.Antolini; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1983 ) - Coordination behavior of L-aspartic acid: thermal, spectroscopic, magnetic and structural properties of aqua(L-aspartato)(2,2'-bipyridine)copper(II) trihydrate. - INORGANIC CHEMISTRY - n. volume 22 - pp. da 141 a 145 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

[Cu(L-asp)(H2O)(bpy)]x 3H2O crystallizes in the orthorhombic space group P212,21 with four formula units in a cell of dimensionsa = 21.978 (2) A, 6 = 1 1.275 (1) A, and c = 6.841 (1) A. The structure was solved by the heavy-atom method and refinedby least-squares calculations to R = 0.037 for 1640 independent reflections. The structure consists of a monomeric[Cu(L-asp)(bpy)H2O] molecule with three water molecules in the lattice. The geometry around Cu(II) is five-coordinateddistorted square pyramidal. The organic ligands act as bidentate in the basal plane, with a water molecule occupying theapical position. Thermogravimetric analysis shows the complete loss of water molecules in the 335-400 K temperaturerange. Infrared and ligand field spectroscopic results and variable-temperature magnetic measurements are interpretedin the light of the known structure.

L.Menabue; P.Prampolini; M.Saladini; P.Morini ( 1983 ) - Magnetic and spectroscopic behavior of amine adducts of copper(II) N-acetyl -beta-alaninate - INORGANICA CHIMICA ACTA - n. volume 68 - pp. da 157 a 161 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A series of ternary complexes with the general formula Cu(ac-β-ala)2B2·nH2O (ac-β-ala = N-acetyl-β-alaninate ion;n = 0 and B = ethylenediamine (en), 4-methylpyridine (4pic); n = 2 and B = pyridine (py) and 4pic) and Cu(ac-β-ala)2B(B = piperazine (pipz), 2,2′-bipyridine (bipy), py, 3-methylpyridine (3pic), 4pic) were synthesized and investigated by means of infrared, electronic, e.p.r. spectroscopy and variable temperature magnetic measurements. The green monoamine adducts of py, 3- and 4pic (pKa⩽ 6) showed physical properties which indicated a binuclear geometry as in the parent complex [Cu(ac-β-ala)2·H2O]2·2H2O. The |2J| values of these adducts increased with respect to the hydrate complex, and were comparable to those of carboxylic acids of similar complexity. For this type of complexes the narrow spectral range of v(OCO)as and v(OCO)s indicates only slight dependence on N-protected amino acids. The blue or violet monomeric compounds display spectroscopic properties which indicate a tetragonal configuration whose distortion increases with the basic strength of the amine. For en derivatives all the experimental results are in accord with a square geometry with CuN4 chromophore, the amino acid acting only as a counterion.

F. Cariati; G. Ciani; L. Menabue; G. C. Pellacani; G. Rassu; A. Sironi ( 1983 ) - Relation between structures and spectroscopic properties of Group IIB metal [M(chelate)X2] complexes (X = Cl, Br, I). Crystal and molecular structure of [H2NCH2(CH3)2CCH2NH2]MX2 complexes (M = Zn, X = Cl, Br; M = Cd, X = Br) - INORGANIC CHEMISTRY - n. volume 22 - pp. da 1897 a 1902 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The synthesis and structural and spectroscopic characterization of a series of d10 metal(II) compounds of the type [M(dmpd)X2] (M = Zn(II), Cd(II), Hg(II); dmpd = 2,2-dimethylpropane-1,3-diamine; X = Cl, Br, I) are described. The different spectroscopic properties, which divide the complexes into two classes, are discussed and unambiguously assigned only on the basis of the knowledge of the crystal structure of compounds representative of each class. Therefore, the crystal structures of [Zn(dmpd)Cl2] (I), [Zn(dmpd)Br2] (II), and [Cd(dmpd)Br2] (III) are determined from three-dimensional single-crystal X-ray data. The complexes are monoclinic, space groups P21/m for I and II and P21 for III, with two formula units in cells of the following dimensions: a = 6.014 (1) Å, b = 7.724 (1) Å, c = 10.483 (1) Å, and β = 91.32° for I; a = 6.234 (2) Å, b = 7.968 (2) Å, c = 10.628 (2) Å, and β = 91.81° for II; a = 11.288 (2) Å, b = 5.893 (1) Å, c = 7.622(1) Å, and β = 92.72° for III. The structures have been refined to R = 0.024, 0.036, and 0.025 for I, II, and III, respectively. The complexes I and II are isomorphous and isostructural. In these complexes the zinc atom is tetrahedrally surrounded by two halogen and two nitrogen atoms. The only difference between these complexes is the strength of hydrogen-bonding interactions. In the complex III the cadmium atom is octahedrally surrounded by four bromine atoms and two nitrogen atoms of a dmpd molecule. The octahedral moieties are linked in infinite chains by bromine bridges. In all the compounds the dmpd molecule acts as a chelating ligand, giving a six-membered chelate ring in a partially flattened chair conformation.

L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1983 ) - Role of the tosyl group on the coordination ability of N-protected aminoacids. 3. Ternary complexes of copper(II) with N-tosylglycine and aromatic amines. Crystal and molecular structure of bis(N-tosylglycinato) bis(N-methylimidazole)copper(II). - INORGANIC CHEMISTRY - n. volume 22 - pp. da 1902 a 1906 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some compounds of the type Cu(TsglyH)2X2 (TsglyH = N-tosylglycinate anion; X = imidazole, N-methylimidazole, andpyridine) have been prepared and characterized by means of magnetic moments and ESR, electronic, and infrared spectra.For one of them, bis(N-tosylglycinato)bis(N-methylimidazole)copper(II), the crystal structure has also been determined. The complex has square-planar coordination via two centrosymmetriccarboxylic oxygens and two imidazole nitrogens. Two weak interactions (2.758 A) with two carboxylic oxygens completethe coordination to a strongly distorted tetragonal bipyramid. Packing is determined by N-H(amide)-.O(carboxylate)hydrogen bonds and by van der Waals contacts. Electronic, infrared, and ESR spectra are consistent with this type ofstructure for all the complexes.

L.P.Battaglia; A.Bonamartini Corradi; L.Menabue ( 1983 ) - Structure and spectroscopic properties of ternary complexes of copper(II) N-tosylglcinates. Crystal and molecular structure of catena-mu-aqua)bis(N-tosylglycinato)bis(4-metylpyridine) copper(II). A case of linear-chain water bridged copper(II) polymer. - INORGANIC CHEMISTRY - n. volume 22 - pp. da 3251 a 3255 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Two ternary complexes of copper(II)- N-tosylaglycine with pyridine and 4-Methylpyridine were prepared and characterized by means of magnetic, EPR, electronic, and IR spectra. Forone of them, catena-(mu-aqua)bis(N-tosylglycinato)bis(4-methylpyridine)copper(II). The structure was solved by the heavy-atom technique and refined by the full-matrix least-squares method to a final R index of 0.047 for 1965 unique reflections. The copper environment consists of two centrosymmetrically related carboxylic oxygens and two 4-methylpyridine nitrogens in a square-planararrangement. Two centrosymmetric water molecules, lying on the twofold axis, complete the coordination polyhedron totetragonal bipyramid and bridge the copper atoms, forming chains running along the [001] axis. The dependence of thed-d band maximum on the Cu-O(axia1) contact (2.755 (1) A). TheEPR parameters are also consistent with a CuN204 chromophore. The infrared spectra are discussed in comparison withthose of other structurally known copper(I1)-N-tosylglycinate complexes.

ANTOLINI L.; BATTAGLIA L.P.; BATTISTUZZI GAVIOLI G.; BONAMARTINI CORRADI A.; GRANDI G.; MARCOTRIGIANO M.; L. MENABUE; PELLACANI GC. ( 1983 ) - The role of the tosyl group on the coordination ability of N-protected amino acids. 1. Solid-state behaviour of (N-tosylglycinato)copper(II) complexes: crystal and molecular structure of (N-tosylglycinato)triaquacopper(II) and dipotassium Bis(N-tosylglycinato)cuprate(II) complexes - American Chemical Society:1155 Sixteenth Street Northwest:Washington, DC 20036:(800)227-5558, EMAIL: service@acs.org, INTERNET: http://www.pubs.acs.org, Fax: (614)447-3671 ) - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - n. volume 105 - pp. da 4327 a 4332 ISSN: 0002-7863 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The formation of binary complexes of N-tosylglycine and copper is investigated as a function of pH and Metal:ligand molar ratio. The number and type of complex species in solution were determined and their stability constant evaluated.

L.Antolini; L.P.Battaglia; G.Battistuzzi Gavioli; A.Bonamartini Corradi; G.Grandi; G.Marcotrigiano; L.Menabue ; G.C.Pellacani ( 1983 ) - The role of the tosyl group on the coordination ability of N-protected amino acids. 2.Behavior of the copper(II) ion-N-tosylglycinate system in aqueous solution. - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - n. volume 105 - pp. da 4333 a 4337 ISSN: 0002-7863 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The formation reactions of complexes of N-tosylglycine with the copper(I1) ion were investigated by polarographicmeasurements in aqueous solution at different ligand concentrations and pH values to identify the number and type of complexspecies present in aqueous solution, to establish the equilibria in which they are involved, and to calculate their stability constants.A polarographic, pH-metric, and spectrophotometric study of the ligand was also performed to determine its pK, values (3.5and 11.6). Until pH 5 no formation of complexes is observed, above this pH different complexes were identified as a function metal/ligand molar ratio. Simple binary species and hydroxylated complexes were recognized.

L.P.Battaglia; A.Bonamartini Corradi; L.Antolini; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1982 ) - Coordination behavior of L-aspartic acid: ternary nickel(II) complexes with imidazoles. Crystal and molecular structure of (L-aspartate)tris(imidazole)nickel(II). - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - n. volume 104 - pp. da 2407 a 2411 ISSN: 0002-7863 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Two ternary compounds of formula Ni(L-asp)B, (L-asp = L-aspartate ion; B = imidazole and 2-methylimidazole)were prepared and characterized by means of magnetic and spectroscopic measurements. For one of them, the Ni(L-asp)(im),complex, the crystal structure was also determined. The compound crystallizes in the monoclinic space group P2, with fourformula units in a cell of dimensions a = 22.001 (2) A, b = 8.631 (1) A, c = 8.514 (1) b;, and p = 95.07 (1)°. X-ray diffractiondata were collected with a Philips PW 1100 automated four-circle diffractometer by using Mo Ka radiation. The structurewas solved by the heavy-atom method and refined by full-matrix least-squares procedures to a final R factor of 0.0514 for205 1 independent reflections. The structure consists of two crystallographically independent but chemically equivalentNi(L-asp)(im), molecules in which each Ni atom is coordinated in a distorted octahedral geometry by one L-aspartate ion,acting as a tridentate ligand, and by three imidazole molecules. Infrared and ligand field spectroscopies and magnetic measurementsall agree with the observed crystal structure.

L.Antolini; L.Menabue; P.Prampolini; M.Saladini ( 1982 ) - Coordination properties of N-protected amino acids: simple and mixed (N-benzoyl-DL-leucinate)copper(II) complexes. - INORGANICA CHIMICA ACTA - n. volume 66 - pp. da 19 a 23 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

One green compound of the type Cu(BzLeu)2·2H2O and mixed complexes with amines of the type Cu(BzLeu)2·Bn·mH2O (n = 2, m = 0 and B = pyridine, 3- and 4-picoline and morpholine; n = 1, m = 2 and B = 1,10-phenanthroline, 2,2′-bipyridyl and piperazine) were prepared and characterized in the solid state by means oflow- and room-temperature magnetic measurements, room-temperature electronic, infrared and e.p.r. spectra. For the green compound, which displays physical characteristics similar to those of copper(II) acetate monohydrate and similar dimeric complexes, the complicated magnetic properties, discussed in detail, demonstrate the presence of a great amount (∼36%) of mononuclear copper(II) impurities, although the complex is analytically pure. For all the mixed complexes with amines, the physical measurements are consistent with a tetragonally distorted configuration of the copper(II) ion with the presence of a CuO4N2 chromophore. In all the complexes the amino acid coordinates only through the carboxylate group, acting as a ‘simple’ carboxylic acid.

L.Antolini; L.Menabue; P.Prampolini; M.Saladini ( 1982 ) - Magnetic and spectroscopic properties of dimeric copper(II) N-benzoylvalinates. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume not available - pp. da 2109 a 2112 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The complexes cis-[RuVILO2]2+, cis-[RuVLO2]+ and cis-[RuIIL(MeCN)2]2+(L =N,N,N′,N′,3,6-hexamethyl-3,6-diazaoctane-1,8-diamine) have been prepared and their structures determined. The two Ru[double bond, length half m-dash]O bonds in cis-[RuVILO2]2+ are equivalent [1.795(9)Å] and the O–Ru–O angle is 112.0(4)°. In cis-[RuVLO2]+ the two Ru[double bond, length half m-dash]O distances are 1.751(3) and 1.756(4)Å, and the O–Ru–O angle is 115.1(2)°. The N(MeCN)–Ru–N(MeCN) angle in cis-[RuIIL(MeCN)2]2+ is 86.1(2)°. The cyclic voltammogram of cis-[RuVILO2]2+ in acetonitrile exhibits a reversible one-electron RuVI–RuV couple at 0.53 V vs. Ag–AgNO3(0.1 mol dm–3). In aqueous solutions, proton-coupled electron-transfer redox couples are observed. This complex is capable of oxidising a wide variety of organic substrates including 2,3-dimethylbutane and adamantane. Oxidation of saturated alkanes occurred preferentially at the tertiary C–H bond.

F.Cariati; L.Erre; G.Micera; L.Menabue; M.Saladini; P.Prampolini ( 1982 ) - Magnetic investigations on some copper(II) N-acetyl- and N-benzoyl-alaninates. - INORGANICA CHIMICA ACTA - n. volume 53 - pp. da 85 a 89 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The magnetic properties of Cu(Ac-α-ala)2·H2O, Cu(Bz-α-ala)2·H2O and Cu(Bz-β-ala)2 (Ac-α-ala = N-acetyl-DL-alaninate, Bz-α-ala = N-benzoyl-DL-alaninate, Bz-β-ala = N-benzoyl-β-alaninate ion) have been investigated by means of variable-temperature magnetic and ESR measurements. The magnetic behaviour of the compounds suggests binuclear structures with exchange integrals typical of copper acetate monohydrate-like complexes. Low-temperature ESR spectra of the powdered samples show triplet absorptions characteristic of axially symmetric (Cu(Ac-α-ala)2·H2O and Cu(Bz-α-ala2·H2O) or rhombically distorted (Cu(Bz-β-ala)2) copper(II) carboxylate dimers. A polymeric structure is proposed for Cu(Bz-β-ala)2 due to the detection of interdimer exchange between triplet states.

L. P. Battaglia; A. Bonamartini Corradi; G. Marcotrigiano; L. Menabue; G. C. Pellacani ( 1982 ) - N-(2-Ammonioethyl)morpholinium tetrachlorocuprates(II). The first instance of two forms, one green and one yellow, both stable at room temperature - INORGANIC CHEMISTRY - n. volume 21 - pp. da 3919 a 3922 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Crystals of the green form of the title compound are monoclinic, space group I2/a, with a = 15.934 (3) Å, b = 13.023 (1) Å, c = 14.069 (3) Å, ? = 118.89 (1)°, and Z = 8. Crystals of the yellow form are monoclinic, space group P21/a, with a = 15.909 (3) Å, b = 12.420 (3) Å, c = 6.355 (1) Å, ? = 98.77 (5)°, and Z = 4. The crystal structures were determined by three-dimensional X-ray diffraction and refined to R = 0.047 and 0.045 for the green and yellow forms, respectively. In the green crystals two crystallographically independent [CuCl4]2- anions are present, one of them with a flattened-tetrahedral geometry and the other square planar for symmetry requirements. In the yellow form only [CuCl4]2- distorted-tetrahedral ions are present. In both modifications, the anions form hydrogen bonds with the N-(2-ammonioethyl)morpholinium cation, with stronger bonds being present in the green modification. The spectroscopic and magnetic properties of the complexes are explained in the light of their known crystal structures

L.Antolini; L.Menabue; G.C.Pellacani; G.Marcotrigiano ( 1982 ) - Structural, spectroscopic and magnetic properties of diaqua(L-aspartato)nickel(II) hydrate. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 2541 a 2543 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal structure of the title compound was determined by X-ray analysis. The compound crystallizes in the orthorhombic space group P212121 with cell dimensions a = 12.306(2), b = 8.996(2), c = 7.596(1) Å, and Z = 4. The structure was solved by the heavy-atom method and refined by least-squares calculations to a final R value of 0.034. The compound is isostructural with the corresponding zinc(II) salt. The structure consists of polymeric linear chains in which the Ni atom is co-ordinated in a distorted octahedral manner by one aspartate ion, acting as a tridentate ligand, by two water molecules, and by one β-carboxylate O atom of a second aspartate ion. Magnetic and spectroscopic results are also discussed.

L. Menabue; G.C. Pellacani; A. Albinati; F. Ganazzoli; F. Cariati; G. Rassu ( 1982 ) - Synthesis and low-frequency vibrational spectra of N-(2-ammoniumethyl)- piperazinium halide-mercurates(II). Crystal structure of N-(ammomoniumethyl)- piperazinium monochloride tetrachloromercurate(II) - INORGANICA CHIMICA ACTA - n. volume 58 - pp. da 227 a 231 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Compounds of the type [N(2amet)pipzH3)-[HgX4]X (N(2amet)pipzH3 = N-(2-ammoniumethyl)-piperazinium trication; X = Cl, Br) have been prepared and characterized by means of Raman and far-IR spectroscopy. The crystal determination of [N(2amet)pipzH3)-[HgCl4] Cl shows that it is composed of discrete monomeric [HgCl4]2− units, chloride and [N(2amet)pipzH3]3+ ions. Co-ordination around the mercury atom is distorted tetrahedron with two shorter and two longer HgCl distances (av. 2440(9) and av. 2.556(9) Å, respectively).

L.Antolini; L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano; L.Menabue; G.C.Pellacani; M.Saladini ( 1982 ) - Synthesis and spectroscopic and magnetic properties of mixed-ligand complexes of copper(II) with imidazole and N-protected amino acids. Crystal and molecular structure of bis(hippurato) bis(imidazole)copper(II) . - INORGANIC CHEMISTRY - n. volume 21 - pp. da 1391 a 1395 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Mixed-ligand complexes of the type CuL2(IM)2 (L= N-protected aminoacidate= benzoylglycinate (hippurate), acetylglycinate (aceturate), N-acetyl and N-Benzoyl-DL- alaninate etc...were synthesized and characterized by means of electronic, infrared and EPR spectroscopy. For bis(hippurato)bis(imidazole)copper(II) the crystal structure was also determined.

L.P.Battaglia; A.Bonamartini Corradi; L.Menabue; G.C.Pellacani; M.Saladini; P.Prampolini ( 1982 ) - Ternary complexes of copper(II) with N-protected amino acids and N-methylimidazole. Crystal and molecular structure ofbis(N-acetyl-alaninato) bis(N-methylimidazole)copper(II) dihydrate. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume not available - pp. da 781 a 785 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Ternary complexes of the type [CuL2(mim)2][L =N-acetyl-α-, N-benzoyl-α-, N-acetyl-β-, or N-benzoyl-β-alaninate(1–); mim =N-methylimidazole], [CuL2(mim)2]·H2O (L = benzoylglycinate, N-acetyl- or N-benzoyl-DL-leucinate), and [CuL2(mim)2]·2H2O (L =N-acetyl-α-alaninate) have been synthesized, and characterized by electronic, i.r., and e.s.r. spectroscopy. The crystal structure of the title complex has also been determined by single-crystal X-ray diffraction. The compound crystallizes in the triclinic space group P[1 with combining macron] with one molecule in a unit cell of dimensions a= 7.666(1), b= 8.430(1), c= 9.955(1)Å, α= 106.33(1), β= 86.27(1), and γ= 109.34(1)°. Least-squares refinement of the 215 variables gave a value of R 0.056 for 1 822 independent reflections having Fo > 4σ(Fo). The square-planar structure consists of a copper atom lying on the centre of symmetry surrounded by two carboxylic oxygen and two N-methylimidazole nitrogen atoms. Electronic and e.s.r. spectroscopic data are consistent with this type of structure (CuO2N2 chromophore) for the hydrated complexes and with a tetragonally elongated octahedral stereochemistry (CuO4N2 chromophore) for the anhydrous complexes. It is suggested that the amino-acid acts as an ‘ asymmetric ’ bidentate ligand in the latter complexes.

L.Antolini; L.Menabue; G.C.Pellacani; M.Saladini; G.Marcotrigiano ( 1982 ) - The effect of hydrogen bonding on the chlorocuprate(II) geometry. A compound containing an unusual copper(II)/chlorine ratio of 1:6. Crystal and molecular structure of bis(Nbenzylpiperaziniumchloride) tetrachloro cuprate(II). - INORGANICA CHIMICA ACTA - n. volume 58 - pp. da 193 a 200 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A compound of the type (NBzpipzH2)2CuCl6 (NBzpipzH2)2 = N-benzylpiperazinium dication) was prepared and characterized by means of X-ray, electronic, differential scanning calorimetric and magnetic measurements. Crystal of the compound are monoclinic, space group Pc with a = 21.954(2) Å, b = 7.0889(5) Å, c = 9.1391(9) Å, β = 97.054(8)°, and Z = 2. Intensities were obtained from 0–20 scan with a Philips PW 1100 automatic four-circle diffractometer using graphite-monochromated Mo Kα radiation. The structure was solved by conventional heavy-atom methods, and least-squares refinement of structural parameters led to a conventional R factor of 0.049 for 1508 reflection having I > 3σ(I). The crystal consists of a CuCl2−4 anion, two lattice Cl− ions, and two (NBzpipzH2)2+ cations. The CuCl2−4 ion shows a slight tetrahedral distortion superimposed to the basic square-planar geometry, but may be also regarded as an example of an extremely flattened tetrahedron. The strong hydrogen bonds formed by the N-bonded H atoms of the cations, which bridge the CuCl2−4 anions and link the Cl− ions, were considered responsible for the unusual geometry of the CuCl2−4 chromophore. The electronic spectra are discussed and assigned on the basis of the known crystal structure.

L.Antolini; G.Marcotrigiano; L.Menabue; G.C.Pellacani; M.Saladini ( 1982 ) - Thermal, spectroscopic, magnetic and structural properties of mixed-ligand complexes of copper(II) with L-aspartic acid and amines. Crystal and molecular structure of (L-aspartato) (imidazole)copper(II) dihydrate - INORGANIC CHEMISTRY - n. volume 21 - pp. da 2263 a 2267 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A blue compound of the type Cu(L-Asp)2H2O and Cu(L-Asp)(B)2H2O were prepared and characterized by means of thermal, spectroscopic and magnetic measurements. For the compound with B= imidazole the crystal structure is also reported.

L.Antolini; L.Menabue; M.Saladini; P.Morini ( 1981 ) - Amino acids as cations: tetrachlorocuprates(II) of glycine and b-alanine cations. - INORGANIC AND NUCLEAR CHEMISTRY LETTERS - n. volume 17 - pp. da 41 a 43 ISSN: 0020-1650 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The effect of glycine and β-alanine, when act as counterions, on the coordination geometry of the tetrachlorocuprates has been investigated.

R.Battini; G.Battistuzzi Gavioli; G.Grandi; L.Menabue; G.C.Pellacani; M.Saladini; A.Bonamartini Corradi ( 1981 ) - Co-ordination properties of N-protected amino acids. Solution and solid state behavior of bis(benzyloxycarbonyl-L-tryptophanato)nickel(II) and its mixed complexes - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume not available - pp. da 1665 a 1668 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Polarographic measurements show that nickel(II) ion and benzyloxycarbonyl-L-tryptophan (Z-L-tryptophan) form complexes in methanol with 1 : 2 and 1 : 4 metal-to-ligand ratios, depending on the ligand concentration. A complete scheme of the reactions which take place in solution and at the electrode is proposed. The 1 : 2 complex [NiL2]·2H2O and some amine adducts have been obtained in the solid state. In the solids the amino-acid is co-ordinated only through the carboxylate group.

L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1981 ) - Copper(II) complexes of N-protected amino acids: synthesis and spectroscopic, magnetic and structural, properties of bis(N-acetyl-beta-alaninato)diaquacopper(II) dihydrate and tetrakis[-(N-acetyl-beta-alaninato] diaquadicopper(II) dihydrate. A case of structural isomerism. - INORGANIC CHEMISTRY - n. volume 20 - pp. da 1075 a 1080 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A blue and a green compound of the type Cu(Ac-beta-ala)2 x2H20 and a green compound of the type [Cu(Ac-beta-ala)2] were prepared and characterized by means of room-temperature electronic and infrared spectroscopy, low- and room-temperature magnetic and EPR measurements and DSC analysis. For the blue and green hydrate compounds the crystal structure was also determined by single-crystal X-ray diffraction methods. In the blue compound the copper environment consists of two centrosymmetrically related carboxylic oxygens and two water molecules in asquare-planar arrangement. Two weak interactions involving the uncoordinated carboxylic oxygen atoms complete thecoordination to a severely distorted tetragonal bipyramid. In the green isomeric compound the structureconsists of centrosymmetric dimeric units. Coordination around each metal atom is elongated octahedrally with the carboxyloxygen atoms at the equatorial sites and a water molecule and a copper atom in the axial positions. The importance ofhydrogen bonding in the packing of the molecules is also discussed. These complexes represent an example of structuralisomerism depending on the influence of the solution media. The spectroscopic and magnetic properties are interpretedon the basis of the crystal structures, in particular the hydrate and anhydrous green compounds, show antiferromagnetic properties.

F.Cariati; A.Panzanelli; L.Antolini; L.Menabue; G.C.Pellacani; G.Marcotrigiano ( 1981 ) - Low-frequency vibrational spectra of some 4-benzylpiperidinium and N-benzylpiperazinium pentahalogenoantimonates(III) and pentahalogeno bismuthates(III). Partial crystal structure determination of 4-benzylpiperidinium pentachloroantimonate(III). - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 909 a 913 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some compounds of the type [bzpipn]2[MX5] and [bzpipzn][MX5](bzpipn = 4-benzylpiperidinium cation; bzpipzn =N-benzylpiperazinium dication; M = Sb or Bi; X = Cl or Br) have been prepared and characterized by means of Raman and far-i.r. spectroscopy. The crystal data, although poor, of the [bzpipn]2[SbCl5] compound show that the antimony atom is surrounded by six chlorine atoms. Five of these are strictly bonded to the metal atom (2.5 Å), forming a square-pyramidal SbCl52– unit, and another chlorine atom of an adjacent SbCl52– unit completes the octahedral co-ordination around the metal atom through a weak interaction (3.2 Å), giving rise to infinite chains running along the c axis. The molecular structures of the complexes depend more on the halogen atoms than on the counter-cation dimensions and hydrogen-bonding abilities. In fact the vibrational spectra of all the chloro-anions may be interpreted on the basis of the crystal structure of the [bzpipn]2[SbCl5] compound, while those of the bromo-anions suggest the presence of a distorted octahedron of bromine atoms around the metal with two bromine bridges that link adjacent metal atoms.

L.Antolini; L.Menabue; G.C.Pellacani; M.Saladini; G.Marcotrigiano; W.Porzio ( 1981 ) - Spectroscopic and structural investigation of two N-benzylpiperazinium tetrachlorocuprates(II), one hemihydrate and one anhydrous: two compounds containing unequally flattened [CuCI4]2-- tetrahedra. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume not available - pp. da 1753 a 1759 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Polarographic measurements show that nickel(II) ion and benzyloxycarbonyl-L-tryptophan (Z-L-tryptophan) form complexes in methanol with 1 : 2 and 1 : 4 metal-to-ligand ratios, depending on the ligand concentration. A complete scheme of the reactions which take place in solution and at the electrode is proposed. The 1 : 2 complex [NiL2]·2H2O and some amine adducts have been obtained in the solid state. In the solids the amino-acid is co-ordinated only through the carboxylate group.

L.Antolini; L.Menabue ( 1981 ) - Synthesis and spectroscopic properties of some thermochromic copper(II) complexes of N-(2-aminoethyl) heterocyclic derivatives. - TRANSITION METAL CHEMISTRY - n. volume 6 - pp. da 377 a 379 ISSN: 0340-4285 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some copper(II) complexes with heterocyclic amine were prepared and characterized by means of spectroscopic and magnetic measurements.

L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1981 ) - Synthesis, spectroscopic and structural properties of 2,2-dimethyl-propane-1,3-diamine copper(II) complexes. Temperature dependent tetragonal distortion in some thermochromic complexes. Crystal and molecular structure of bis(2,2-dimethylpropane-1,3-diamine)-diperchloratecopper(II). J.Chem.Soc.Dalton Trans., 8-12 (1981) - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 8 a 12 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some compounds of the type [Cu(dmpd)2X2](dmpd = 2,2-dimethylpropane-1,3-diamine and X = Cl, Br, or ClO4) have been prepared and characterized by means of magnetic moments, e.s.r., electronic, and i.r. spectra. For one of them, bis(2,2-dimethylpropane-1,3-diamine) diperchloratocopper(II), the crystal structure has been determined by three-dimensional X-ray diffraction. Crystals are monoclinic, space group P21/c, with unit-cell dimensions: a= 9.724(2), b= 6.287(1), c= 16.191(3)Å, β= 97.66(1)°, and Z= 2. The structure has been refined to R= 0.036 8. Co-ordination around the copper is distorted tetragonal bipyramidal; two centrosymmetric chelate ligands form the base [Cu–N(1) 2.028(3), Cu–N(2) 2.021 (3)Å], and the two centrosymmetric unidentate perchlorate ions form the apices [Cu–O(1) 2.602(3)Å]. The electronic and i.r. spectra of the [Cu-(dmpd)2X2] complexes are temperature-dependent suggesting reversible continuous thermochromism arising through a temperature-dependent axial interaction between the anion and the CuN4 plane, with a more square form being favoured at higher temperature. Other complexes of the types [Cu(dmpd)X2] and [Cu(H2dmpd)X4](X = Cl or Br) were also prepared and investigated and their possible stereochemistries discussed.

R.Andreoli; G.Battistuzzi Gavioli; L.Benedetti; G.Grandi; G.Marcotrigiano;L.Menabue; G.C.Pellacani ( 1980 ) - Complex formation of zinc(II) ion with glycine, N-acetyl- and N-benzoyl-glycine in aqueous and ethanolic solution by polarographic method. - INORGANICA CHIMICA ACTA - n. volume 46 - pp. da 215 a 219 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The complex formation reactions of glycine, N-acetyl- and N-benzoyl-glycine with the Zn(II) ion were investigated using the polarographic method in aqueous and ethanolic solution to identify the number and type of complex species present in solution and to calculate their stability constants. In aqueous basic solution (pH 6–9), only the glycinate anion reacts with the metal ion forming three complexes of the type ZnL+, ZnL2 and ZnL−3. On the contrary in ethanolic solution all three amino acids react; the N-protected amino acid anions form four complexes of the type ZnL+, ZnL2, ZnL−3 and ZnL2−4, while in the presence of the glycine anion two complexes only of the type ZnL+ and ZnL2 were identified. The results obtained for these systems in aqueous and ethanolic solution, discussed in comparison with those of the corresponding cadmium(II) systems, also suggest an amino acid coordination to the metal ion through different coordination sites in the solvents examined.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1980 ) - (N-acetyl-DL-valinate)copper(II) complexes: effect of amines on the amino acid coordination. - INORGANICA CHIMICA ACTA - n. volume 46 - pp. da 107 a 112 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Two compounds, Cu(AcVal)2 and Cu(AcVal)2 · H2O, and their amine adducts, Cu(AcVal)2Bn(AcVal = N-acetyl-DL-valinate ion; n = 1 and B = 1,10-phenanthroline, 2,2′-bipyridyl and piperazine; n = 2 and B = pyridine, 3- and 4-methylpyridine, pyridazine N-methylpiperazine, morpholine and piperidine) were prepared and investigated by means of room temperature infrared, electronic and e.p.r. spectroscopy and low and room temperature magnetic susceptibilities. The results suggest a tetragonal configuration for the Cu(AcVal)2, with CuO4 chromophore, and for the amine adducts, with essentially CuO2N2 chromophore, and a binuclear configuration for the Cu(AcVal)2 · H2O, which shows an exchange integral (-2J) of 351 ± 9 cm-1 and a zero field splitting D of 0.39 cm-1 which are in the range found for the copper acetate monohydrate complex and other similar complexes. The amino acid coordinates by the carboxylate group in all the complexes

A.Albinati; S.V.Meille; F.Cariati; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1980 ) - Preparation, crystal structure and vibrational spectra of N-benzylpiperazinium pentachlorodimercury(II) complexes: (NbzpipzH)Hg X (X=Cl,Br) - INORGANICA CHIMICA ACTA - n. volume 38 - pp. da 221 a 226 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The preparation of new mercury(II) compounds, (NbzpipzH)Hg2X5 (NbzpipzH = N-benzylpiperazinium monocation; X = Cl, Br) is reported. The determination of the structure of (NbzpipzH)Hg2Cl5 by three-dimensional single-crystal X-ray analysis is described. The structure contains two different mercury atoms. One of them binds covalently two chlorine atoms and two bridged chlorine atoms with long contacts. The coordination around the other mercury is tetrahedrically distorted and involves one terminal and two bridged chlorine atoms and one molecule of N-benzylpiperazinium monocation. Far-infrared and Raman spectra are interpreted on the grounds of the crystal structure of compounds suggesting a relation between the values of a mercury-halogen stretching frequencies and the related bond distances.

L.Antolini; L.Menabue; M.Saladini; P.Morini ( 1980 ) - Silver(I) complexes with N-protected amino acids. - INORGANICA CHIMICA ACTA - n. volume 46 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Silver complexes with N-protected amino acids are synthesized and characterized by means of IR spectroscopy

L.Antolini; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1980 ) - Spectroscopic and structural investigation on the pentachloro- and (mixedpentahalo) cuprates(II) of the N-(2-ammoniumethyl)piperazinium cation. The first case of monomeric entahalocuprate(II) having square-pyramidal structure. Crystal and molecular structure of the (N-(2-ammoniumethyl)piperazinium) pentachlorocuprate(II) dihydrate. - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - n. volume 102 - pp. da 1303 a 1309 ISSN: 0002-7863 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Pentahalo- and mixed penta-halocuprates(II) with N-alkyl derivatives of piperazine were synthesized and charaterized by means of electronic and infrared spectra. The crystal structure of pentachloro complex was determined. The structure consists of discrete [CuCl5]3- anions with slightly distorted square-pyramidal geometry.

L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1980 ) - Spectroscopic and structural investigation on the trihalocuprates(II) of the 4-benzylpiperidinium cation. Crystal and molecular structure of the bis(4-benzylpiperidinium)hexachlorodicuprate(II). - INORGANIC CHEMISTRY - n. volume 19 - pp. da 125 a 129 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some copper(II) complexes of halide derivatives of 4-benzylpiperidinium have been synthesized and characterized by means of electronic and far-infrared spectra. The crystal structure of bis(4-benzylpiperidinium)hexachlorodicuprate(II) has been determined, and contains [Cu2Cl6]2- units joined by means of weak intermolecular Cu-Cl interactions.

L.Antolini; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1980 ) - Synthesis and spectroscopic and structural investigation on tetrakis(N-(2-ammonioethyl)- piperazinium)di-mu-chloro-dodecachlorocuprate(II) bis(tetrachlorocuprate(II)), (C6H18 N3) Cu5Cl22 . J.Am.Chem.Soc., 102, 5506-5510 (1980). - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - n. volume 102 - pp. da 5506 a 5510 ISSN: 0002-7863 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A red compound of the type [N(2amet)pipzH3]4Cu5Cl22 (N(2amet)pipzH3 = N-(2-ammonioethyl)piperazinium cation) was prepared and investigated by means of X-ray structural analysis, magnetic moment, and electronic and infrared spectroscopy. The substance crystallizes with four formula units in space group Ibam of the orthorhombic system in a cell of dimensions a = 16.697 (5) Å, b = 14.479 (3) Å, c = 23.757 (7) Å, and V = 5743.4 Å3 at 21°C. X-ray diffraction data were collected with a Philips PW 1100 automatic four-circle diffractometer, using Mo K? radiation. The structure was solved by direct methods; least-squares refinement of structural parameters led to a conventional R factor of 0.032 for 1246 independent reflections [I > 3.0?(I)]. The unit cell contains a Cu3Cl14 8- anion found for the first time, two unequally flattened CuCl4 2- tetrahedra, and [N(2amet)pipzH3]3+ trications, which are hydrogen bonded to anions. The central Cu atom of the centrosymmetric Cu3Cl14 8- ion has a tetragonally elongated octahedral six coordination, while the terminal Cu atoms have a distorted square-pyramidal pentacoordination; the coordination polyhedra share their axial Cl atoms. The contribution of hydrogen bonding to coordination geometry about the copper atoms is discussed. Its magnetic moment and electronic and infrared spectra are also interpreted on the basis of the known crystal structure.

L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1980 ) - Synthesis, spectroscopic and structural properties of bis (N-acetyl-DL-tryptophanato)copper(II) complex and its amine adducts: effect of amines on the amino acid coordination. Crystal and molecular structure of diaqua bis(N-acetyl-DL-tryptophanato)bis(pyridine)copper(II). - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - n. volume 102 - pp. da 2663 a 2669 ISSN: 0002-7863 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A green compound of the type Cu(Ac t rp)xH2O( ctrp = N-acetyl-DL-tryptophanate ion) and its aromatic and aliphaticheterocyclic amine adducts, Cu(Actrp)2B2 (B = pyridine (py), 3- and 4-methylpyridine (3- and 4-pic), N-methylpiperazine(NCHjpipz), morpholine (morph), and piperidine (pipd)), Cu(Actrp)2(py)2(H20)2, and Cu(Actrp)2.pipz (pipz = piperazine),were prepared and characterized by means of low- and room-temperature magnetic and EPR measurements androom-temperature electronic and infrared spectroscopy. While Cu(Actrp)2 xH2O shows physical properties indicating a binuclearconfiguration, all the aromatic heterocyclic amine adducts appear to possess a tetragonal configuration with CUOJN~chromophore. For one of the latter complexes, diaquabis(N-acetyl-DL-tryptophanato)bis(pyridine)copper(Il), the crystalstructure was also determined by single-crystal X-ray diffraction methods. The complex crystallizes in the monoclinic spacegroup P21/c with two molecules in a unit cell of dimensions a = 9.377 (6) A, b = 19.341 (14) A, c = 11.615 (7) beta = 123.2(2)°, .The geometry about the copper atom,which is coordinated to two carboxylic oxygens and two pyridine nitrogen atoms. is completed to an elongated tetragonal bipyramidby two weak interactions with two water molecules. The Cu-N, Cu-O(amino acid), and Cu-O(water) distances are 1.95(l), 2.02 ( I ) , and 2.61 (1) A, respectively, and the O(amino acid)-Cu-N angle is 87.9 (6)’. For the adducts of the aliphaticheterocyclic amines a square-planar geometry with CuO2N2 chromophore may be suggested. In all the complexes reportedin this work the amino acid appears to coordinate the copper(II) ion only toward the carboxylate group. For the assignmentof the way in which the carboxylate group coordinates, we suggest that the observation of the position of the v(OCO), is particularlyrelevant

G.Marcotrigiano; L.Menabue; P.Morini; G.C.Pellacani ( 1979 ) - Bis(N-acetyl-DL-leucinate)copper(II) complexes and their amine adducts. - BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN - n. volume 52 - pp. da 3420 a 3423 ISSN: 0009-2673 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A compound of the type Cu(AcLeu)2 and its amine adducts of the type Cu(AcLeu)2Bn (AcLeu=N-acetyl-DL-leucinato ion; n=2 and B=pyridine, 3- and 4-methylpyridine, N-methylpiperazine, morpholine, and piperidine; n=1 and B=1,10-phenanthroline, 2,2′-bipyridyl, piperazine, and pyridazine) were prepared and investigated by means of electronic, infrared and EPR spectroscopy and magnetic moment measurements. The results suggest a tetragonal configuration for the Cu(AcLeu)2 complex and the amine adducts with CuO4 and CuO2N2 chromophores, respectively. For the green Cu(AcLeu)2·pid complex a binuclear configuration similar to that observed for the bis(acetato)copper(II) monohydrate complex is suggested. The amino acid in all the complexes is found to coordinate toward the carboxylato group. In the assignment of the way in which the carboxylato group coordinates, in addition to the difference between their antisymmetric and symmetric stretching frequencies, we also pay special attention to the position of the symmetric stretch, which is directly connected with the oxygen atom linked to the metal ion.

G.Marcotrigiano; L.Menabue; G.C.Pellacani; M.Saladini ( 1979 ) - Cobalt(II), nickel(II) and zinc(II) complexes of peptide group containing amino acids Bis(acetyl-DL-valinate)metal(II) complexes - INORGANICA CHIMICA ACTA - n. volume 32 - pp. da 149 a 155 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

First row transition metal(II) complexes of N- acetyl-DL-valine of the type M(AcVal)2·xH2O (M = Co(II), Ni(II) and x = 2; M = Zn(II) and X = O) and their amine adducts of the type M(AcVal)2B2 xH2O (M = Co(II), Ni(II) and Zn(II); B = pyridine, 3- and 4-methylpyridine, 1,10-phenthroline) were prepared and investigated by means of magnetic measurements, electronic, infrared and 1H n.m.r. spectroscopy. Magnetic moments and electronic spectra of the Co(II) and Ni(II) compounds, consistent with hexacoordinated metal(II) with some distortion from the Oh symmetry, suggest the presence of MO6 and MO4N2 chromophores for the hydrate and base adducts, respectively. By comparing the Dq values of the present complexes and those of the other N-substituted arnino acids previously studied, a spectrochemical series of the amino acid ligands is constructed. Also the infrared spectra agree with the coordination of the amino acid toward the carboxyl group. The trans-effect of the amines, with respect to that of the water, results in a weakening of the N-acetyl-DL-valinate coordination strength in the order py > 4pic > 3pic, as steric effects prevail over the inductive effects. The solution electronic and infrared spectra, which are very similar to those of the solid compounds, and the 1H n.m.r. spectra of the diamagnetic zinc(II) complexes indicate that the same complexes also exist in solution. The coupling of the CHNH group in the 1H n.m.r. spectra and the shift of the ν(NH) and δ(NH) vibrations in the infrared spec- tra of the solution, with respect to the solid com- plexes, indicate that the hydrogen bonding of the NH group present in the solid complexes it removed in chloroform solution.

L.P.Battaglia; A.Bonamartini Corradi; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1979 ) - Halocuprates(II) of the N-phenylpiperazinium mono- and dications: crystal and molecular structure of N-phenylpiperazinum tetrachlorocuprate(II). Correlation of the electronic spectrum vs. distortion of the CuCl42- anions from tetrahedral symmetry. - INORGANIC CHEMISTRY - n. volume 18 - pp. da 148 a 152 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The X-ray structure of N-phenylpiperazinium tetrachlorocuprate(II), (C10H16N2)CuCl4, was determined by X-ray diffraction methods. Crystals are orthorhombic, P212121, with a = 17.698 (2) Å, b = 8.615 (1) Å, c = 9.841 (1) Å, and Z = 4. A final R value of 4.3 was obtained. The structure consists of [CuCl4]2- anions and N-phenylpiperazinium diprotonated cations. The [CuCl4]2- anions show a flattened tetrahedral geometry, the two larger Cl-Cu-Cl angles being 141.1 and 143.0°; the dihedral angle is 51.6°. The Cu-Cl distances range from 2.23 to 2.27 Å. All four chlorine atoms are involved in Cl?N interactions, which may be responsible for the large distortion of the [CuCl4]2- ion from the tetrahedral configuration. The N-phenylpiperazinium dication shows the usual "chair" configuration. The spectroscopic and magnetic results of the [CuCl4]2- and [CuCl3Br]2- anions are in agreement with a high distortion of these ions from tetrahedral symmetry. A study of the d-d transition maximum vs. the distortion of the CuCl4 chromophore from the Td symmetry is also reported. Some compounds containing the monoprotonated amine such as (NPhpipzH)2Cu2X6 (X = Cl, Br) and (NPhpipzH)2Cu2Cl2Br4 are also studied. Their spectroscopic data suggest the presence of dimeric species in them with highly distorted tetrahedral symmetry

L.Antolini; G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1979 ) - Hydrogen bonding and size effects of the cations on the coordination geometry of the metal ions. Tetrahalocobaltates(II) of the N-ethyl-, 2-ethyl- and 4-benzyl-piperidine cations. Crystal and molecular structure of the bis(4-benzylpiperidinium) tetrachlorocobaltate(II). - INORGANIC CHEMISTRY - n. volume 18 - pp. da 2652 a 2658 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some compounds of formula (LH)2(CoX4), where LH= N-ethyl-, 2-ethyl- and 4-benzylpiperidinium cation were synthesized and characterized by means of spectroscopic (UV-vis and vibratiional spectra), and magnetic measurements. For the chlorocobaltate complex with 4-benzylpiperidinium the crystal structure was determined. The far-IR spectra were discussed on the basis of C2 symmetry

G.Marcotrigiano; L.Menabue; P.Morini; G.C.Pellacani ( 1979 ) - N-acetyl-DL-leucinate cobalt(II), nickel(II) and zinc(II) complexes. - TRANSITION METAL CHEMISTRY - n. volume 4 - pp. da 119 a 122 ISSN: 0340-4285 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Complexes of the type M(AcLeu)2 · B2 (M = CoII, NiII or ZnII; B = H2O, py, 3-pic, 4-pic; AcLeu =N-acetyl-DL-leucinate ion) and M(AcLeu)2 B (M = CoII or ZnII and B = o-phen) were prepared and investigated by means of magnetic and spectroscopic measurements. The i.r. spectra of all the complexes are consistent with bidentate coordination of the amino acid to the metal ion. The room temperature solid state electronic spectra indicate that the symmetry of this species is closer to D4 h and that MO6 and MO4N2 chromophores are present in the M(AcLeu)2 · 2 H2O and M(AcLeu)2Bn · x H2O (B = py, 3-pic, 4-pic, n=2 and x=0 for M = NiII; B = o-phen, n=1 and x=0 for M = CoII; B = py, 3-pic, 4-pic, n=1 and x=1 for M = CoII) complexes, respectively. By comparing the Dq values of the amino acid and those of other N-substituted amino acids previously studied, a spectrochemical series of the the cobalt(II) and nickel(II) complexes is proposed. The1 H n.m.r. spectra of the zinc(II) complexes confirm the proposed stereochemistry.

G.Marcotrigiano; L.Antolini; L.Menabue; G.C.Pellacani ( 1979 ) - N-acetyl-DL-tryptophanatometal(II) (Co(II), Ni(II) and Zn(II)) complexes and their amine adducts. - INORGANICA CHIMICA ACTA - n. volume 35 - pp. da 177 a 181 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

First row transition metal(II) complexes of N-acetyl-DL-tryptophan of the type M(Actrp)2·xH2O (M = Co(II), Zn(II) and x = 2; M = Ni(II) and x = 3; Actrp = N-acetyl-DL-tryptophanato ion) and their amine adducts of the type M(Actrp)2B2 (B = py, 3-pic and 4-pic) were prepared and investigated by means of magnetic measurements, electronic and infrared spectroscopy. The diamagnetic zinc(II) complexes were also investigated in solution by means of 1H n.m.r. spectroscopy. All the experimental results on solid complexes suggest that the carboxylate is coordinated to the metal atom. The effect of the amines in axial position results in a weakening of the strength of the amino acid in-plane coordination. 1H n.m.r. spectra of the diamagnetic zinc(II) complexes indicate that the same type of amino acid coordination also exists in solution.

G.Marcotrigiano; L.Menabue; G.C.Pellacani; M.Tonelli ( 1979 ) - Solid state vibrational spectroscopy of tin(IV), antimony(III) and bismuth(III) halide of N-ethylmorpholinium cation. - SPECTROCHIMICA ACTA. PART A, MOLECULAR SPECTROSCOPY - n. volume 35A - pp. da 871 a 873 ISSN: 0584-8539 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some compounds of the type (LH)2SnX6, (LH)2SbX5 (X Cl, Br), (LH)3Bi2X9 (X Cl, Br, I) and LHSbI4 (LH N-ethylmorpholinium cation) were prepared and characterized by means of the Raman and far i.r. spectroscopy. The vibrational spectra are indicative of an octahedral configuration for the hexahalostannates(IV) and a square-pyramidal configuration for the pentahaloantimonates (III). The (LH)3Bi2X9 complexes may be interpreted on the basis of a D3h, symmetry. The hydrogen bonding ability of the counter cation seems to influence only the coordination geometry of the pentahaloantimonates (III).

G.Marcotrigiano; L.Menabue; M.Saladini; G.C.Pellacani ( 1979 ) - Spectroscopic investigation on the tetrahalo- and mixed-tetrahalocuprates of the N-methyl-piperidinium and N,N'-dimethylpiperazinium cations - INORGANICA CHIMICA ACTA - n. volume 34 - pp. da 43 a 47 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some tetrahalo- and mixed-tetrahalocuprates of the type(LH)2CuClmBr4-m and (LH2)CuCImBr4-m (m = 4, 3, 2, 1, 0; LH = N-methylpiperidinium cation; LH2 =N,N′-dimethylpiperazinium dication) were prepared and investigated by means of spectroscopic (u.v., vis, near i.r., far-i.r.), magnetic and e.p.r. measurements.The results indicate for all the complexes a distorted tetrahedral configuration, the complexes of the N,N′-dimethylpiperazinium dication being more distorted than those of the N-methytpiperidinium cation. A seriesbased on the hydrogen bonding ability of the counter cation, which takes into account counter cations as morpholinium, piperidinium and piperaziniumand some of their deriratives is also proposed.

G.Marcotrigiano; L.Menabue; G.c.Pellacani ( 1979 ) - Tetrahalo and (mixed-tetrahalo)cuprates of the 1-methyl- and 2-methyl.pyperazinium dications. Hydrogen bonding effects on the coordination geometry of the CuX4 2- anions. - JOURNAL OF COORDINATION CHEMISTRY - n. volume 9 - pp. da 141 a 149 ISSN: 0095-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some halo- and (mixed-halo) cuprates of the type (n-MepipzH2)CuXmY4-m (X=Cl; Y=Br; m=4,3,2,1,0; n=1 and 1-MepipzH2=1-methylpiperazinium dication; n=2 and 2-MepipzH2=2-methylpiperazinium dication) and (1-MepipzH·HX)2CuX4 (X=Cl,Br) (1-MepipzH·HX=1-methylpiperazinium monocation hydrohalide) were prepared and characterized by means of spectroscopic, magnetic, differential scanning calorimetric analysis and conductometric measurements. The compounds in the solid state may be divided in two categories: a) the (1-MepipzH2)CuXmY4-m (m=4,3,2,1,0) and (2-MepipzH2)CuXmY4-m (m=1,0) complexes, for which a distorted tetrahedral configuration is suggested from their room-temperature spectroscopic properties; b) the (2-MepipzH2)-CuXmY4-m (m=4,3,2) and (1-MepipzH·HX)2CuX4 complexes, for which an approximately square-planar geometry may be suggested. In particular the (1-MepipzH·HBr)2CuBr4 compound shows a thermochromic behaviour associable with a change in the coordination geometry like all the complexes in N,N′-dimethylformamide solution. The distortion from tetrahedral symmetry of the complexes is discussed on the basis of extensive N-H … X hydrogen bonding interactions, which are proposed as responsible for the planar geometry.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1978 ) - An IR study (4000-250 cm-1) on the complexes of the group IIB metals with N-acetyl-L-, alfa-N-benzoyl-DL- and benzoyl-beta-alanine. - JOURNAL OF INORGANIC & NUCLEAR CHEMISTRY - n. volume 40 - pp. da 753 a 756 ISSN: 0022-1902 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this work the complexing ability of some N-substitutedamino acids toward the Group II B metal ions is investigated. The coordination mode of the ligands were studied by means of infrared spectra.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1978 ) - Electronic, infrared and far-infrared study on the pseudotetrahedral cobalt(II). - INORGANICA CHIMICA ACTA - n. volume 25 - pp. da 57 a 62 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some complexes of the type CoX3(L) (X = Cl, Br, I) and CoX2Y(L) (X = Cl Br; Y = Br I; X ≠ Y; L = monoprotonated 1-methyl and 2-methyl-piperazine) were prepared and investigated by means of magnetic and spectroscopic measurements. All the magnetic and spectroscopic results indicate that CoX3(L) complexes possess a pseudotetrahedral C3ν symmetry and the CoX2Y(L) complexes a Cs symmetry. On the basis of these symmetries the bands of their electronic spectra are assigned.Particular attention is paid in this work to the far-infrared spectra and the Co-X, Co-Y and Co-N vibrations of all the complexes are -assigned with a reasonable certainty.

F.Cariati; G.Marcotrigiano; L.Menabue; F.Morazzoni; G.C.Pellacani; G.M.Zanderighi ( 1978 ) - Solid state vibrational spectroscopy of some piperidinium and morpholinium salts of tin(IV), antimony(III) and bismuth(III) halide complexes. - SPECTROCHIMICA ACTA. PART A, MOLECULAR SPECTROSCOPY - n. volume 34A - pp. da 801 a 805 ISSN: 0584-8539 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some compounds of the type (LH)2SnX6 (X = Cl, Br), (LH)2SnX4Y2 , (LH)2MX5 (M = Sb, Bi; X = Cl, Br) and (LH)3M2I9 (M = Sb, Bi) (LH = piperidinium cation (pipdH) or morpholinium cation (morphH)) were prepared and characterized by means of the Raman and far-i.r. spectroscopy. The study of the vibrational spectra suggests for the hexahalo- and mixed-hexahalo-stannates(IV) an octahedral of trans-octahedral configuration, respectively. For the pentahaloantimonates(III) and bismuthates(III) the geometries of the complexes were found to depend on the hydrogen bonding ability of the counter cation. In fact the bismorpholiniumpentahalometallates(III) show square pyramidal configurations while the bispiperidinium complexes show octahedral configurations, in which two halogen atoms bridge the metals.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1978 ) - Spectroscopic investigation of the cobalt(II), nickel(II), copper(II) and zinc(II) tetrahalometallates of the N-ethyl-morpholinium cation. - TRANSITION METAL CHEMISTRY - n. volume 3 - pp. da 108 a 112 ISSN: 0340-4285 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Tetrahalo- and mixed tetrahalo-metallates of Co(II), Ni(II), Cu(II) and Zn(II) of the N-ethylmorpholinium cation were prepared and investigated by means of spectroscopic and magnetic measurements. While the cobalt(II), nickel(II) and zinc(II) complexes appear to be essentially, tetrahedral, the copper(II) complexes are discussed on the basis of a distorted ('flattened') tetrahedral symmetry. The electronic spectra of the complexes are assigned on this basis. The far i.r. spectra of the complexes show bands which are unambiguously assignable to the metal-halogen stretching modes. The effects of the counter cation on the geometry around the metal ion, compared with that of the morpholinium and piperidinium cations, are discussed in relation to the pKa of the amine.

G.Marcotrigiano;L.Menabue; P.Morini; G.C.Pellacani ( 1977 ) - alfa-N-benzoyl-DL-alaninate nickel(II) complexes. - BULLETIN DE LA SOCIETE CHIMIQUE DE FRANCE - n. volume no volume - pp. da 815 a 819 ISSN: 0037-8968 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A compound of the type Ni(Bz-alfa-ala)2 dihydrate and its mono- and bis- and tri-amine adducts were prepared. All the complexes seem to be six-coordinated with chromophore NiO6, in the case of binary complex, NiN6 in the case of tris-ethylenediamine adduct and NiO4N2 for the remaining amine adducts.

G.C.Pellacani; G.Peyronel; W.Malavasi; L.Menabue ( 1977 ) - Antimony and bismuth trihalide complexes of dithiomalonamide, N,N'-dimethyl- and N,N'-diphenyl-dithiomalonamide. - JOURNAL OF INORGANIC & NUCLEAR CHEMISTRY - n. volume 39 - pp. da 1855 a 1857 ISSN: 0022-1902 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some antimony and bismuth trihalide complexes of dithiomalonamide and its N,N’-alkyl and aryl derivatives have been isolated. The ligands were S,S-coordinated to the metal. Two IR bands due to M-S vibrations and some mass-dependent bands assignable to M-X modes were observed

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1977 ) - Benzoyl-beta-alaninato nickel(II) complexes. The amine effect on the amino acid coordination around the nickel ion. - BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN - n. volume 50 - pp. da 742 a 745 ISSN: 0009-2673 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A compound of the type Ni(Bz-β-ala)2·2H2O (Bz-β-ala=benzoyl-β-alaninate anion) and its amine adducts of the type Ni(Bz-β-ala)2Bn·xH2O (n=1; B=piperazine (pipz), 1,10-phenanthroline (o-phen) and x=2; n=1, B=2,2′-bipyridine (2,2′-bpy) and 4,4′-bipyridine (4,4′-bpy) and x=4; n=2, B=N-methylpiperazine (CH3-pipz), morpholine (morph), pyridine (py), 3-methylpyridine (3-pic) and 4-methylpyridine (4-pic) and x=2; n=3, B=en, and x=0) were prepared. Each complex was characterized by elemental analysis, solid spectroscopy and magnetic moment. All the complexes are six-coordinated and the presence of NiO6 and NiN6 chromophores for Ni(Bz-β-ala)2·2H2O and Ni(en)3(Bz-β-ala)2 complexes respectively and of NiO4N2 chromophores for the amine adducts is suggested. In all the complexes the amino acid appears to act as a bidentate ligand toward the carboxyl group. A ligand field strength in the aromatic heterocyclic amine adducts was found greater than in the aliphatic heterocyclic amine adducts. The amine adducts complexes appear to dissociate in solution with a change of the donor site, without changing in the stereochemistry, around the nickel ion.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1977 ) - Copper(II) complexes of peptide group containing amino acids. Bis(N-acetyl-L-alaninate)copper(II) complexes and their amine adducts. - JOURNAL OF INORGANIC & NUCLEAR CHEMISTRY - n. volume 39 - pp. da 1897 a 1901 ISSN: 0022-1902 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Bis(N-acetyl-L-alaninato)copper(II) monohydrate and its adducts with cyclic aliphatic and aromatic amines were prepared and characterized with the aim to define the chromophore and the effect of the N-donor ligand on the N-protected aminoacid coordination behavior. The coordination geometry in the solid state for CuL2B2, where L= N-acetyl.L-alaninate and B= amine is square planar or tetragonally elongated octahedral with CuN2O2 or CuN4 chromophore.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1977 ) - Far-IR spectra of the tetrahalocobaltate complexes of the morpholinium,piperidinium, 1-methyl- and 2-methyl-piperazinium cations. - JOURNAL OF INORGANIC & NUCLEAR CHEMISTRY - n. volume 39 - pp. da 2097 a 2098 ISSN: 0022-1902 [Articolo in rivista (262) - Articolo su rivista]
Abstract

We have studied the tetrahalocobaltate complexes of the morpholinium and piperidinium cations and of the 1-methyl- and 2-methyl-piperazinium dications. Their magnetic moments and electronic spectra suggest the presence of complexes having distorted tetrahedral symmetries and their IR spectra (4000-400 cm-1) indicate that the hydrogen bonding interactions are partly responsible for their distortion.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1977 ) - Study on the pseudotetrahedral and tetrahedral cobalt(II) complexes. - JOURNAL OF COORDINATION CHEMISTRY - n. volume 7 - pp. da 1 a 8 ISSN: 0095-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Pseudotetrahedral zwitterionic complexes of stoichiometry CoX3 (L+)(X = Cl, Br and I) and CoX2Y(L+) (X = Cl and Y = Br and I; X = Br and Y = I), where L represents the cationic ligand, were prepared and tetrahedral complexes of stoichiometry CoX4[L(+2)], where X = Cl, Br and I and L represents the cationic ligand. In the pseudotetrahedral zwitterionic complexes, the electronic spectra may be assigned assuming an effective C3v symmetry and the low symmetry ligand field is proposed to be less important than the spin-orbit coupling effects, vibronic coupling and Jahn–Teller distortions. The i.r. spectra of the zwitterionic complexes suggest a lack of influence of the cationic site on the ligand properties of the donor atom. The magnetic properties and electronic spectra of the CoX4[L(2+)] complexes were correlated and the ligand field strength (10Dq), the Racah parameters (B') and the spin-orbit coupling constants (λ') were calculated. From B' and λ' we obtained evidence that appreciable overlap of metal and ligand orbitals occurs in these complexes. In addition the far i.r. spectra and tentative assignments of Co–X and Co–N absorption are also discussed.

L.Antolini; L.Menabue; G.C.Pellacani ( 1976 ) - Apparent formation constants of dithiooxamide and substituted dithiooxamide complexes of cobalt(II,III), nickel(II) and copper(II) in strongly acidic media. - ANALYTICA CHIMICA ACTA - n. volume 83 - pp. da 337 a 342 ISSN: 0003-2670 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The apparent stability constants of the complex species formed between cobalt(II, III), nickel(II) or copper(II) and dithiooxamide or some N,N′- and tetra-substituted dithiooxamides have been determined in strongly acidic media at 25 ° C. The configuration of the complexes in solution is discussed on the basis of the electronic spectra

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1976 ) - Complexes of peptide-group containing amino acids N-acetyl-L-, alfa-N-benzoyl-DL- and N-benzoyl- beta-alaninate cobalt(II) complexes and their amine adducts. Trans.Met.Chem., 1, 229-233 (1976). - TRANSITION METAL CHEMISTRY - n. volume 1 - pp. da 229 a 233 ISSN: 0340-4285 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Cobalt(II) complexes of N-protected aminoacids and their amine derivatives were synthesized by means of spectroscopic and magnetic measurements.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1976 ) - Coordination properties of beta-alanine: new complexes with some transition metals: cobalt(II), nickel(II) and copper(II). - CANADIAN JOURNAL OF CHEMISTRY - n. volume 54 - pp. da 2426 a 2431 ISSN: 0008-4042 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The neutral six-coordinated tetragonal Co(β-ala)2•2H2O complex(β-ala = NH2CH2CH2COO−) was prepared. In this complex β-alanine acts as an O,N-chelating agent, as in the known Cu(β-ala)2•6H2O and Ni(β-ala)2•3H2O complexes. We also prepared some complexes of a type that is new for β-alanine, with stoichiometries such as M(β-alaH)2X2, M(β-alaH)4(ClO4)2 (M = Co and Ni), Cu(β-alaH)3(ClO4)2, and Cu(β-alaH)Cl2 in which the ligand acts as a zwitterion and coordinates toward the carboxy group as a formally neutral ligand. The possibility of formulating the complexes as H2[M(β-ala)2X2] is discussed. The electronic spectra and the magnetic moments of the halide complexes are in accord with pseudo-tetrahedral, octahedral, and tetragonal stereochemistry for the cobalt(II), nickel(II), and copper(II) ions, respectively, while those of the perchlorate complexes are in accord with pseudooctahedral stereochemistry. The β-alanine hydrohalide salts and the bis(β-alaninium)tetrachlorocuprate complex were also prepared and are discussed.

G.C.Pellacani; G.Peyronel; T.Feltri; L.Menabue ( 1976 ) - Copper(I) and silver(I) complexes of dithiomalonamide, N,N'-dimethyl- and N,N'-diphenyldithiomalonamide. - SPECTROCHIMICA ACTA. PART A, MOLECULAR SPECTROSCOPY - n. volume 32A - pp. da 285 a 289 ISSN: 0584-8539 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some copper (I) and silver (I) complexes with dithiomalonamide (Hdtma), NN′-dimethyl-(HMe2dtma) and NN′-diphenyl-dithiomalonamide (HPh2dtma) were prepared: Cu(Hdtma)X (X2 = Cl, Br, I(H2O), ClO4); Cu(HL)2X (HMe2dtma: X = Cl, Br, I, ClO4; HPh2dtma: X = Cl, Br, I); Ag(HL)X (Hdtma: X = Cl; HMe2dtma: X = Br, ClO4, BF4; HPh2dtma: X = Br, I); Ag2(HL)3X2 (Hdtma: X = ClO4, BF4; HMe2dtma: X = Cl; HPh2-dtma: X = Cl, ClO4); Ag2(HMe2dtma)I2 and Ag3(Hdtma)2Br3. Molar conductivities in DMF show that the complexes behave: M2(HL)3(ClO4)2 as 1:2 electrolytes, M(HL) (ClO4 of BF4) as 1:1 electrolytes; those of the halides Cu(HL)X and Cu(HL)2X, are almost equal and intermediate between values for non-electrolytes and 1:1 electrolites. Infrared spectra indicate an S,N-coordination for all the complexes: ν(MN) bands in the region of 400–500 cm−1 and ν(MS) bands in the region of 300–400 cm−1 (for Hdtma), 300–320 cm−1 (for HMe2dtma) and 260–280 cm−1 (for HPh2dtma) are observed. No ν(MX) bands were identified in the halide complexes indicating that a mental—halide coordination, if present in the solid complexes, should be very weak.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1976 ) - Infrared spectra (4000-60 cm-1) of the antimony(III) and bismuth(III) trihalide complexes with piperidine and piperazine. - JOURNAL OF MOLECULAR STRUCTURE - n. volume 30 - pp. da 85 a 94 ISSN: 0022-2860 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Antimony(III) and bismuth(III) halide complexes with heterocyclic amines (piperazine and piperidine) were synthesized and characterized by means of infrared spectra. The far-I.R. spectra enable to identify metal-halide and metal-N vibrations.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1976 ) - (N-benzoyl-DL-alaninate)copper(II) complexes: effects of amines on the amino acid coordination. - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 1627 a 1631 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Reaction of amines with the complex [Cu(Bz-AlaO)2]·H2O (Bz-AlaO =N-benzoyl-DL-alaninato) gives adducts of the type [Cu(Bz-AlaO)2]·Bn[n= 1,B = piperazine(ppz), 3-methylpyridine(3Me-py), 4Me-py, 2,2′-bipyridine (2,2′-bipy), 4,4′-bipy, and 1.10-phenanthroline (phen); n= 2, B = Meppz, piperidine (pip), morpholine (morp), py, and 4Me-py] and [Cu(en)2(Bz-AlaO)2]. Each complex has been characterized by elemental analysis, solid and solution spectroscopy, and magnetic moment. The complexes may be divided into three types from the point of view of their stereochemistry. Type (1) contains complexes having a copper(II) acetate monohydrate type co-ordination such as [{Cu(Bz-AlaO)2B}2][B = H2O, 3Me-py, 4Me-py, and py (only in solution)], type (2) contains complexes having a square-planar or strongly distorted tetragonal environment with a CuN2O2 chromophore such as [Cu(Bz-AlaO)2]·Bn(B = Meppz, pip, py, 4Me-py, 2,2′-bipy, and 4,4′-bipy) or a CuN4 chromophore such as [Cu(en)2(Bz-AlaO)2](the solution complexes of the Meppz, pip, mor, and 4Me-py adducts, which show a concentration-dependent colour change, are also discussed), and type (3) contains medium tetragonally distorted complexes, as the presence of two d–d bands supports, in the solid [Cu(mor)2(Bz-AlaO)2], solid and solution [Cu(Bz-AlaO)2]·phen, and in the presence of excess of amine, [CuB2(Bz-α-AlaO)2](B = Meppz, pip, mor, 3-Me-py, and 4-Me-py). For the phen adduct a cis-octahedral co-ordination with a CuN2O4 chromophore is proposed. while for the solution complexes in the presence of an excess of amine the CuN4O2 chromophore is suggested.

G.C.Pellacani; L.Menabue ( 1976 ) - Preparation and study of some dithiolylium salts - JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS - n. volume no volume - pp. da 455 a 459 ISSN: 0300-9246 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The salts 3,5-diamino- or 3,5-di(methylamino)-1,2-dithiolylium perchlorate or bromide and 4-chloro-(or 4-bromo-)3,5-diamino- or 3.5-di(methylamino)-1,2-dithiolylium chloride or bromide have been prepared by oxyation of dithiomalonamide or NN′-dimethyldithiomalonamide. Conductivity, molecular-weight, 1H n.m.r., u.v.,i.r., and polarographic measurements are reported. The removal of a proton from the CH2 group of the dithiomalonamides gives a five-membered ring with pseudo-aromatic character. All the experimental data support considerable π bonding between the sulphur atoms. and this confers great stability on the disulphide group. The stability of the 3,5-diamino-or 3,5-di(methylamino)-1,2- dithiolylium salts is greater than that of the 4-chloro-3, 5-diamino- or 3,5-di(methylamino)-1,2-dithiolylium salts. The reduction of these salts occurs in one two-electron wave. Mono- and bis-dithiolylium salts of tetrachloro-ferrate(III), -cobaltate(II), -niccolate(II), and -cuprate(II) have also been prepared. Their magnetic moments and electronic and i.r. spectra suggest a tetrahedral configuration for the [FeCl4]- anions and a distorted tetrahedral configuration for the [MCl4]2–(M = Co, Ni, or Cu) anions, and absence of co-ordination of the dithiolylium ions which act as cations.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1976 ) - Spectroscopic investigation of some halide and mixed-halide complexes of zinc(II), cadmium(II) and mercury(II) with piperidinium and morpholinium cations. - JOURNAL OF MOLECULAR STRUCTURE - n. volume 33 - pp. da 191 a 199 ISSN: 0022-2860 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The conductivities and IR spectra (4000-60 cm-1) of some complex halides of general formula A2MX4, A2MX2Y2 and ACdCl3 (A = piperidinium and morpholinium cation; M = Zn, Cd and Hg; X ? Y = Cl, Br and I) have been examined. The stereochemistry of the anions is inferred from the M-X frequency assignments. All the complexes tend to be tetrahedral and a lowering in Td symmetry is found in the morpholinium compared with the piperidinium complexes, owing to strong ionic interactions due to hydrogen bonds. In the CdCl3 - complexes the presence of bridge Cd-Cl vibrations, while in the mercury complexes the presence of terminal and bridge Hg-Cl vibrations, suggest the formation of dimeric or polymeric species

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1976 ) - Spectroscopic investigation on the trichloro-, tetrahalo- and mixed-tetrahalocuprates of the piperidinium and morpholinium cations. - JOURNAL OF COORDINATION CHEMISTRY - n. volume 5 - pp. da 189 a 194 ISSN: 0095-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some halo- and mixed-halo-cuprates of the type CuCl3 • L, CuCl4 • L2, CuCl3Br • L2, CuCl2Br2 • L2 and CuBr4 • L2, were prepared and characterized by means of far-i.r., i.r. and n.i.r. spectroscopy, magnetic moments and conductivity measurements. A band at 19000 cm−1, which appears only in the CuCl3 • L complexes, is characteristic of Cu2Cl2- 6 dimer or polymer species. For these complexes and for CuCl4(Morph)2 and CuCl3Br(Morph)2 (Morph = morpholinium cation) an approaching square-planar geometry, while for all the other complexes a distorted-tetrahedral geometry, may be suggested from their spectroscopic properties, compared to those of other tri- and tetra-halo-cuprates of known structure. An intermediate structure between these geometries may be proposed for the CuCl3 • Pipd complex. The planar geometry is probably stabilized by extensive NH … Cl hydrogen bonding interactions greater with the morpholinium cation than with the piperidinium cation. No thermochromic behaviour in the solid state in the 290–370° K temperature range is observed. The room-temperature magnetic moments agree with the proposed configurations.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1976 ) - Tetrahalo- and (mixed-tetrahalo)cuprates of the piperazinium dication.Coordination geometry changes in some CuX42- anions. - INORGANIC CHEMISTRY - n. volume 15 - pp. da 2333 a 2336 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some halo- and (mixed-halo)cuprates of the type (pipzH·HX)2CuY4 (X = Y = Cl, Br, X = Cl, Y = Br), (pipzH·HCl)2CuCl3Br (pipzH·HX = piperazinium monocation hydrohalide), (pipzH2)CuCl4, (pipzH2)CuCl3Br, (pipzH2)CuCl2Br2, (pipzH2)CuBr4, and (pipzH2)Cu2Cl6 (pipzH2 = piperazinium dication) were prepared and characterized by means of far-ir, ir, and near-ir spectroscopy, magnetic moments, and conductivity measurements. For the (pipzH·HX)2CuY4 and (pipzH·HCl)2CuCl3Br complexes, which are thermochromic, an approximately square-planar geometry may be suggested, while for the (pipzH2)CuXmYn (m + n = 4) complexes a distorted tetrahedral geometry may be suggested from the room-temperature spectroscopic properties of these compounds, compared to those of other tetrahalocuprates of known structure. The planar geometry is probably stabilized by extensive N-H?Cl hydrogen-bonding interactions, as is demonstrated by the change in the coordination geometry from square planar to distorted tetrahedral when the compounds are heated at 80-95°C or dissolved in dimethylformamide. In fact a weakening of the hydrogen-bonding network, caused by the increasing disorder due to the thermal motion or by a solvent effect, is responsible for the coordination geometry change. A band at 19 000 cm-1, which appears only in the (pipzH2)Cu2Cl6 complex, is characteristic of Cu2Cl6 2- dimer species. Also for this complex an approximately square-planar geometry is suggested

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1976 ) - Tetrahalocobaltate complexes of morpholinium, piperidinium, 1-methyl- and 2-methyl-piperazinium cations. - TRANSITION METAL CHEMISTRY - n. volume 1 - pp. da 167 a 170 ISSN: 0340-4285 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Some tetrahalocobaltate complexes of protonated heterocyclic aliphatic amines were prepared. Their magnetic moments and electronic spectra were discussed on the basis of distorted tetrahedral symmetry.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1975 ) - Bis(benzoyl-beta-alaninate)copper(II) complexes and their amine adducts. - INORGANICA CHIMICA ACTA - n. volume 19 - pp. da 133 a 137 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A compound of the type Cu(Bz-β-ala = benzoyl-β-alanine anion) was prepared. Amine adducts of the type Cu(Bz-β-ala)2Bn (n = 1 and B = pipz, 3-pic, 2,2′-bipy, 4,4′ and o-phen; n = 2 and B = Ch3- pipz, pipd, morph, py, 4-pic and en) were obtained by reaction of the amines with Cu(Bz-β-ala)2. Each complex was characterized by elemental analysis, and solution spectroscopy and magnetic moment. For the solid (Cu(Bz-β-ala)2B)N, solid and solution (Cu(Bz-β-ala)2B)·3-pic)2 and solution (Cu(Bz-β-ala)2B)2 (B = py and 4-pic) complexes the physical measurements support a copper acetate monohydrate type coordination. For the Cu(Bz-β-ala)2· o-phen complex in the solid state and in solution the presence of two bands (10500 and 14000 cm−1) in the electronic spectra and their position suggest a six-coordinate, cis-octahedral CuO4N2 chromophore, confirmed by the i.r. spectra which give evidence off bidentate coordination of the amino acid through the carboxylic group. The electronic spectra of all other complexes (one band at 15500-17000 cm−1 are consistent with the presence of square-planar (or strongly tetragonal distorted) coordination with CuO4N2 chromophores. I.r. spectra suggest a monodentate coordination of the amino acids and confirm the amine coordination toward the nitrogen atom. In the Cu(Bz-β-ala)2(en)2 complex a bidentate coordination of the en molecules with the formation of square planar species with CuN4 chromophores, with a weak monodentate interaction of the amino acid in the polar position is proposed. A concentration-dependent colour change with a red shift of the d-d band are also discussed for the solution (Cu(Bz-β-ala)2B)2 (B = py, 4-pic, Ch3-pipz, morph and pipd.

G.Marcotrigiano; L.Menabue; G.C.Pellacani ( 1975 ) - Zinc(II), cadmium(II) and mercury(II) complexes with N-acetyl-glycine (aceturic acid) and their amine adducts. - JOURNAL OF INORGANIC & NUCLEAR CHEMISTRY - n. volume 37 - pp. da 2344 a 2346 ISSN: 0022-1902 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The complexes of IIB metals with N-acetylglycine and their amine adducts are prepared and characterized by means of infrared spectra.

L.Menabue; G.C.Pellacani; G.Peyronel ( 1974 ) - ELECTRONIC AND FAR IR-SPECTRA OF SOME POLYMERIC COMPLEXES OF DITHIOOXAMIDE AND ITS N,N'-DISUBSTITUTED DERIVATIVES - INORGANIC AND NUCLEAR CHEMISTRY LETTERS - n. volume 10 - pp. da 187 a 191 ISSN: 0020-1650 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The metal complexes of dithiooxamide and its N,N'-derivatives were synthesized and characterized by means of electronic and far i.r. spectra.

G.C.Pellacani; G.Peyronel; G.Marcotrigiano; L.Menabue ( 1974 ) - Methylcellosolve (2-methoxy-ethanol) as solvent for conductivity measurements on coordination compounds. - JOURNAL OF INORGANIC & NUCLEAR CHEMISTRY - n. volume 37 - pp. da 1551 a 1552 ISSN: 0022-1902 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Methylcellosolve (2-methoxy-ethanol) (MCS) has a low donor ability and so is a better solvent for conductivity measurements as compared to nitrobenzene or dimethylsulphoxide. We have studied MCS in order to determine the molar conductivity ranges for 1:1, 2:1 and 3:1 electrolytes.

G.Claser; G.C.Pellacani; L.Menabue; G.Peyronel ( 1974 ) - Nickel(II) and copper(II) complexes with N,N'-diethyldithiooxamide: NiL X (X=Cl,Br,I,ClO4 ) ,CuLX (X=Cl,Br) and CuL (ClO4 ) . - GAZZETTA CHIMICA ITALIANA - n. volume 104 - pp. da 1095 a 1099 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Halide adducts of Nickel(II) and Copper(II) complexes with dithyooxamide derivatives were synthesized and characterized by means of different spectroscopic and magnetic measurements in order to define metal coordination geometry.