Foto personale

Pagina personale di Monica SALADINI

Dipartimento di Scienze Chimiche e Geologiche
Dipartimento di Scienze Chimiche e Geologiche - Sede Dipartimento di Scienze Chimiche e Geologiche

Orteca, Giulia; Tavanti, Francesco; Bednarikova, Zuzana; Gazova, Zuzana; Rigillo, Giovanna; Imbriano, Carol; Basile, Valentina; Asti, Mattia; Rigamonti, Luca; Saladini, Monica; Ferrari, Erika; Menziani, Maria Cristina ( 2018 ) - Curcumin derivatives and Aβ-fibrillar aggregates: An interactions’ study for diagnostic/therapeutic purposes in neurodegenerative diseases - BIOORGANIC & MEDICINAL CHEMISTRY - n. volume 26 - pp. da 4288 a 4300 ISSN: 0968-0896 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Several neurodegenerative diseases, like Alzheimer's (AD), are characterized by amyloid fibrillar deposition of misfolded proteins, and this feature can be exploited for both diagnosis and therapy design. In this paper, structural modifications of curcumin scaffold were examined in order to improve its bioavailability and stability in physiological conditions, as well as its ability to interfere with β-amyloid fibrils and aggregates. The acid-base behaviour of curcumin derivatives, their pharmacokinetic stability in physiological conditions, and in vitro ability to interfere with Aβ fibrils at different incubation time were investigated. The mechanisms governing these phenomena have been studied at atomic level by means of molecular docking and dynamic simulations. Finally, biological activity of selected curcuminoids has been investigated in vitro to evaluate their safety and efficiency in oxidative stress protection on hippocampal HT-22 mouse cells. Two aromatic rings, π-conjugated structure and H-donor/acceptor substituents on the aromatic rings showed to be the sine qua non structural features to provide interaction and disaggregation activity even at very low incubation time (2h). Computational simulations proved that upon binding the ligands modify the conformational dynamics and/or interact with the amyloidogenic region of the protofibril facilitating disaggregation. Significantly, in vitro results on hippocampal cells pointed out protection against glutamate toxicity and safety when administered at low concentrations (1 μM). On the overall, in view of its higher stability in physiological conditions with respect to curcumin, of his rapid binding to fibrillar aggregates and strong depolymerizing activity, phtalimmide derivative K2F21 appeared a good candidate for both AD diagnostic and therapeutic purposes.

Rigamonti, Luca; Orteca, Giulia; Asti, Mattia; Basile, Valentina; Imbriano, Carol; Saladini, Monica; Ferrari, Erika ( 2018 ) - New curcumin-derived ligands and their affinity towards Ga3+, Fe3+and Cu2+: Spectroscopic studies on complex formation and stability in solution - NEW JOURNAL OF CHEMISTRY - n. volume 42 - pp. da 7680 a 7690 ISSN: 1144-0546 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The metal complexing ability in solution of four substituted curcumin (CUR)-derived ligands K3T, originated by the insertion of the -CH2CH2COOtBu branch on the central atom of the diketonic moiety of CUR and related derivatives with variable meta and para substituents (OH, OMe, H, OCOCH3) on the peripheral aromatic rings, is examined. These molecules can act as new chelators with biological properties comparable to those of CUR but with improved stability. In fact, curcuminoids represent new perspectives for the development of novel therapeutic agents for several diseases including Alzheimer's disease. CUR showed neuroprotective properties, and a probable mechanism of its action is related to the complexation ability towards endogenous metal ions Fe3+and Cu2+. K3T derivatives retain the solvent-dependent diketo-ketoenol tautomerism, with the prevalence of the diketonic form in aqueous solution. They show enhanced stability in simulated physiological conditions (phosphate buffered solution at pH = 7.4) compared to CUR, together with similar or even higher anti-proliferative activity against human colon carcinoma cells HCT116. The addition of the metal ion causes dissociation of the enolic proton creating chelate complexes and shift of the tautomeric equilibrium toward the keto-enol species. The formation of metal complexes was followed and confirmed by both NMR (using Ga3+as a diamagnetic probe for Fe3+) and UV-visible spectroscopy. All the ligands showed high affinity for Fe3+and Ga3+, forming M:L 1:2 species. In view of therapeutic applications, notable is the good affinity of K3T31, i.e. the ligand bearing only OH groups in para positions of the aromatic rings, for Cu2+, and the ability of the Cu:K3T31 1:1 complex to bind to DNA.

Nardo, Luca; Maspero, Angelo; Penoni, Andrea; Palmisano, Giovanni; Ferrari, Erika; Saladini, Monica ( 2017 ) - Excited state dynamics of bis-dehydroxycurcumin tert-butyl ester, a diketo-shifted derivative of the photosensitizer curcumin - PLOS ONE - n. volume 12 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Bis-dehydroxycurcumin tert-butyl ester (K2T23) is a derivative of the natural spice curcumin. Curcumin is widely studied for its multiple therapeutic properties, including photosensitized cytotoxicity. However, the full exploitation of curcumin phototoxic potential is hindered by the extreme instability of its excited state, caused by very efficient non radiative decay by means of transfer of the enolic proton to the nearby keto oxygen. K2T23 is designed to exhibit a tautomeric equilibrium shifted toward the diketo conformers with respect to natural curcumin. This property should endow K2T23 with superior excited-state stability when excited in the UVB band, i.e., in correspondence of the diketo conformers absorption peaks, making this compound an interesting candidate for topical photodynamic therapy of, e.g., skin tumors or oral infections. In this work, the tautomeric equilibrium of K2T23 between the keto-enolic and diketo conformers is assessed in the ground state in several organic solvents by UV-visible absorption and by nuclear magnetic resonance. The same tautomeric equilibrium is also probed in the excited-state in the same environments by means of steady-state fluorescence and time-correlated single-photon counting measurements. These techniques are also exploited to elucidate the excited state dynamics and excited-state deactivation pathways of K2T23, which are compared to those determined for several other curcuminoids characterized in previous works of ours. The ability of K2T23 in photosensitizing the production of singlet oxygen is compared with that of curcumin.

Ferrari, Erika; Benassi, Rois; Saladini, Monica; Orteca, Giulia; Gazova, Zuzana; Siposova, Katarina ( 2017 ) - In vitro study on potential pharmacological activity of curcumin analogues and their copper complexes - CHEMICAL BIOLOGY & DRUG DESIGN - n. volume 89 - pp. da 411 a 419 ISSN: 1747-0277 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Curcumin and its derivatives have attracted great interest in the prevention and treatment of Alzheimer's disease, thanks both to the ability to hinder the formation of amyloid-beta (Aβ) aggregates and the ability to bind Cu (II) ion. In this article, we explore the ability of curcumin derivatives of K2T series to affect amyloid Aβ1-40 aggregation. These derivatives were obtained by introducing the t-butyl ester group through a methylenic spacer on the central carbon atom of the β-diketo moiety of curcumin frame. The studied curcuminoids were demonstrated to inhibit Aβ1-40 fibrillization at substoichiometric concentrations with IC50 value near that of curcumin. In addition, the antioxidant properties and DNA interaction of their Cu(II) complexes is evaluated. The structure of Cu(II)-K2T31 complex is also proposed on the basis of DFT calculation.

Rosa, Roberto; Tassi, Lorenzo; Orteca, G.; Saladini, Monica; Villa, Carla; Veronesi, Paolo; Leonelli, Cristina; Ferrari, Erika ( 2017 ) - Process Intensification by Experimental Design Application to Microwave-Assisted Extraction of Phenolic Compounds from Juglans regia L. - FOOD ANALYTICAL METHODS - n. volume 10 - pp. da 575 a 586 ISSN: 1936-9751 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Microwave-assisted extraction was applied to Juglans regia L. fresh male flowers and unripe walnut seeds to evaluate the total phenolic contents of the extracts as well as the percentage of water-soluble polyphenols. The research was planned using the Design of Experiments technique to investigate the role on the extraction efficiency of different parameters, such as temperature, time and number of microwave heating cycles, together with their possible interactions. Optimization was achieved by applying a Response Surface Methodology comprising a three-factor, two-level, full-factorial Face-Centred Central Composite Design. The two input variables with a significant effect on the recovery of phenols from fresh male flowers were the extraction temperature and the number of microwave cycles. In the case of unripe walnut seeds, a linear two-factor interaction model was selected, with significant interactions occurring between temperature and time, and time and number of microwave cycles. The best experimental conditions were as follows: 100 °C, 6 min, three microwave heating cycles and 22.7 ± 0.2 mg gallic acid equivalent (GAE)/g (total phenolic content, PC); energy consumption calculations suggested slightly different conditions: 60 °C, 30 min, three microwave heating cycles and 20.7 ± 0.3 mg GAE/g (TPC).

Romagnoli, Chiara; Prati, Fabio; Benassi, Rois; Orteca, Giulia; Saladini, Monica; Ferrari, Erika ( 2017 ) - Synthesis, characterization and metal coordination of a potential β-lactamase inhibitor: 5-Methyl-2-phenoxymethyl-3-H-imidazole-4-carboxylic acid (PIMA) - ARABIAN JOURNAL OF CHEMISTRY - n. volume 10 - pp. da 1061 a 1069 ISSN: 1878-5352 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Among relevant metal ions in biological systems, zinc and iron play a key role as active partners of the catalytic machinery. In particular, the inhibition of metal enzymes that are involved in physiological and pathological processes has been deeply investigated for the rational design of selective and efficient drugs based on chelators. Since imidazole histidine residue is one of the most versatile sites in proteins, especially in enzymes acting in the presence of metal ions as cofactors, in this work the synthesis and characterization of a new imidazole derivative, namely 5-methyl-2-phenoxymethyl-3-H-imidazole-4-carboxylic acid (PIMA) is reported. PIMA was designed as metallo-β-lactamase inhibitor thanks to its similarity with penicillin V, a β-lactam antibiotic inactivated by metallo-β-lactamase, for which there are no commercially available inhibitors. The evaluation of PIMA coordinating ability toward iron, zinc, and gallium, these latter selected as a non-paramagnetic probe for iron, is performed by theoretical DFT calculations and in solution by experimental techniques, i.e. potentiometry, UV-vis and NMR spectroscopy. PIMA exhibits an efficient metal chelating ability; the prevailing species in physiological condition are ML3 for Fe3+ and Ga3+ and ML2 for Zn2+, in which chelation is due to deprotonated carboxylic oxygen and imidazole nitrogen in the N,O donor set. The demonstrated ability of PIMA to chelate zinc ion, combined with its structure similarity with penicillin V, supports further exploration of this imidazole-4-carboxylate as metallo-β-lactamase inhibitor.

Rosa, Roberto; Zerazion, Elisabetta; Ferrari, Erika; Veronesi, Paolo; Leonelli, Cristina; Saladini, Monica; Ferrari, Anna Maria ( 2016 ) - Cradle to the grave Life Cycle Assessment of microwave assisted vs. conventional extraction for the obtainment of highly pure curcumin ( GENP 2016, the International Congress on Green Extraction of Natural Products - Torino - 31 Maggio – 1 Giugno 2016) ( - Atti dell' International Congress on Green Extraction of Natural Products ) [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

Microwave assisted extraction of natural compounds is widely recognized as one of the most promising green extraction techniques, even if comprehensive comparisons with more conventional procedures are surprisingly scarce, being on the other hand limited to mere considerations concerning extraction time and yield. In this work, “cradle to the grave” environmental assessments of microwave assisted compared to conventional Soxhlet-based extraction procedures will be presented, for the particular case of curcumin molecule, extracted from Curcuma longa L., in view of its important antioxidant, anti-inflammatory and anticancer properties. The Life Cycle Assessment (LCA) methodology was applied, since it allows evaluating the environmental consequences associated with all the stages of the extraction process, thus including the crop production of the Indian plant, the subsequent production of the dried rhizomes, their commercialization, their transport, all the energy consumptions needed, the necessary laboratory facilities and their maintenance, together with the chemicals needed and their disposal treatments. The study was then completed by also comparing the obtained results with those of a particular synthetic strategy of curcumin, in order to establish the most environmentally friendly production procedure of this fundamental phytochemical.

Rosa, Roberto; Zerazion, Elisabetta; Ferrari, Erika; Veronesi, Paolo; Villa, Carla; Saladini, Monica; Ferrari, Anna Maria; Leonelli, Cristina ( 2016 ) - Microwave-assisted extraction of phytochemicals ( The 3rd Global Congress on Microwave Energy Applications - Cartagena - Spagna - 25 - 29 Luglio 2016) ( - 3GCMEA - Atti del 3rd Global Congress on Microwave Energy Applications ) [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

Several epidemiological studies highlighted the importance of a diet based on fruits and vegetables, for a significant reduction in the risk of several human health diseases [1]. Therefore, the extraction of the so-called dietary phytochemicals started gaining an extraordinary research interest from both academia and industries, to the detriment of their synthesis, particularly when the concepts and principles of Green Extraction [2] and Process Intensification [3] are considered, in order to pursue a sustainable development. Among the green extraction techniques, the application of microwave energy is surely to be considered one of the most appealing ones, mainly as a direct consequence of its unique heating mechanism. According to the nature of the plant matrix as well as of the phytochemical compounds of interest, microwaves can be applied in a plenty of variants. Aim of the present work is to display some of our recent results obtained by microwave assisted extraction (MAE) of phenolic compounds from Juglans regia L., Cinnamomum Zeylanicum and Curcuma longa L. [4], highlighting the advantages, when any, over more conventional extraction procedures as well as over the chemical synthesis of those molecules, also in terms of energy consumptions as well as environmental assessments of these different approaches.

Zerazion, Elisabetta; Rosa, Roberto; Ferrari, Erika; Veronesi, Paolo; Leonelli, Cristina; Saladini, Monica; Ferrari, Anna Maria ( 2016 ) - Phytochemical compounds or their synthetic counterparts? A detailed comparison of the quantitative environmental assessment for the synthesis and extraction of curcumin - GREEN CHEMISTRY - n. volume 18 - pp. da 1807 a 1818 ISSN: 1463-9262 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Natural compounds represent an extremely wide category to be exploited, in order to develop new pharmaceutical strategies. In this framework, the number of in vitro, in vivo and clinical trials investigating the therapeutic potential of curcumin is exponentially increasing, due to its antioxidant, anti-inflammatory and anticancer properties. The possibility to obtain this molecule by both chemical synthesis and extraction from natural sources makes the environmental assessments of these alternative production processes of paramount importance from a green chemistry perspective, with the aim, for both industries and academia, to pursue a more sustainable development. The present work reports detailed and quantitative environmental assessments of three different curcumin production strategies: synthesis, conventional Soxhlet-based extraction (CE) and microwave-assisted extraction (MAE). The chemical synthesis of curcumin, as recently optimized by the authors, has been firstly evaluated by using the EATOS software followed by a complete “cradle to the grave” study, realized by applying the Life Cycle Assessment (LCA) methodology. The life cycles of CE and MAE were then similarly assessed, considering also the cultivation of Curcuma longa L., the production of the dried rhizomes as well as their commercialization, in order to firstly investigate the widely claimed green character of MAE with respect to more conventional extraction procedures. Secondly, the results related to the two different extraction strategies were compared to those obtained by the chemical synthesis of curcumin, with the aim to determine its greenest preparation procedure among those investigated. This work represents the first example of an environmental assessment comparison between different production strategies of curcumin, thus smoothing the way towards the highly desirable establishment of environmentally friendly rankings, comprising all the existing alternatives to the chemical synthesis of a target chemical compound.

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).

Marianne Lilletvedt Tovsen; Ellen Bruzell; Erika Ferrari; Monica Saladini; Vivek S. Gaware; Már Másson; Solveig Kristensen; Hanne Hjorth Tønnesen ( 2014 ) - Antibacterial phototoxic effects of synthetic asymmetric and glycosylated curcuminoids in aqueous formulations Studies on curcumin and curcuminoids. LIV - JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY - n. volume 140 - pp. da 150 a 156 ISSN: 1011-1344 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The aim of this study was to evaluate the in vitro phototoxic potential of synthetic asymmetric and glycosylated curcuminoids on planktonic model bacteria by counting the colony forming units. The Gram-positive Enterococcus faecalis and the Gram-negative Escherichia coli were exposed to aqueous solutions of the curcuminoids (≤ 2.5 μM) in the presence or absence of selected pharmaceutical excipients (Pluronic® F127, PEG 400 and HPγCD) in combination with a low irradiation dose (5 J/cm2). All the asymmetric curcuminoids, but only one of the glycosylated curcuminoids demonstrated substantial phototoxic effect on Enterococcus faecalis (≥ 4.7 log reduction). Only two of the asymmetric curcuminoids showed a moderate to low phototoxic effect on the more persistent Escherichia coli. This study emphasized that aromatic hydroxyl substituents in the para-position are important to maintain the phototoxic potential of curcuminoids independent of molecular symmetry. Glycosylation of the aromatic substituents resulted in a substantial loss in phototoxicity towards planktonic bacteria, an apparent change in the non-radiative S1-decay process and a weaker interaction with Pluronic® F127 compared to the non-glycosylated curcuminoids. The selected excipients Pluronic® F127, PEG 400 and HPγCD strongly influenced the phototoxic potential of the unsymmetrical, non-glycosylated compounds.

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 ( XII CONVEGNO NAZIONALE AIMAT - Lecce - 21-24 Settembre 2014) ( - 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.

Erika Ferrari;Rois Benassi;Stefania Sacchi;Francesca Pignedoli;Mattia Asti;Monica Saladini ( 2014 ) - Curcumin derivatives as metal-chelating agents with potential multifunctional activity for pharmaceutical applications - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 139 - pp. da 38 a 48 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Curcuminoids represent new perspectives for the development of novel therapeutics for Alzheimer's disease (AD), one probable mechanism of action is related to their metal complexing ability. In this work we examined the metal complexing ability of substituted curcuminoids to propose new chelating molecules with biological properties comparable with curcumin but with improved stability as new potential AD therapeutic agents. The K2T derivatives originate from the insertion of a -CH2COOC(CH3)3 group on the central atom of the diketonic moiety of curcumin. They retain the diketo-ketoenol tautomerism which is solvent dependent. In aqueous solution the prevalent form is the diketo one but the addition of metal ion (Ga3 +, Cu2 +) causes the dissociation of the enolic proton creating chelate complexes and shifting the tautomeric equilibrium towards the keto–enol form. The formation of metal complexes is followed by both NMR and UV–vis spectroscopy. The density functional theory (DFT) calculations on K2T21 complexes with Ga3 + and Cu2 + are performed and compared with those on curcumin complexes. [Ga(K2T21)2(H2O)2]+ was found more stable than curcumin one. Good agreement is detected between calculated and experimental 1H and 13C NMR data. The calculated Osingle bondH bond dissociation energy (BDE) and the Osingle bondH proton dissociation enthalpy (PDE), allowed to predict the radical scavenging ability of the metal ion complexed with K2T21, while the calculated electronic affinity (EA) and ionization potential (IP) represent yardsticks of antioxidant properties. Eventually theoretical calculations suggest that the proton-transfer-associated superoxide-scavenging activity is enhanced after binding metal ions, and that Ga3 + complexes display possible superoxide dismutase (SOD)-like activity.

Asti, Mattia; Ferrari, Erika; Croci, Stefania; Atti, Giulia; Rubagotti, Sara; Iori, Michele; Capponi, Pier C.; Zerbini, Alessandro; Saladini, Monica; Versari, Annibale ( 2014 ) - Synthesis and characterization of 68Ga-labeled curcumin and curcuminoid complexes as potential radiotracers for imaging of cancer and alzheimers disease - INORGANIC CHEMISTRY - n. volume 53 - pp. da 4922 a 4933 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Curcumin (CUR) and curcuminoids complexes labeled with fluorine-18 or technetium-99m have recently shown their potential as diagnostic tools for Alzheimer’s disease. Gallium-68 is a positron-emitting, generator-produced radionuclide, and its properties can be exploited in situ in medical facilities without a cyclotron. Moreover, CUR showed a higher uptake in tumor cells compared to normal cells, suggesting potential diagnostic applications in this field. In spite of this, no studies using labeled CUR have been performed in this direction, so far. Herein, 68Ga-labeled complexes with CUR and two curcuminoids, namely diacetyl-curcumin (DAC) and bis(dehydroxy)curcumin (bDHC), were synthesized and characterized by means of experimental and theoretical approaches. Moreover, a first evaluation of their affinity to synthetic β-amyloid fibrils and uptake by A549 lung cancer cells was performed to show the potential application of these new labeled curcuminoids in these diagnostic fields. The radiotracers were prepared by reacting 68Ga3+ obtained from a 68Ge/68Ga generator with 1 mg/mL curcuminoids solutions. Reaction parameters (precursor amount, reaction temperature, and pH) were optimized to obtain high and reproducible radiochemical yield and purity. Stoichiometry and formation of the curcuminoid complexes were investigated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, NMR, ultraviolet–visible, and fluorescence spectroscopy on the equivalent natGa-curcuminoids (nat = natural) complexes, and their structure was computed by theoretical density functional theory calculations. The analyses evidenced that CUR, DAC, and bDHC were predominantly in the keto–enol form and attested to Ga(L)2+ species formation. Identity of the 68Ga(L)2+ complexes was confirmed by coelution with the equivalent natGa(L)2+ complexes in ultrahigh-performance liquid chromatography analyses.68Ga(CUR)2+, 68Ga(DAC)2+, and 68Ga(bDHC)2+ were highly (87 ± 4, 90 ± 1%) and moderately (48 ± 2%), respectively, retained by synthetic β-amyloid fibrils in vitro. All the Ga-curcuminoid complexes showed an uptake in A549 lung cancer cells, at least equivalent to the respective free curcuminoids, confirming potential applications as cancer-detecting radiotracers.

Basile V; Belluti S; Ferrari E; Gozzoli C; Ganassi S; Quaglino D; Saladini M; Imbriano C. ( 2013 ) - bis-Dehydroxy-Curcumin Triggers Mitochondrial-Associated Cell Death in Human Colon Cancer Cells through ER-Stress Induced Autophagy. - PLOS ONE - n. volume 8 - pp. da 1 a 18 ISSN: 1932-6203 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Background: The activation of autophagy has been extensively described as a pro-survival strategy, which helps to keep cells alive following deprivation of nutrients/growth factors and other stressful cellular conditions. In addition to cytoprotective effects, autophagy can accompany cell death. Autophagic vacuoles can be observed before or during cell death, but the role of autophagy in the death process is still controversial. A complex interplay between autophagy and apoptosis has come to light, taking into account that numerous genes, such as p53 and Bcl-2 family members, are shared between these two pathways. Methodology/Principal Findings: In this study we showed a potent and irreversible cytotoxic activity of the stable Curcumin derivative bis-DeHydroxyCurcumin (bDHC) on human colon cancer cells, but not on human normal cells. Autophagy is elicited by bDHC before cell death as demonstrated by increased autophagosome formation -measured by electron microscopy, fluorescent LC3 puncta and LC3 lipidation- and autophagic flux -measured by interfering LC3-II turnover. The accumulation of poly-ubiquitinated proteins and ER-stress occurred upstream of autophagy induction and resulted in cell death. Cell cycle and Western blot analyses highlighted the activation of a mitochondrial-dependent apoptosis, which involves caspase 7, 8, 9 and Cytochrome C release. Using pharmacological inhibitions and RNAi experiments, we showed that ER-stress induced autophagy has a major role in triggering bDHC-cell death. Conclusion/Significance: Our findings describe the mechanism through which bDHC promotes tumor selective inhibition of proliferation, providing unequivocal evidence of the role of autophagy in contrasting the proliferation of colon cancer cells.

Erika Ferrari; Mattia Asti; Rois Benassi; Francesca Pignedoli; Monica Saladini ( 2013 ) - Metal binding ability of curcumin derivatives: a theoretical vs. experimental approach - DALTON TRANSACTIONS - n. volume 42 - pp. da 5304 a 5313 ISSN: 1477-9234 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Theoretical calculations employing DFT at the B3LYP/6-311G++** level are used to investigate the tautomeric equilibrium in curcumin derivatives. The solvent effect is evaluated using the CPCM continuum solvation method. The results are compared with experimental data obtained from the X-ray crystal structure of K2A23 and UV-vis data. The KE tautomer is more stable in a vacuum and in the solid state, while in water the DK tautomer reaches a population of 90%. In agreement with spectroscopic data, theoretical calculations predict a slight prevalence of the DK form in non-aqueous solvent systems. The ability to chelate metal ions [Fe3+, Ga3+ and Cu2+] is then explored by means of 1H, 13C NMR and UV-Vis spectroscopy. From the calculation of the overall stability constants of metal complexes and 1H NMR titrations with Ga3+, it is clear that the more stable species has a 1 : 2 M/L molar ratio. The curcuminoid coordinates the metal ion through the keto–enol function in the dissociated form; in addition 2D 1H 13C NMR experiments suggest the involvement of carboxylic oxygen in metal coordination it was found in the solid state for the complex [Ga(K2A33)2]PF6. The rate of the complexation reaction is strongly influenced by the type of substituent on the aromatic ring of the curcuminoid (K2A33 ≈ K2A23 ≫ K2A21). In addition DPPH assay evidences how antioxidant ability of curcumin derivatives is mainly due to the presence of a phenolic group and metal coordination by a keto–enolic moiety does not affect it, especially for K2A21.

E. Ferrari; M. Asti; G. Malavasi; C. Imbriano; F. Pignedoli; M. Bonavia; D. Daquino; M. Saladini ( 2012 ) - Development of new metal-based phyto-radiopharmaceuticals: diagnostic agents derived from Cur(e)cumin ( XL Congresso Nazionale della Divisione di Chimica Inorganica - Sestri Levante (GE) - 9-13 settembre 2012) ( - Atti del Congresso ) (Società Chimica Italiana Genova ITA ) - pp. da 50 a 50 ISBN: XXXXXXXXXX ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Curcumin, a yellow pigment extracted from the Indian spice Curcuma longa, has been widely linked with suppression of angiogenesis, inflammation, cardiovascular diseases, tumorigenesis and A-binding activities in the context of therapies for Alzheimer’s disease [1,2]. Besides, Curcumin has shown interesting binding ability towards different metal ions such as Fe(III) and Ga(III) with the involvement of its keto-enolic moiety [3]. Metal complexation triggers an increased kinetic stability and bioavailability of Curcumin in physiological conditions, reducing one of its main drawbacks in therapeutic applications. Anyway biologically active curcuminoids have little been investigated as labelled radiopharmaceuticals for cancer diagnosis or therapy, and they represent a novelty in the field. In this presentation we show an overview of new classes of Curcumin-based ligands with bidentate and tridentate coordinating mode, we investigate their binding ability towards Rhenium and Gallium and report a complete thermodynamic and pharmaco-kinetic study on ligands and metal complexes with the aim of developing new radiopharmaceuticals.

Nardo, Luca; Maspero, Angelo; Selva, Marco; Bondani, Maria; Palmisano Giovanni; Ferrari, Erika; Saladini, Monica ( 2012 ) - Excited-State Dynamics of bis-dehydroxycurcumin Carboxylic Acid, a Water-Soluble Derivative of the Photosensitizer Curcumin. - JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY - n. volume 116 - pp. da 9321 a 9330 ISSN: 1089-5639 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Bis-dehydroxycurcumin carboxylic acid (K2A23) is a synthetic curcuminoid designed to exhibit enhanced water solubility and photosensitizing potential with respect to natural curcumin. In this work, the tendency of the compound to form intra- and intermolecular hydrogen bonds in the ground state is studied by UV−visible absorption and by nuclear magnetic resonance (NMR). The excited-state dynamics of the drug are probed in different environments by means of time-correlated single-photon counting measurements and related to its hydrogen bonding affinity in the excited state.

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 ) ( Nanotechnology 2012: Bio Sensors, Instruments, Medical, Environment and Energy - 2012 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2012 - Santa Clara CA - 18-21 June 2012) ( - 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.

E. Ferrari; O. Francioso; S. Nardi; M. Saladini; N. Dal Ferro; F. Morari ( 2011 ) - DRIFT and HR MAS NMR characterization of humic substances from a soil treated with different organic and mineral fertilizers. - JOURNAL OF MOLECULAR STRUCTURE - n. volume 998 - pp. da 216 a 224 ISSN: 0022-2860 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this study, using DRIFT and HR MAS NMR, we analyzed the humic substances isolated from a soil treated, over 40 years, with different organic, mineral and organic plus mineral treatments and cultivated with maize as the main crop. As expected, the structure of humic substances was very complex but by combining both techniques (DRIFT and HR MAS NMR) additional information was obtained on aromatic and aliphatic components, the most recalcitrant parts of these macromolecules. In so doing we wanted to investigate the relationship between HS structure and long-term management practices. An elevated content of lignin, aminoacids, peptides and proteins was observed mainly for farmyard manure treatments with respect to mineral or liquid manure amendments; this supports how the different management practices have greatly influenced the humification process of cultivated soils.

R. Benassi; E. Ferrari; S. Lazzari; F. Pignedoli; F. Spagnolo; M. Saladini ( 2011 ) - How glucosylation triggers physical–chemical properties of curcumin: an experimental and theoretical study. - JOURNAL OF PHYSICAL ORGANIC CHEMISTRY - n. volume 24 - pp. da 299 a 310 ISSN: 0894-3230 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In the present study, we investigate the structures of glucosylated curcumin derivatives with DFT at B3LYP/6-31G*level. A conformational analysis is performed in order to determine the conformational minimum (GS) and rotationaltransition state (TS) of curcumin derivatives and then their electronic features are evaluated. HOMO and LUMOfrontier orbitals and maps of electron density potential (MEPs) are plotted and compared. In order to correlate theirpredicted spectroscopic properties with IR, UV–vis and NMR experimental data we extended the theoretical study onelectronic properties to different solvents (H2O, MeOH, ACN, DMSO). The main finding is that the curcuminic coremaintains the same geometrical and electronic structures in all compounds miming the metal coordination capabilityshowed by curcumin. Therefore, wemay confirm that the presence of glucose does not affect the electronic propertiesof the derivatives.

Erika Ferrari; Francesca Pignedoli; Carol Imbriano; Gaetano Marverti; Valentina Basile; Ettore Venturi; Monica Saladini ( 2011 ) - Newly synthesized curcumin derivatives: crosstalk between chemico-physical properties and biological activity. - JOURNAL OF MEDICINAL CHEMISTRY - n. volume 54 - pp. da 8066 a 8077 ISSN: 0022-2623 [Articolo in rivista (262) - Articolo su rivista]
Abstract

New curcumin analogues (ester and acid series) were synthesized with the aim to improve the chemical stability in physiological conditions and potential anticancer activity. Cytotoxicity against different tumorigenic cell lines (human ovarian carcinoma cells – 2008, A2780, C13* and A2780/CP - and human colon carcinoma cells - HCT116 and LoVo) was tested to evaluate cellular specificity and activity.Physico/chemical properties such as acidity, lipophilicity, kinetic stability and free radical scavenging activity were investigated to shed light on the structure-activity relationship and provide new attractive candidates for drug development. Most of ester derivatives show IC50 values lower than curcumin and exhibit selectivity against colon carcinoma cells. Especially they are extremely active after 24h exposure showing enhanced inhibitory effect on cell viability.The best performances of ester curcuminoids could be ascribed to their high lipophilicity that favors a greater and faster cellular uptake overcoming their apparently higher instability in physiological condition.

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 ( XXXIX Congresso Nazionale di Chimica Inorganica - XXIV Congresso Nazionale della Società Chimica Italiana - Lecce - 11-15 Settembre 2011) ( - 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

Ferrari, Erika; Saladini, Monica; Pignedoli, Francesca; Spagnolo, Ferdinando; Benassi, Rois ( 2011 ) - Solvent effect on keto-enol tautomerism in a new B-diketone: a comparison between experimental data and different theoretical approaches. - NEW JOURNAL OF CHEMISTRY - n. volume 35 - pp. da 2840 a 2847 ISSN: 1144-0546 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The novel -diketo compound (3-acetyl-4-oxopentanoic acid) OPAA is here synthesized, completely characterized in the solid state by means of X-ray crystallography and in solution by potentiometry and 1H and 13C NMR spectroscopy. In the solid state, OPAA exhibits the di-keto (DK) structure, while in solution a strongly solvent dependent tautomeric equilibrium is observed. Theoretical ab-initio calculations employing DFT at B3LYP/6-311G** level and different methods of theoretical model chemistry (CBS-4M, G3MP2, CBS-QB3) are used to extensively investigate the tautomeric equilibrium in comparison with experimental data. Solvent effects are evaluated using CPCM continuum solvation method; among all implied methods, CBS-4M is the one that better predicts experimental data and is able to qualitatively describe tautomeric equilibrium in solution, allowing thermodynamic calculation of pKa. Furthermore a supermolecular solvent approach is used to better analyze solvent-solute interactions in order to forecast chemical properties.

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.

Francesca Pignedoli; Fabio Zobi; Monica Saladini; Roger Alberto ( 2010 ) - New 99mTc(I) and Re(I) Curcumin derivatives for molecular imaging - NUCLEAR MEDICINE AND BIOLOGY - n. volume 37 - pp. da 683 a 683 ISSN: 0969-8051 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Re(I) complexs with curcumin is here discussed

M. Caselli; E. Ferrari; C. Imbriano; F. Pignedoli; M. Saladini; G. Ponterini ( 2010 ) - Probing solute–solvent hydrogen bonding with fluorescent water-soluble curcuminoids - JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. A, CHEMISTRY - n. volume 210 - pp. da 115 a 124 ISSN: 1010-6030 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Glycosylated water-soluble curcuminoids (C1–C3, first scheme of this article) differing in the 3,3-ringsubstituents (–OH, –OCH3 and H) equilibrate between the di-keto and the keto–enol forms. The formerare well observable in the absorption spectra in water, but their emissions are always negligible. Theketo–enol forms of C1–C3 exhibit a broad range of fluorescence quantum yields in different solvents,organic and water: formation of solute–solvent hydrogen bonds through the 3,3-ring substituents maychange the radiationless S1-state decay constant by up to a factor 200. Such a fluorescence quenchingmechanism is extremely efficient in water and, for C1, in accepting organic media. On the contrary, noeffects traceable to intermolecular hydrogen bonds involving the central -dicarbonyl moiety have beenobserved. So, fluorescence of these curcuminoids may probe the hydrogen bonding ability, particularly asacceptor, of their microenvironments, including hydrophilic/hydrophobic domains in complex biologicalsystems. Interaction of C1 and C2 with bovine serum albumin results in emission enhancements inverseto the quantum yields of the curcuminoids in water. The observations support the idea that, although thecurcuminoid microenvironment within its complex with the protein is less polar and hydrogen bondingthan water itself, residual water/ligand hydrogen bonds are active in enhancing radiationless transitions.Finally, fluorescence confocal images of HCT116 cells treated with C1–C3 suggest the apparently smallstructural differences to affect, besides their fluorescence behaviour, their interactions and fate withinliving cells.

E. Ferrari; F. Pignedoli; S. Lazzari; C. Imbriano; G. Marverti; M. Saladini ( 2009 ) - Development of new metal-chelating multi target drus derived from Curcumin ( XXII Congresso Nazionale della società chimica italiana - Sorrento (NA) - 5-10 Luglio 2009) ( - Atti del Congresso ) (Società chimica italiana Napoli ITA ) - pp. da 251 a 251 ISBN: / ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

With the aim to develop new anti-cancer approaches, which encompass therapies based on drug combinations, we are searching for innovative anti-tumor multi-targets treatments.1 In this research Curcumin represents our referring and starting point for the design of new derivatives. Curcumin, a natural occurring molecule, was shown to inhibit growth of several types of malignant cells and its biological activity was also related to its iron chelating ability.2 Recently curcumin proceeded onto clinical trials however its use is limited by a poor bioavailability. In order to improve curcumin water solubility and drug-delivery we have synthesized new derivatives which conjugate anti-proliferative effects with metal chelating capacity. They are able to reduce free iron level and to potentially deliver a chemotherapic metal ion such as Ga(III).

E. Ferrari; F. Pignedoli; C. Imbriano; M. Saladini ( 2009 ) - Development of new therapeutic Metal(III)-chelating agents derived from Curcumin ( Book of abstracts of "First International Conferece on Metal chelation in Biology and medicine" - Bath (UK) - 11-14 Dicembre 2009) ( - First International Conferece on Metal chelation in Biology and medicine ) (/ Bath GBR ) - pp. da 79 a 79 ISBN: / ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

With the aim to develop new anti-cancer approaches, which encompass therapies based on drug combinations, we are searching for innovative anti-tumor multi-targets treatments.1 In this research Curcumin represents our referring and starting point for the design of new derivatives. Curcumin, a natural occurring molecule, was shown to inhibit growth of several types of malignant cells and its biological activity was also related to its iron chelating ability.2,3 Recently curcumin proceeded onto clinical trials however its use is limited by a poor stability and bioavailability. In order to improve these features, we have synthesized new derivatives which potentially conjugate anti-proliferative and anti-oxidant effects with metal chelating capacity, especially towards Fe(III) and Ga(III), reducing free iron level and potentially delivering a chemotherapic metal ion such as Ga(III). We have performed a complete characterization of the chelating ability of new ligands in vitro by means of potentiometry, UV-Vis spectroscopy and NMR spectrometry. Stability and cellular uptake together with cytotoxicity towards different cell lines were also investigated for all ligands and their Ga(III) complexes in order to shed light on their potential anti-cancer effects especially against human colon cancer cells, unravelling the molecular basis of their biological activity.

E. Ferrari; S. Lazzari; F. Pignedoli; M. Saladini; O. Verna; A. Corradi; C. Leonelli; R. Rosa; P. Veronesi ( 2009 ) - Microwave assisted synthesis of new β-diketo derivatives ligands ( Zing, Microwave and Flow Chemistry Conference - Antigua - 28-31 Gennaio 2009) ( - Atti del Zing, Microwave and Flow Chemistry Conference ) (x xx ATG ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

The metal complexes of β-diketo derivatives and especially those of acetylacetone are well known and have been extensively studied. To improve the chelating ability of this molecule, we have introduced a further coordinative group. The designed compounds, which include a carboxylic group and the β-diketo moiety, are promising candidates as new metal ligands for pharmaceutical applications. Classical synthetic strategy for the obtainment of these adducts requires a two step procedure consisting first in the SN2 reaction of methylenic group and second deprotection of ester derivatives in order to set the carboxylic function free. Concerning the first step, traditional approach requires long reaction times and long work up procedures that lead to very poor product yields. Microwave (MW) irradiation at 2.45 GHz in closed vessels was exploited in this first synthetic step to take advantages from rapid heating rates thanks to the intrinsic volumetric and selectivity nature of MW heating. Results in terms of reaction times and yields as well as possible future developments, will be discussed.

M. Saladini; S. Lazzari; F. Pignedoli; R. Rosa; F. Spagnolo; E. Ferrari ( 2009 ) - New Synthetic Glucosyl-Curcuminoids, and their 1Hand 13C NMR Characterization, from Curcuma longa L. - PLANT FOODS FOR HUMAN NUTRITION - n. volume 64 - pp. da 224 a 229 ISSN: 0921-9668 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Turmeric extracts, among which curcumin and bisdemethoxycurcumin, are by far known for their therapeutic activities. In this study we propose easy and low cost synthetic pathways in order to obtain glucosyl-curcuminoids, safe and water soluble potential drugs and dyes, which may be implied in different fields ranging from pharmacology to food chemistry. The complete 1H and 13C NMR characterization of naturally occurring curcumin, bis-demethoxycurcumin and new synthetic glucosyl-curcuminoids is reported.

E. Ferrari; M Saladini; P. Gioacchini; O. Francioso; C. Ciavatta; S. Sohi; D. Powlson; G. Tonon ( 2009 ) - Structural investigation of organic matter in physical soil fractions from two broadleaf forests by High Resolution Magic Angle Spinning NMR ( International Symposium on Soil Organic Matter Dynamics: Land Use, Management and Global Change - Colorado Springs, Colorado - 6-9 Luglio 2009) ( - Atti del International Symposium on Soil Organic Matter Dynamics: Land Use, Management and Global Change ) (xx xx USA ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

1H HR MAS NMR is a powerful technique that allows to examine the chemical and physical properties of heterogeneous and polydisperse macromolecular systems such as soil organic matter (SOM). SOM plays a major role in the fate, transport, and bioavailability of organic and inorganic components and its dynamics depends on its chemical composition as well as by physical protection mechanisms with the soil fractions. Soil pH seems to be a variable that affects the SOM decomposition progression by influencing microbial activity, hydrolysis and protonation processes. Protonation regulates many soil processes such as solubilisation and complexation which controls sorption and desorption of organic C on mineral surfaces. Despite its documented importance as factor influencing SOM transformation and despite the high frequency of acid soil in forest ecosystems the effect of pH on SOM dynamics has been studied rather little. In the present study 1H HR/MAS NMR is applied to SOM extracted from two forest soils differing mainly for soil pH: the acid site, called Gesscroft, and the calcareous site, called Broadbalk. The two soils were physically fractionated according to Sohi’s procedure. Only the SOM of three fractions for each site was investigated: free light fraction (FLF), light fraction (IALF) and fine silt and clay (S+C); in fact they represented together the 70-80% of the total SOM in our soils and the organic C content was above the threshold value of the 3%, needed to obtain good signal/noise ratios in NMR spectra. 2-D 1H-1H homo-correlation spectroscopy (COSY), 1H-13C heteronuclear single quantum coherence (HSQC) and 1-D experiments were assessed for both a qualitative and a quantitative analysis of the soil matter. For both sites the S/N (signal to noise) ratio is higher for FLF-SOM and IALF-SOM with respect to S+C-SOM fractions in agreement with the decrease in carbon content. Amino acid residues, peptides and carbohydrates are the prevalent species and 6 typical chemical shift regions can be identified for each sample. Although S+C-SOM fractions of both sites show a finely decomposed matter, which is confirmed by the presence of sharp peaks, in particular the decrease in aromatic content of Gesscroft extracts with respect to Broadbalk ones suggests that the effect of acid pH seems to be relevant for degradation processes.

Erika Ferrari; Beatrice Arezzini; Marco Ferrali; Sandra Lazzari; Francesca Pignedoli; Ferdinando Spagnolo; Monica Saladini ( 2009 ) - Synthesis and characterization of glucosyl-curcuminoids as Fe3+ suppliers in the treatment of iron deficiency - BIOMETALS - n. volume 22 - pp. da 701 a 710 ISSN: 0966-0844 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The Fe3+ chelating ability of some curcumin glucosyl derivatives (Glc-H; Glc-OH; Glc-OCH3) is tested by means of UV and NMR study. The pK a values of the ligands and the overall stability constants of Fe3+ and Ga3+ complexes are evaluated from UV spectra. The only metal binding site of the ligand is the β-diketo moiety in the keto-enolic form; the glucosyl moiety does not interact with metal ion but it contributes to the stability of metal/ligand 1:2 complexes by means of hydrophilic interactions. These glucosyl derivatives are able to bind Fe3+ in a wide pH rage, forming complex species thermodynamically more stable than those of other ligands commonly used in the treatment of iron deficiency. In addition they demonstrate to have a poor affinity for competitive biological metal ions such as Ca2+. All ligands and their iron complexes have a good lypophilicity (log P > −0.7) suggesting an efficient gastrointestinal absorption in view of their possible use as iron supplements in oral therapy. The ligand molecules are also tested for their antioxidant properties in “ex vivo” biological system.

Erika Ferrari; Sandra Lazzari; Gaetano Marverti; Francesca Pignedoli; Ferdinando Spagnolo; Monica Saladini ( 2009 ) - Synthesis, cytotoxic and combined cDDP activity of new stable curcumin derivatives - BIOORGANIC & MEDICINAL CHEMISTRY - n. volume 17 - pp. da 3043 a 3052 ISSN: 0968-0896 [Articolo in rivista (262) - Articolo su rivista]
Abstract

New curcumin derivatives are synthesized in order to improve chemical properties of curcumin. The aromatic ring glycosylation of curcumin provides more water-soluble compounds with a greater kinetic stability which is a fundamental feature for drug bioavailability. The glycosylation reaction is quite simple, low cost, with high yield and minimum waste. NMR data show that the ability of curcumin to coordinate metal ion, in particular Ga(III), is maintained in the synthesized products. Although the binding of glucose to curcumin reduces the cytotoxicity of the derivatives towards cisplatin (cDDP)-sensitive and -resistant human ovarian carcinoma cell lines, the compounds display a good selectivity since they are much less toxic against non-tumourigenic Vero cells. The combination of cDDP with the most active glycosyl-curcuminoid drug against both cDDP-sensitive and -resistant as well as against Vero cell lines is tested. The results show an improvement of cDDP efficacy with higher selectivity towards cancer cells than non-cancer cells. These studies indicate the need for developing new valid components of drug treatment protocols to cDDP-resistant cells as well.

M. Saladini; E. Ferrari; S. Lazzari; F. Pignedoli; F. Spagnolo ( 2008 ) - Fe(III) containing complexes with beta-diketo derivatives for treatment of iron deficiency ( XXXV Congresso Nazionale della Divisione di Chimica Inorganica della Società Chimica Italiana - Milano - 3-7 Settembre 2007) ( - Atti del XXXV Congresso Nazionale della Divisione di Chimica Inorganica della Società Chimica Italiana ) (xx Milano ITA ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

...

Beatrice Arezzini; Marco Ferrali; Erika Ferrari; Chiara Frassineti; Sandra Lazzari; Gaetano Marverti; Ferdinando Spagnolo; Monica Saladini ( 2008 ) - Synthesis, chemical and biological studies on new Fe3þ-glycosilated b-diketo complexes for the treatment of iron deficiency - EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY - n. volume 43 - pp. da 2549 a 2556 ISSN: 0223-5234 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A simple synthetic pathway to obtain glycosilated b-diketo derivatives is proposed. These compounds show a good iron(III) affinity thereforewe may suggest the use of their Fe3þ-complexes as oral iron supplements in the treatment of anaemia. The glycosilated compounds (6-GlcH, 6-GlcOH and 6-GlcOCH3) are characterized by means of spectroscopic (UV, 1H and 13C NMR) and potentiometric techniques; they have a good water solubility, are kinetically stable in physiological condition (t1/2 > 100 h) and show a low cytotoxicity also in high concentrations (IC50 > 400 mM). They are able to bind Fe3þ ion in acid condition (pHw2) forming complex species thermodynamically more stable than those of other ligands commonly used in the treatment of iron deficiency. The iron complexes show also a good kinetic stability both in acidic and physiological pH and have a good lypophilicity (log P > 0.7) that suggests an efficient gastrointestinal absorption in view of their possible use in oral therapy. In addition they demonstrate a poor affinity for competitive biological metal ion such as Ca2þ, and in particular 6-GlcOCH3 is able to inhibit lipid peroxidation.

R. Benassi ; E. Ferrari; S. Lazzari; F. Spagnolo; M. Saladini ( 2008 ) - Theoretical study on Curcumin: A comparison of calculated spectroscopic properties with NMR, UV–vis and IR experimental data - JOURNAL OF MOLECULAR STRUCTURE - n. volume 892 - pp. da 168 a 176 ISSN: 0022-2860 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The main target of this study is a high-level computational nalysis of Curcumin, employing DFT approach with two different sets of basis functions (B3LYP/6-31G* and B3LYP/6-311G**). Accurate quantum mechanical studies, both in vacuum and in methanol medium, are carried out with the aim to analyze the conformational equilibria, to find the most stable equilibrium structure and to define the nature of the molecular orbitals, fundamental to explain Curcumin binding characteristic. Our theoretical calculations, performed at B3LYP/6-31G* and B3LYP/6-311G** levels both in vacuum and in methanol medium,confirm that the keto-enolic forms are more stable than the di-keto one, whose extremely low population suggests that this structure should not influence Curcumin properties. Keto-enolic form C results the most stable, independently on calculation level and solvent (methanol) effect. HOMO and LUMO molecularorbitals are calculated for all the structures with the two sets of basis with very similar results. MEPs show that the negative charge is localized on the oxygen atoms, which, in the keto-enolic forms, point in the same direction enabling metal coordination.NMR, UV–vis and FT-IR experimental data are employed in the comparison with electronic and conformational properties of Curcumin resulting from theoretical calculations. The two different calculation levels (B3LYP/6-31G* and B3LYP/6-311G**) give very similar results.Good linear correlations between the experimental 1H and 13C NMR chemical shifts (dexp), in methanold4(MeOD) and DMSO-d6 (DMSO), and calculated magnetic isotropic shielding tensors (sigmacalc) are found (dexp = a *signacalc + b). A good prediction of UV–vis experimental maximum absorption (lambdamax) on the basisof conformer populations is obtained. A linear relation with a good correlation coefficient is observedplotting the FT-IR experimental wavenumbers vs. the calculated ones, allowing to predict FT-IR spectra.

FERRARI, Erika; GRANDI, Romano; LAZZARI, Sandra; SALADINI, Monica ( 2007 ) - NMR study on Pt(II) interaction with Amadori compounds - INORGANICA CHIMICA ACTA - n. volume 360 - pp. da 3119 a 3122 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

AbstractHere we report the first evidence of Pt(II) interaction with Amadori compound [N-(1-deoxy-d-Fructos-1-yl)glycine (Fru-Hgly)]. The 1H and 195Pt NMR results show that complexation of Pt(II) by Fru-Hgly is strongly dependent on pH and reaction molar ratio. In 1/1 Pt/Fru-Hgly molar ratio, at acidic pH, the first coordination site is the carboxylic oxygen, while at physiological pH the anchoring group is the aminic one, in both cases the system slowly evolves towards an N,O chelating mode. In 1/2 Pt/Fru-Hgly molar ratio the only coordination site is nitrogen atom while the carboxylic oxygen is not involved in metal coordination.

P. Gioacchini; E. Ferrari; D. Montecchio; O. Francioso; M. Saladini; C. Ciavatta ( 2007 ) - Soil amendament with olive wastes-effects on mineral N, microbial biomass and humic acids structure ( P11. “International Symposium on Organic Matter Dynamics in Agro-Ecosystems” - Poiters - France - 16-19 Luglio 2007) ( - Atti del P11. “International Symposium on Organic Matter Dynamics in Agro-Ecosystems” ) (xx Poiters FRA ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

...

R. Benassi; E. Ferrari; R. Grandi; S. Lazzari; M. Saladini ( 2007 ) - Synthesis and characterization of new beta-diketo derivatives with iron chelating ability - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 101 - pp. da 203 a 213 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Here we report the synthesis, the characterization and a theoretical study on new glycosylated phenyl substituted beta-diketones; two classes of compounds are obtained according to the condensation reaction: central and side derivatives. Their iron(Ill) chelating ability is tested by means of UNT-visible (UV-vis), potentiometric and NMR techniques. The conformation of central derivatives does not allow any metal chelation, while side derivatives bind iron(111) through the P-dioxo moiety. The glycosyl moiety does not interact with metal ion but it helps to stabilize metal/ligand (1/3) complexes by means of hydrophylic interactions. The pK(a) of the ligands and the stability constants of their Fe(111) complexes are evaluated by means of UV-vis spectroscopy and potentiometry. A comparison with other iron-chelating agents, on the basis of lipophilicity and the pFe(III), is finally reported. (c) 2006 Elsevier Inc. All rights reserved.

O. FRANCIOSO; E. FERRARI; M. SALADINI; D. MONTECCHIO; P.GIOACCHINI; C. CIAVATTA ( 2007 ) - TG–DTA, DRIFT and NMR characterization of humic-like fractions from olive wastes and amended soil” (Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598 ) - JOURNAL OF HAZARDOUS MATERIALS - n. volume 149 - pp. da 408 a 417 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The purpose of the present study is to investigate, by means of thermogravimetric analysis (TG) and differential thermal analysis (DTA), diffuse reflectance infrared Fourier transform (DRIFT) and 2D nuclear magnetic resonance (NMR) spectroscopies, the structural features of the humic-like fraction (HLF) from olive pulp (OP), its effluents originated from the fermentation processes for hydrogen (EH2) and methane production (ECH4) and humic acid (HA) from soil amended with each of these materials. A considerable structural modification emerged between the HLF, in particular from the ECH4 effluent, which was characterised by a high content of polyphenolic and polypeptidic substances. The short-term amendment trial with OP and EH2 indicated that no chemical or structural changes in soil HA appeared. In contrast, the amendment with ECH4 substantially influenced the chemical and structural composition of soil HA. The structural interpretation performed by 2D NMR indicated the presence of aliphatic and aromatic protons while the sugar-like content and O–CH3 groups decreased with respect to the soil control HA. It emerges from this study that olive wastes contain stabilised humic-like material that may be recycled as an amendment in areas where olive trees are cultivated.

E.FERRARI; R.GRANDI; S.LAZZARI; G. MARVERTI; C. ROSSI; M. SALADINI ( 2007 ) - 1H, 13C, 195Pt NMR study on platinum(II) interaction with sulphur containing Amadori compounds - POLYHEDRON - n. volume 26 (15) - pp. da 4045 a 4052 ISSN: 0277-5387 [Articolo in rivista (262) - Articolo su rivista]
Abstract

AbstractThe NMR study on the interaction of Pt(II) with Amadori compounds is performed. The Amadori compounds are derived from the reaction of β-d-glucose with l-cystine leading to N,N′-di-(1-deoxy-β-fructos-1-yl)-l-cystine [FruCyscys], and with l-methionine leading to N-(1-deoxy-β-fructos-1-yl)-l-methionine [FruMet].The great instability of 2-(1,2,3,4,5-pentahydroxypentyl)-1,3-thiazolidine-4-carboxylic acid [GlcCys], formed by the condensation reaction of β-d-glucose and l-cysteine, prevents the formation of its Pt(II) complexes. Differently, FruMet well reacts with K2PtCl4 in 1:1 M/L molar ratio leading to the formation of [Pt(FruMet-N,S)Cl2], in which the Amadori compound coordinates the metal ion through nitrogen and sulphur atoms. FruMet originates also a solid trans complex [Pt(FruMet-N,S)2]Cl2. Its NMR solution study allowed to identify two isomers with respect to nitrogen and sulphur atoms: R,R and S,S.In [Pt2FruCyscysCl4] species, FruCyscys molecule links two Pt(II) ions giving rise to two pentaatomic N,S-chelate rings.

E. Ferrari; C. Frassineti; S. Lazzari; G. Marverti; R. Grandi; M. Saladini ( 2006 ) - Glucosyl curcuminoid derivatives: Fe(III) and Ga(III) chelating agents with anti-cancer properties ( 1st European Chemistry Congress - Budapest - 27-31 Agosto 2006) ( - Atti del 1st European Chemistry Congress ) (xx Budapest HUN ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

...

E. Ferrari; C. Frassineti; S. Lazzari; G. Marverti; R. Grandi; M. Saladini ( 2006 ) - Glucosyl curcuminoid derivatives: Fe(III) and Ga(III) chelating agents with anti-cancer properties ( EUROBIC8 – 8th European Biological Inorganic Chemistry Conference - Aveiro - Portogallo - 1-6 Luglio 2006) ( - Atti del EUROBIC8 – 8th European Biological Inorganic Chemistry Conference ) (xx Aveiro PRT ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

...

E. Ferrari; R. Grandi; S. Lazzari; M. Saladini ( 2005 ) - Hg(II)-coordination by sugar-acids: Role of the hydroxy groups - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 99 - pp. da 2381 a 2386 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A solution study on the ability of some derivatised sugars [glucuronic acid (GluA), galacturonic acid (GalA) and glucosaminic acid (GlNA)] to complex the Hg(II) ion is reported. The stability constants of the complex species were determined by potentiometric measurements while H-1 NMR experiments allow to define the coordination sites of sugar molecules. GluA coordinates the metal ion through the carboxylic oxygen and the O-4 hydroxyl group and is found to form more stable complexes with respect to GalA in which metal ligation is from the carboxylic oxygen and the O-5 ring oxygen. GlNA forms stable complexes chelating Hg(II) ion through carboxylic oxygen and the a-amino group. The ternary 2,2´-bipyridine containing systems were also investigated by means of potentiometric studies. The ML2 complexes were also isolated in the solid state and characterised by IR spectroscopy.

R. Benassi; E. Ferrari; R. Grandi; S. Lazzari; M. Saladini ( 2005 ) - New conjugated beta-diketones as iron chelators for clinical use ( 1st European Conference on Chemistry for life sciences - Rimini - 4-8 ottobre 2005) ( - Atti del 1st European Conference on Chemistry for life sciences ) (xx Rimini ITA ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

...

E. Ferrari; R. Grandi; S. Lazzari; M. Saladini ( 2005 ) - New water soluble conjugated beta-diketones: potential iron-sequestering agents in treatment of Cooley’s anemia ( 8th FIGIPAS – Meeting in inorganic chemistry - Atene - 6-9 Luglio 2005) ( - Atti del 8th FIGIPAS – Meeting in inorganic chemistry ) (xx Atene GRC ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

...

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.

B. Arezzini; M: Ferrali; E. Ferrari; R. Grandi; S. Monti; M. Saladini ( 2004 ) - Glycosyl-curcuminoids as potential new chelating agents in iron overload chelation therapy - EUROPEAN JOURNAL OF INORGANIC CHEMISTRY - n. volume 3 - pp. da 646 a 652 ISSN: 1434-1948 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The iron(III) chelating ability of some glycosyl derivatives of curcuminoids is tested by means of UV, potentiometric and NMR studies. The pK(a) of the ligands and the stability constants of their Fe3+ and Ga3+ complexes are evaluated by UV spectroscopy. The only metal binding site of the ligand is the beta-dioxo moiety; the glycosyl moiety does not interact with the metal ion at acidic pH values but it helps to stabilise metal/ligand (1:2) complexes by means of hydrophilic interactions. By comparing the pFe(3+) of our ligands with those reported for other chelating agents we suggest using these molecules as pro-drugs in iron overload treatment. Some of the more water-soluble derivatives are also tested for their antioxidant properties in vitro in biological systems and proved to act as free-radical scavengers inhibiting the iron redox cycle, ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).

E. Ferrari; M. Saladini ( 2004 ) - Iron(III) complexing ability of carbohydrate derivatives - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 98 - pp. da 1002 a 1008 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A solution study on the coordinative ability of galactaric acid (GalAH(2)), D-glucosamine (GlcN) and D-glucosaminic acid (GlcNAH) toward Fe3+ ion is reported. UV spectroscopic study provides useful information to identify complex species formation and their stability constants are determined by means of potentiometric measurements. GalAH(2) behaves as chelating ligand through carboxylic oxygen and alpha-hydroxylic oxygen in the protonated or dissociated form depending on pH value. Two complex species [Fe(2)GalA(OH)(4)] and Na[FeGalAH(-2)](.)2H(2)O are also isolated in the solid state and characterised through IR spectroscopy. Glc-NAH also binds the Fe3+ ion through carboxylic and hydroxylic groups, while NH2 group is probably involved in metal coordiantion up to pH 4. GlcN demonstrates low ligating ability at acidic pH and does not prevent metal hydroxyde precipitation.

E. Ferrari; S. Lazzari; M. Saladini ( 2004 ) - The reaction of Pt(II) with glucosyl-sulphur-containing amino acids ( XXXII Congresso nazionale della divisione di Chimica Inorganica - Roma - 20-24 Settembre 2004) ( - Atti del XXXII Congresso nazionale della divisione di Chimica Inorganica ) (XX Roma ITA ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

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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

E. Ferrari; R. Grandi; S. Monti; M. Saladini ( 2003 ) - New water soluble curcumin derivatives as iron(III) chelating agents ( 7th FIGIPS – Meeting in Inorganic Chemistry - Lisbona - 11-14 Luglio 2003) ( - Atti del 7th FIGIPS – Meeting in Inorganic Chemistry ) (xx Lisbona PRT ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

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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 ( XXX Congresso nazionale della divisione di Chimica Inorganica - Modena - 15-19 settembre 2002) ( - 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.

M. Borsari; E. Ferrari; R. Grandi; M. Saladini ( 2002 ) - Curcuminoids as potential new iron-chelating agents: spectroscopic, polarographic and potentiometric study on their Fe(III) complexing ability - INORGANICA CHIMICA ACTA - n. volume 328 - pp. da 61 a 68 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The pK(a) values of curcumin and diacetylcurcumin are, here doubtless, determined by means of spectroscopic and potentiometric measurements, and the enolic proton is the more acidic one. The interaction of Fe3+ with curcumin and diacetylcurcumin, in water/methanol 1:1 solution, leads to the fort-nation of the complex species [FeH2CU(OH)(2)] and [FeDCU(OH)(2)] (H2CU and DCU = curcumin or diacetylcurcumin monoanion, respectively) which prevails near pH 7. At more basic condition the prevailing species are [FeH2CU(OH)(3)](-) and [FeDCU(OH)(3)](-), which prevent metal hydroxide precipitation. H-1 NMR data state that the dissociated P-diketo moiety of the ligands is involved in metal chelation. The pK(a) value of the deprotonation reaction is strongly anticipated by the metal ion, as shown by UV spectral data. The stability constants, evaluated from potentiometric data, are near to that of desferrioxamine, which is, by now, the only iron-chelating agent for clinical use. (C) 2002 Elsevier Science B.V. All rights reserved.

E. Ferrari; R. Grandi; M. Saladini ( 2002 ) - Potential Iron(III)-chelating agents for treatment of Iron overload ( 35th International Conference on Coordination Chemistry ICCC35 - Heidelberg - 21-26 luglio 2002) ( - Atti del 35th International Conference on Coordination Chemistry ICCC35 ) (University of Heidelberg Heidelberg DEU ) - pp. da 391 a 391 ISBN: XXXXXXXXXX ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

...

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.

E. Ferrari; R. Grandi; M. Saladini ( 2002 ) - Synthesis and characterization of new glycosyl-curcuminoids ligands with iron(III) chelating ability ( VII Convegno sulla chimica dei carboidrati - Milano - 13-15 Giugno 2002) ( - Atti del VII Convegno sulla chimica dei carboidrati ) (xx Milano ITA ) [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

....

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.

M. Borsari; C. Gabbi; F. Ghelfi; R. Grandi; M. Saladini; S. Severi; F. Borella ( 2001 ) - Silybin, a new iron-chelating agent - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 85 - pp. da 123 a 129 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Silybin, a natural occurring flavolignan isolated from the fruits of Silibum marianum, has been reported to exert antioxidant and free radical scavenging abilities. It was suggested to act also as an iron chelator. The complexation and protonation equilibria of the ferric complex of this compound have been studied by potentiometric, spectrophotometric and electrochemical techniques. The formation of the complex silybin-Ga(III) in anhydrous DMSO-d6 has been studied by H-1 NMR spectroscopy. Mass spectrometry and infrared spectroscopy on silybin-Fe(III) complex confirm all data obtained by H-1 NMR spectroscopy. The experimental results show that silybin binds Fe(III) even at acidic pH. Different ternary complexes were observed at increasing methoxide ion concentration and their stability constants have been calculated. The results show the possible role of silybin in relation to the chelation therapy of chronic iron overload, as occurs in the treatment of Cooley's anemia. (C) 2001 Elsevier Science B.V. All rights reserved.

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.

G. Battistuzzi; M. Cannio; M. Saladini; R. Battistuzzi ( 2001 ) - Synthesis, crystal and molecular structure, spectroscopic and electrochemical studies of trichloro-oxo(4,6-dimethypyrimidine-2(1H)-thione)(triphenylphosphine oxide) rhenium(V) complex. - INORGANICA CHIMICA ACTA - n. volume 320 - pp. da 178 a 183 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Reaction of 4,6-dimethylpyrimidine-2(1H)-thione (Me2pymSH) with mer-[ReOCl3(Me2S)(OPPh3)] synthon in 1:1 molar ratio inrefluxing acetone, results in the replacement of the Me2S ligand to form the mer-[ReOCl3(Me2pymSH)(OPPh3)] species. X-raydiffraction shows that the structure of the title compound consists of monomeric units with a distorted octahedral coordinationaround the rhenium(V) centre which includes the axial ReO and ReOPPh3 bonds, and in which three Cl− ions and aS-monodentate neutral Me2pymSH ligand act as equatorial ligands. The compound was also characterised using electrochemicalmeasurements and UV–Vis–NIR and IR spectroscopy.

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.

R. Battistuzzi; M. Saladini ( 2000 ) - Structure of trans-diisothiocyanato(ethoxo)oxo-bis(triphenylphosphine)rhenium(V) complex - INORGANICA CHIMICA ACTA - n. volume 304 - pp. da 114 a 117 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The title compound consists of [ReO(NCS)(2)(OEt)(PPh3)(2)] units in which the rhenium(V) center shows a slightly distorted octahedral coordination. The two N-coordinated NCS- groups are trans to each other, as the Re=O and the Re-Oft units. The Re=O and Re-OEt bond lengths [1.682(10) and 1.871(10) Angstrom, respectively] and the geometry about the ethoxide oxygen atom indicate that in both cases M-O ligation has a considerable degree of multiple bond. (C) 2000 Elsevier Science S.A. 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 - Roma - 23-24 settembre 1999) ( - 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

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. Battistuzzi; A. Bonamartini Corradi; D. Dallari; M. Saladini; R. Battistuzzi ( 1998 ) - Synthesis, Crystal and Molecular Structure, Spectroscopic and Electrochemical Studies of -oxo-bis{oxo-bis(4,6-dimethylpyrimidine-2-thiolate)rhenium(V)} Complex - POLYHEDRON - n. volume 18 - pp. da 57 a 63 ISSN: 0277-5387 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The dinuclear oxo!rhenium"V#\ m!OReO"Me1pymS#11 species was prepared by the reaction of 3\5!dimethylpyrimidine!1"0H#!thione "Me1pymSH# with trans!ReI1"EtO# "PPh2#1 or trans!ReO1py3Cl=1H1O in di}erent solvents[ The compounds were char!acterized by elemental analysis\ magnetic susceptibility\ UV!VIS\ IR and 0H NMR spectroscopy and conductivity measurements[Cyclic voltammetry shows that the m!OReO"Me1pymS#11 species\ undergo a quasi!reversible single!electron process in which theoxygen!bridged dimeric framework is maintained[ The structure of m!OReO"Me1pymS#11 was determined by single!crystal X!raydi}raction methods[ The dinuclear structure of Re1O2"Me1pymS#3 compound consists of two ReO"Me1pymS#1 moieties bridgedby an oxygen atom[ The backbone O1ReORe1O is almost linear and each rhenium"V# ion lies in the center of a distortedoctahedron achieved through two deprotonated N\S!chelate ligands in the equatorial plane[ 0888 Elsevier Science Ltd[ All rightsreserved[

AB Corradi; MR Cramarossa; M. Saladini ( 1997 ) - Design, synthesis, structural and thermal characterisation of polymeric chlorocadmate(II) compounds with one-dimensional inorganic chain structures - INORGANICA CHIMICA ACTA - n. volume 257 - pp. da 19 a 26 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The chlorocadmate(II) compounds of formula (Hmepd) [CdCl3] (1) (Hmepd=1-methylpiperidine cation), (H(2)meen)(2)[Cd2Cl8]. H2O (2) (H(2)meen=N-methylethylenediamine dication) and (H(2)amepz) [Cd2Cl6(H2O)(2)] (3) (H(2)amepz=1-amino-4-methylpiperazine dication) are synthesised and their structural and thermal properties investigated. Compound 1 crystallises in space group P2(l)/a. The unit cell dimensions are a=15.046(2), b=10.408(2) and c=6.786(3) Angstrom, beta=92.39(2)degrees, Z=4. The final R value is 0.0353 (Rw=0.0328). Its structure consists of one-dimensional polymeric chains of face sharing CdCl6 octahedra running along the c axis and methylpiperidinium cations. Compound 2 crystallises in the C2/c space group. The unit cell dimensions are a=18.459(2), b=6.986(3) and c=18.167(2) Angstrom, beta=115.95(2)degrees, Z=4. The final R value is 0.0296 (Rw=0.0330). Its crystal structure consists of polymeric chains of [CdCl4](2-) anions running along the b axis, organic cations and non-coordinated water molecules. Compound 3 crystallises in the P2(1)/a space group, with a=7.542(2), b=14.658(4) and c=8.052(2) Angstrom, beta=106.91(3)degrees, Z=2. The final R value is 0.0330 (Rw=0.0340). The crystal structure consists of organic cations and polymeric chains of edge-sharing CdCl5 (H2O) octahedra. In compounds 1 and 2 hydrogen bond interactions between the inorganic chains, the organic cations and the water molecules, if present, contribute to the crystal packing, while in compound 3 this contribution comes from the contacts less than 3.5 Angstrom. The thermal characterisation is also discussed. The structures are compared with other examples of chlorocadmate(II) compounds.

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.

D. BRAGHIROLI; E. MUSSATI; M. DI BELLA; M. SALADINI ( 1996 ) - Asymmetric synthesis of 2-methyltaurine - TETRAHEDRON-ASYMMETRY - n. volume 7 - pp. da 831 a 836 ISSN: 0957-4166 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Enantiomeric (R)- and (S)-2-aminopropanesulfonic acids, 4a and 4b, were prepared in good yields and high enantiomeric purities (>99% ee) from (S)-5a and (R)-1-amino-2-propanol 5b respectively, using a four step synthesis. The absolute configuration of(S)-enantiomer 4b was established by X-ray analysis.

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.

A.BONAMARTINI CORRADI; M.R.CRAMAROSSA; M. SALADINI; L.P. BATTAGLIA; J. GIUSTI ( 1995 ) - ONE-DIMENSIONAL POLYMERIC CHLOROCADMATE(II) SYSTEMS OF N-METHYLPIPERAZINIUM AND N,N'-DIMETHYLPIPERAZINIUM COMPOUNDS - SYNTHESIS, STRUCTURAL AND THERMAL-PROPERTIES - INORGANICA CHIMICA ACTA - n. volume 230 - pp. da 59 a 65 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The chlorocadmate(II) systems of (H(2)me(2)pipz)[Cd2Cl6(H2O)(2)] (1) and (H(2)mepipz)(2)[Cd3Cl10(H2O)] (2) (L=me(2)pipz=N,N'-dimethylpiperazine; L'=mepipz=N-methylpiperazine) were prepared and their structural and thermal properties investigated. Compound 1 is monoclinic, space group P2(1)/c, a=7.664(1), b=7.472(4), c=15.347(1) Angstrom, beta-99.468(7)degrees, Z=2, R=0.024. The crystal structure consists of organic cations and infinite one-dimensional chains of [CdCl3(H2O)](3-)(n) anions. Each Cd atom is octahedrally surrounded by bridged and terminal chlorine atoms and by a water molecule, which is in trans position with respect to the terminal chlorine atom. Inter- and intrachain hydrogen bond interactions between the terminal chlorine atoms and the water molecules contribute to the crystal packing. Compound 2 is orthorhombic, space group Cmc2(1), a=15.286(3), b=13.354(3), c=13.154(3) Angstrom, Z=4, R=0.023. The crystal structure consists of organic dications and infinite chains of [Cd2Cl6(CdCl4H2O)](4-)(n) units running along the [001] axis. Each unit is formed of regularly alternate six-coordinated Cd atoms, one of them linking one pentacoordinated Cd atom which completes its coordination through a water molecule. A strong hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential scanning calorimetry measurements did not show the presence of any structural phase transitions. The structures are compared with those of (H(2)pipz)[Cd2Cl6(H2O)(2)] (3), (H(2)mepipz)[Cd2Cl6(H2O)(2)]. H2O (4) and (H(2)mepipz)[Cd2Cl6] (5) (L=pipz=piperazine,L'=mepipz=N-methylpiperazine).

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).

A.BONAMARTINI CORRADI; M.R.CRAMAROSSA; M. SALADINI; J.GIUSTI; A.SACCANI; F.SANDROLINI ( 1995 ) - Synthesis, thermal and electrical characterization of 2-methylpentane-1,5- diammonium tetrachlorocadmate(II) with perovskite-like structure - INORGANICA CHIMICA ACTA - n. volume 233 - pp. da 85 a 90 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper reports the synthesis and the structural, thermal and electrical characterization of the 2-methyl-pentane-1,5-diammonium bidimensional chlorocadmate(II) system with perovskite-like structure. Its structure consists of layers of CdCl6 corner-sharing octahedra extending in the ab plane. Interposed sheets of organic dications link adjacent layers through hydrogen bonding and contribute to the crystal packing. The presence of a methyl group on the C(4) atom of the organic chain is considered responsible for the thermal stability of the compound between room and melting temperature (605 K). The compound behaves as an electrical insulator at low temperature approaching semiconducting values at higher temperature. These results are also compared with those found for other structurally similar compounds.

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.

SALADINI M ( 1994 ) - TRANS-TETRAAQUABIS(P-NITROHIPPURATO)-COBALT(II) DIHYDRATE - ACTA CRYSTALLOGRAPHICA. SECTION C, CRYSTAL STRUCTURE COMMUNICATIONS - n. volume 50 - pp. da 1561 a 1563 ISSN: 0108-2701 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Crystals of [Co(4-NO2-hip)2(H2O)4].2H2O (4-NO2-hip = p-NO2.C6H4CO.NHCH2CO2-) contain molecules of the centrosymmetric octahedral cobalt(II) complex and lattice water molecules which are interlinked by hydrogen bonds. The Co atom lies on a crystallographic symmetry centre and has a slightly elongated octahedral environment arising from coordination by the carboxylic O atoms of two monodentate 4-nitrophippurate anions and the O atoms of four water molecules.

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.

SALADINI M ( 1993 ) - CRYSTAL AND MOLECULAR-STRUCTURE, AND INFRARED STUDY OF BIS(2,2'-BIPYRIDINE) [N-(TOLUENE-P-SULFONYL)GLYCINATO-NO] CADMIUM(II) COMPLEX AND RELATED-COMPOUNDS - JOURNAL OF CRYSTALLOGRAPHIC AND SPECTROSCOPIC RESEARCH - n. volume 23 - pp. da 551 a 554 ISSN: 0277-8068 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A series of complexes of formula [M(II)(bpy)2(ArSO2-N-aminoacidato-NO)1.3H2O [bpy = 2,2'-bipyridine, M(II) = Zn(II), ArSO2 N-aminoacidato NO = N(toluene-p-sulfonyl)- and N(benzenesulfonyl)-glycinate NO dianion,hereafter abbreviated as tsgly-NO and bsgly-NO, respectively, M(II) = Cd(II), ArSO2-N-aminoacidato-NO = tsgly-NO] was separated and investigated by spectroscopic and X-ray methods. The crystal structure of [Cd(bpy)2(tsgly-NO)].3H2O was determined. The compound crystallizes in the monoclinic space group P2(1)/n, Z = 4, a = 15.427(4), b = 13.580(2), c = 15.546(4) angstrom, beta = 110.97(3), R = 0.041, R(w) = 0.043. The structure consists of monomeric, approximately octahedral [Cd(bpy)2(tsgly-NO)] units with a N5O donor atom set, which gives rise to three almost orthogonal five-membered chelate rings. The IR spectra suggest similar environments for all the complexes.

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.

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.

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.

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. Forti; M. Saladini; M. Sola ( 1991 ) - Solid state behaviour of N-tosyl-DL-asparagine-Cu(II)-2,2'-bipyridine system - INORGANICA CHIMICA ACTA - n. volume 187 - pp. da 197 a 200 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The structural and spectroscopic properties of [Cu(bipy)(tsasnO)2].2H2O are investigated. The complex crystallizes in the space group P2(1)/n, with a = 12.502(2), b = 15.298(2), c = 18.901(8) angstrom, beta = 96.80(2)-degrees and Z = 4. The complex consists of discrete [Cu(bipy)(tsasnO)2] units and lattice water molecules. The Cu(II) ion is coordinated to two bipy nitrogens and two carboxylate oxygens from two aminoacidate anions in a square-planar geometry.

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

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.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. 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.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.

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. 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.

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.

I.M.Vezzosi; M.Saladini; L.P.Battaglia; A.Bonamartini Corradi ( 1985 ) - Crystal and molecular structure of p-propane-1,3-diamine di[bis(propane-1,3diamine)copper(II)perchlorate complex - INORGANICA CHIMICA ACTA - n. volume 100 - pp. da 261 a 266 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The title compound, [Cu2(1,3-pn)5](ClO4)4, crystallizes in the orthorhombic space group Pbca with Z = 8 formula units in a cell of dimensions: a = 30.88(9), b = 14.664(6), c = 15.737(6) Å. The structure was solved by the heavy-atom method and refined by least-squares calculations to R = 0.082 for 3156 counter data. It consists of discrete dinuclear [Cu2(1,3-pn)5]4+ cations and ClO4− anions. In the dinuclear cation two propane diamine molecules act as chelating to each copper atom in the basal plane; the fifth amine molecule in an extended form, with its nitrogen atoms located at the apices of two square-pyramides, bridges two copper atoms. Magnetic and spectroscopic data are also discussed.

I.M.Vezzosi; A.Benedetti; M.Saladini; L.P.Battaglia; A.Bonamartini Corradi ( 1985 ) - Crystal and molecular structure of tris(propane-1,3-diamine)nickel(II) dinitrate complexes - INORGANICA CHIMICA ACTA - n. volume 97 - pp. da 195 a 199 ISSN: 0020-1693 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The title compound, [Ni(1,3-pn)3](NO3)2, crystallizes in the orthorhombic space group Pbca with eight formula units in a cell of dimensions a = 17.146(8), b = 14.364(5) and c = 15.054(7). The structure was solved by the heavy-atom method and refined by least-squares calculations to R = 0.053 for 1439 counter data. It consists of discrete, slightly distorted octahedral [Ni(1,3-pn)3]2+ cations and NO3− anions. One of the three six-membered chelate rings show a pronounced flattening unusual chair conformation. Magnetic and spectroscopic data agree to a lower stability of six-membered chelate rings, compared to five-membered chelate ones.

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.

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; 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.

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.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.

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.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.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; 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

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.

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.