GIAN CARLO PELLACANI - personale UniMoRe

Nuova ricerca

GIAN CARLO PELLACANI

Professore emerito
Dipartimento di Ingegneria "Enzo Ferrari"

Pubblicazioni

- Procedimento di inertizzazione di amianti mediante applicazioni di microonde [Brevetto]
Leonelli, Cristina; Pellacani, Gian Carlo; Siligardi, Cristina; G., Gherardi; G., Marucci
abstract

Il brevetto descrive un metodo per poter riscaldare in un forno a microonde diverse pezzature di amianto o materiali contenenti amianto. Il riscaldamento a microonde, trasferendo energia sotto forma del campo elelttromagnetico, riesce a riscaldare in breve tempo l'amianto che è un noto isolante termico. A seguito del riscaldamento il minerale fibroso degrada in un materiale assolutamente innocuo attuando così l'auspicata inertizzazione ed azzerando la tossicità del prodotto iniziale. Il brevetto riporta dati sperimentali eseguiti presso i laboratori attrezzati dell'ENEA. Si riporta anche l'idea di avere applicatori aperti in grado di realizzare l'inertizzaizone su superfici piane di amianto o di materiali conteneti amianto, come ad esempio l'Eternit.

2009 - Alkali-ions diffusion, mullite formation, and crystals dissolution during sintering of porcelain bodies: Microstructural approach [Articolo su rivista]
Leonelli, C.; Kamseu, E.; Boccaccini, D. N.; Sglavo, V. M.; Pellacani, G. C.
abstract

The effect of alkali-silicate glassy matrix as replacement for feldspar in soft and hard porcelain compositions was studied. SEM and X-ray diffraction analysis were used to evidence phase evolution. For each composition, the influence of soaking time was evaluated. The difference in chemical composition (amount of alkali and alumina) between the two types of porcelain studied influenced the final microstructure: density, pore size and shape, and mullite content. Quartz dissolution was more important in soft porcelain where the mullitization was limited by the low amount of alumina compared to hard porcelain. Replacing the feldspar by alkali-silicate glassy matrices with similar chemical composition, the amount of secondary mullite and mechanical properties increased in both soft and hard compositions.

2009 - Descriptive microstructure and fracture surface observations of fired volcanic ash [Articolo su rivista]
Leonelli, C.; Kamseu, E.; Melo, U. C.; Corradi, A.; Pellacani, G. C.
abstract

Crystals of the pyroxene group (diopside, augite and enstatite, hedenbergite), series of crystals with the general formula (Mg x Fe1-x )2SiO4 having various geometry, identified as spinel (and olivine), and plagioclase crystals from anorthite to anorthoclase that grow together in mass having thin parallel groves embedded in a complex matrix together with calcium alumina silicate grains were found to be the descriptive microstructure of fired volcanic ash. Quartz grains were rarely present as confirmed by dilatometry analysis, XRD, SEM and DTA. The presence of dendrites continuously growing to pyroxene crystals indicated the precipitation/crystallization of these crystals from matrix and regions of glass concentration enhance by ions diffusion. Rings of Ti-rich iron micro-crystals observed around spinel (and olivine) suggested the probable nucleating role of these micro-crystals for the precipitation/crystallization phenomenon. The various types of crystals formed, the difference in their geometry and size and their interlocking mechanism result in a contiguous and dense structure with relevant characteristics at relative low temperature (1125-1150 °C) confirming volcanic ash as a promising alternative raw material for vitrified ceramic products. It was concluded that controlled precipitation/crystallization of raw volcanic ash results on microstructure similar to that of glass-ceramic materials. The observation of fracture surface allowed comparison of fracture mechanics of volcanic ash ceramic to that of conventional vitrified ceramics. © 2009 Springer Science+Business Media, LLC.

2009 - Descriptive microstructure and fracture surface observations of fired volcanic ash [Abstract in Atti di Convegno]
Leonelli, C.; Kamseu, E.; Melo, U. C.; Corradi, A.; Pellacani, G. C.
abstract

Crystals of the pyroxene group (diopside, augite and enstatite, hedenbergite), series of crystals with the general formula: (MgxFe1-x)2SiO4 having various geometry, identified as spinel (and olivine), and plagioclase crystals from anorthite to anorthoclase that grow together in mass having thin parallel groves embedded in a complex matrix together with calcium alumina silicate grains were found to be the descriptive microstructure of fired volcanic ash. Quartz grains were rarely present as confirmed by dilatometry analysis, XRD, SEM and DTA. The presence of dendrites continuously growing to pyroxene crystals indicated the precipitation/crystallization of these crystals from matrix and regions of glass concentration enhance by ions diffusion. Rings of Ti-rich iron micro-crystals observed around spinel (and olivine) suggested the probable nucleating role of these micro-crystals for the precipitation/crystallization phenomenon. The various type of crystals formed, the difference in their geometry and size and their interlocking mechanism results in a contiguous and dense structure with relevant characteristics at relative low temperature (1125-1150°C) confirm volcanic ash as promising alternative raw materials for vitrified ceramic products. It was concluded that controlled precipitation/crystallization of raw volcanic ash results on microstructure similar to that of glass-ceramic materials. The observation of fracture surface allowed comparison of fracture mechanics of volcanic ash ceramic to that of conventional vitrified ceramics. © 2009 Woodhead Publishing Limited.

2008 - Mullitization behaviour during thermal treatment of three kaolinitic clays from Cameroon: Densificaron, sintering kinetics and microstructure [Articolo su rivista]
Leonelli, C.; Kamseu, E.; Melo, U. C.; Corradi, A.; Pellacani, G. C.
abstract

Three kaolinitic clays from Cameroon were studied for their mullitization behaviour. The three clayey materials were from Ntamuka (TAN), Mayouom (MAY) and Wabane (WAB), all situated in the hills of western Cameroon. X-ray diffraction and thermal, dilatometric and SEM-EDS analyses were used to follow up the phase evolution, sintering kinetics and microstructure of the three materials as a function of temperature (1000-1500°C). Fine powders of each sample were pressed and treated in the above temperature range with the goal to correlate the phase evolution with densificaron parameters (shrinkage, porosity, density and mechanical strength). The nucleation of mullite and the increase of peak intensities were directly correlated to continuous densification and reduction of open porosity as observed under the SEM, The mullitization peak temperatures at 5°C/min were 973°C, 979.1°C, and 983.6°C respectively for TAN, MAY and WAB and - in the same order but at 20°C/min 992.1°C, 997.4°C and 1001.2°C. The mullitization phenomenon, which includes a first step of nucleation and a second of crystal growth, shows an activation energy that varies depending on the nature of sample investigated: the values ranged from 650 to 730 kJ/mol. The microstructure of the sintered products consisted on the elongated secondary mullite (types II and III) interlocking with primary (type I) mullite in a compact matrix with relative amount of glassy phase for MAY and WAB. The morphology of mullite grains in TAN was more different being laiger cuboid grains aggregated with cristobalite to form a compact microstructure. The formation of TiO2 crystals and then Ti-Al (tialite: Al2TiO5) crystals influenced the microstructure of MAY and WAB.

2008 - Nuovi vetri bioattivi contenenti zinco. [Relazione in Atti di Convegno]
Bertoldi, Carlo; Zaffe, Davide; Lusvardi, Gigliola; Pellacani, C.; Consolo, Ugo
abstract

Vedi allegato

2007 - Bending Strength and Elastic Modulus of Porcelain Compositions under Various Specimen Loading Configurations [Articolo su rivista]
Kamseu, Elie; Leonelli, Cristina; V. M., Sglavo; Boccaccini, Dino Norberto; Veronesi, Paolo; Pellacani, Gian Carlo; D., Njopwouoc
abstract

2007 - Characterisation of porcelain compositions using two china clays from Cameroon [Articolo su rivista]
Kamseu, Elie; Leonelli, Cristina; Boccaccini, Dino Norberto; Veronesi, Paolo; Miselli, Paola; Pellacani, Gian Carlo; U., CHINJE MELO
abstract

Mayouom and Ntamuka china clays, from Cameroon were used to produce porcelain bodies. Two soft porcelain formulations: PSI (withMayouom) and PSII (with Ntamuka) and one hard porcelain, PH (with both Mayouom and Ntamuka) were prepared.The maximum density and flexural resistance for these formulations were obtained at 1200 8C for PSI, 1225 8C for PSII and 1350 8C for PH.Their properties and values were, respectively, density (2.42, 2.58 and 2.59 g/cm3), water absorption (0.15, 0.15 and 0.02%), porosity (4.3, 5.3 and4.2%) and flexural strength (148, 148 and 160 MPa). In addition to varying amounts of liquid phase, the soft porcelain formulations containedmullite and quartz crystals while the hard porcelains contained quartz and more intense mullite peaks. At 1250 8C PSI and PSII presented a selfglazingphenomenon which gave significant brightness and high aesthetic quality. PH with lower alkali (especially Na+) did not self-glaze even at1400 8C. Considering the soft porcelain formulations, the higher amounts of TiO2 (0.83%) and Fe2O3 (0.31%) in PSI (with Mayoum clay) resultedin a higher sintering effect at lower temperatures, giving lower water absorption and higher resistance. Both Mayouom and Ntamuka china clayswere found to be suitable raw materials for the production of porcelain stoneware tiles. Ntamuka could also be used for the manufacture of optimalquality whitewares.

2007 - Determination of thermal shock resistance in refractory materials by ultrasonic pulse velocity measurement [Articolo su rivista]
D. N., Boccaccini; Romagnoli, Marcello; E., Kamseu; Veronesi, Paolo; Leonelli, Cristina; Pellacani, Gian Carlo
abstract

Thermal shock resistance of refractory materials is one of the most important parameters in refractory material characterization since it determines their performance in many applications. Ultrasonic pulse velocity testing was used for non-destructive quantification of thermal shock damage in refractory plates used as support for the firing of porcelain articles. When refractory materials are subjected to the industrial thermal cycles crack nucleation and propagation occurs resulting in loss of strength and material degradation. The formation of cracks decreases the velocity of ultrasonic pulses travelling in the refractory because it depends on the density and elastic properties of the material. Therefore measuring either of these properties can directly monitor the development of thermal shock damage level. Young's modulus of representative samples was calculated using measured values of ultrasonic velocities obtained by ultrasonic pulse velocity technique. Results were compared with industrial statistical data of thermal shock behaviour of the investigated materials. The capability of the ultrasonic velocity technique for simple, sensitive, and reliable non-destructive characterisation of thermal shock damage was demonstrated in this investigation. (c) 2006 Elsevier Ltd. All rights reserved.

2007 - Quality control and thermal shock damage characterization of high-temperature ceramics by ultrasonic pulse velocity testing [Articolo su rivista]
Boccaccini, Dino Norberto; Romagnoli, Marcello; Veronesi, Paolo; Cannio, Maria; Leonelli, Cristina; Pellacani, Gian Carlo; T. V., Husovic; A. R., Boccaccini
abstract

Ultrasonic pulse velocity testing was carried out to perform nondestructive quality control of refractory plates used as substrates in fast firing of porcelain whiteware. Two cordierite-mullite refractory compositions characterized by different microstructure morphologies and crack propagation behavior were investigated after a number of industrial thermal cycles. Ultrasonic velocity measurements were used to determine the presence of internal voids/cracks in the samples, originating from the manufacturing procedure. A brief discussion about the correlation between microstructure, crack propagation behavior, and thermal shock resistance is presented. Empirical models were developed to predict the service life of refractory plates from measured values of ultrasonic velocities on as-received samples.

2007 - Recycling of microwave inertised asbestos containing waste in refractory materials [Articolo su rivista]
Boccaccini, Dino Norberto; Leonelli, Cristina; Rivasi, Maria Rosa; Romagnoli, Marcello; Veronesi, Paolo; Pellacani, Gian Carlo; A. R., Boccaccini
abstract

Asbestos is a health hazard and its removal a priority for pollution prevention. Asbestos containing wastes (ACW) can be transformed into inert silicate phases by means of microwave irradiation. The aim of this investigation was to recycle microwave inertised ACW in mullite-cordierite refractory materials. A MgO-rich talc was replaced by inertised asbestos keeping approximately equal oxide composition of the raw materials. No significant variations of water absorption, linear shrinkage and Young's modulus but a higher occurrence of cordierite phase with the change of raw material was found. This can be considered an important technological result. (c) 2006 Elsevier Ltd. All rights reserved.

2007 - Thermal shock behavior of mullite-cordierite refractory materials [Articolo su rivista]
Boccaccini, Dino Norberto; Leonelli, Cristina; Romagnoli, Marcello; Pellacani, Gian Carlo; Veronesi, Paolo; I., Dlouhy; A. R., Boccaccini
abstract

The characterisation of thermal shock damage in cordierite–mullite refractory plates used as substrates in fast firing of porcelain whiteware has been investigated. Two different refractory compositions (termed REFO and CONC), characterised by different silica to alumina ratios, were studied. Thermal shock damage was induced in as received samples by water quenching tests from 1250degC. Thermal and mechanical properties were measured at room temperature by means of standard techniques and then the thermal shock resistance parameter R was calculated. The fracture toughness of selected samples was measured before and after thermal shock by the chevron notched specimen technique. The reliability of this technique for evaluation of small differences in fracture toughness after a given number of thermal shock cycles was investigated.The suitability of KIc measurements by the chevron notched specimen technique to characterise the development of thermal shock damage in refractory materials was proved in this investigation.

2006 - AMORPHOUS GERMANIUM (II) SULPHIDE PARTICLES OBTAINED BY MICROWAVE ASSISTED DECOMPOSITION OF GERMANIUM (IV) DISULFIDE [Articolo su rivista]
E., Bonometti; M., Castiglioni; P., MICHELIN LAUSAROT; Leonelli, Cristina; Bondioli, Federica; Pellacani, Gian Carlo; A. A., Barba
abstract

Microwave assisted decomposition of germanium(IV) sulphide has been used to obtain, by sublimation in He current, amorphous particles of germanium(II) sulphide in the 0.1-3.0 microns range. The adopted technique is reported in details as well as the full physical-chemical characterisation of the product (XRD, TEM, Raman, MS and dielectric properties).

2006 - Amorphous germanium(li) sulfide particles obtained by microwave assisted decomposition of germanium (IV) sulfide [Articolo su rivista]
Bonometti, E.; Castiglioni, M.; Lausarot, P. M.; Leonelli, C.; Bondioli, F.; Pellacani, G. C.; Barba, A. A.
abstract

The preparation of small, amorphous, and metastable Germanium sulfide GeS particles by using microwave assisted sublimation is discussed. The vitreous GeS2 is formed with the help of rapid quenching of liquid GeS 2. An equilibrium has also been used to calculate the standard molar enthalpy of the formation for GeS2 and for the chemical transport of Ge. The germanium sulfide was prepared using wet chemistry and characterized by its Raman spectrum for checking purity. The particle sizes observed in the experiment are smaller where the sublimation of GeS is carried in Air flow. The increase of the flow rate of the carrier gas leads to a more rapid removal of the particles from the hot subliming system preventing particles agglomeration. The transmission electron microscopy observations indicate the formation of spherical particles that have diameter in the 10-20 nm range.

2006 - MICROWAVE THERMAL INERTISATION OF ASBESTOS CONTAINING WASTE AND ITS RECYCLING IN TRADITIONAL CERAMICS [Articolo su rivista]
Leonelli, Cristina; Veronesi, Paolo; Boccaccini, Dino Norberto; Rivasi, Maria Rosa; Barbieri, Luisa; Andreola, Nora Maria; Lancellotti, Isabella; Rabitti, Daniela; Pellacani, Gian Carlo
abstract

Asbestos was widely used as a building material prior to the 1970´s. It is well known that asbestos is a health hazard and its progressive elimination is a priority for pollution prevention. Asbestos can be transformed to non-hazardous silicate phases by microwave thermal treatment. The aim of this investigation is to describe the microwave inertization process of asbestos containing waste (ACW) and its recycling in porcelain stoneware tiles, porous single-fired wall tiles and ceramic bricks following industrial manufacture procedure. Inertised asbestos powder was added in the percentages of 1, 3, and 5 wt.% to commercially available compositions and then fired following industrial thermal cycles. Water absorption and linear shrinkage of the obtained industrial products do not present significant variations with additions up to 5 wt.% of microwave inertised ACW.

2006 - Microwave and conventional hydrothermal synthesis of zirconia doped powders [Relazione in Atti di Convegno]
Bondioli, F.; Leonelli, C.; Siligardi, C.; Pellacani, G. C.; Komarneni, S.
abstract

Hydrothermal synthesis of powders is a very attractive process to directly prepare submicrometer- and nanometer-sized crystalline powders because of reduced contamination and low synthesis temperature. The application of microwave radiation during the process enhances the reaction kinetics by 1-2 orders of magnitude. Nanosized Pr-doped zirconium oxide powders were prepared by adding NaOH to a zirconyl chloride aqueous solution under microwave- hydrothermal conditions. The properties of the powders produced are compared with those of powders obtained by conventional hydrothermal synthesis. © Springer-Verlag Berlin Heidelberg 2006.

2005 - REFRACTORIES CONTAINING INERTISED ASBESTOS AS RAW MATERIAL [Articolo su rivista]
Leonelli, Cristina; Boccaccini, Dino Norberto; Rivasi, Maria Rosa; Romagnoli, Marcello; Veronesi, Paolo; Pellacani, Gian Carlo; A. R., Boccaccini
abstract

It is well known that asbestos is a health hazard and its progressive elimination is a priority for pollution prevention. Asbestos can be transformed into non hazardous silicate phases by means of thermal treatments. This investigation describes the recycling of microwave inertised asbestos in refractory materials of both alumina-mullite and mullite-cordierite compositions. The increase of cordierite content found in samples containing inertised asbestos should lead to an improvement in thermal shock behaviour of the refractory materials. In the case of mullite-cordierite refractories, it was found that inertised asbestos can be used as raw material to replace the currently used MgO-rich talc. No significant variation of the Young’s modulus of samples made with inertised asbestos compared to the commercial based composition was found, indicating that inertised asbestos containing refractories should behave similarly to commercial refractory materials in terms of mechanical properties.

2004 - Microwave assisted burn-out of organic compounds in ceramic systems [Relazione in Atti di Convegno]
Leonelli, Cristina; Pellacani, Gian Carlo; Siligardi, Cristina; Veronesi, Paolo
abstract

Ceramic materials containing organic compounds, as a result of a manufacturing process or coming from an unwanted pollution, can be efficiently beat-treated using microwaves rapid, volumetric and selective heating. Electromagnetic field modelling of microwave-matter interactions inside the microwave applicator helped choosing the best experimental conditions, leading to fast cycles and to the maximisation of energy transfer from the microwave source to the load. The debinding process of Al2O3, ZrO2 and TiO2 components and the complete recovery of Al2O3 millimetric spheres has been performed by microwave heating, allowing a drastic manufacturing time reduction. Microwaves, proved to be a powerful tool to speed up the hear treatment of the aforementioned ceramic systems containing significant percentages of organic compounds, which present a strong and preferential coupling to microwaves at low temperature.

2004 - The electromagnetic field modelling as a tool in the microwave heating feasibility studies [Articolo su rivista]
Veronesi, Paolo; Leonelli, Cristina; Rivasi, Maria Rosa; Pellacani, Gian Carlo
abstract

The electromagnetic field modeling of a loaded microwaveapplicator can help in choosing the proper conditions tosuccessfully organize feasibility studies, allowing savings oftime and money, which are usually wasted during “blindfold”tests. As a matter of fact, when microwave heating of materialsis performed, the pronounced nonhomogeneity of the fielddistribution in multi-mode applicators can produce contradictoryexperimental results, leading to erroneous conclusions regardingthe main variables controlling the process. This is particularlytrue considering the microwave heat treatment of low thermalconductivity materials. Two different applications in the ceramicfield, comparing the results of “blindfold” and modeling-aidedexperimental conditions, are presented: de-binding of technicalceramics and asbestos inertization and/or vitrification. Thanksto a better knowledge of the electromagnetic field in theapplicators, it has been possible to succeed in applicationsthat, at a first glance, did not seem promising at all.

2003 - Comparison of various solvent media efficiency in the grinding of a frit containing zirconium oxide [Articolo su rivista]
Andreola, Nora Maria; Mc, D'Arrigo; Leonelli, Cristina; Siligardi, Cristina; Pellacani, Gian Carlo
abstract

In the present work thermal and chemical properties of a glass-ceramic frit containing zirconium oxide are evaluated after milling in various polar and nonpolar solvents. Particle-size distribution is one of the main variables investigated to evaluate the efficiency of several solvents. Milling in various solvents does not affect the thermal properties of the glass while the presence of polar groups in the solvent molecule increases the cation release from the glass.

2003 - Effect of V2O5 addition on the crystallisation of glasses belonging to the CaO-ZrO2-SiO2 system [Articolo su rivista]
Ferrari, Anna Maria; Leonelli, Cristina; Pellacani, Gian Carlo; Siligardi, Cristina
abstract

The crystallisation of CaO-ZrO2-SiO2 glasses doped with V2O5 (0.1-5 mol%) has been investigated in terms of microstructure and thermal parameters. Results indicate that crystallisation is predominantly controlled by a surface nucleation mechanism, even though a partial bulk nucleation has been encountered in compositions containing more than 2 mol% of doping oxide. As detected from differential thermal analysis curves, glass transition temperature and crystallisation temperature, are strongly dependent upon V2O5 content varying from 0.0 to 2.0 mol%, while the crystallisation activation energy values decrease with a parabolic trend from B-glass (0.0 mol% V2O5 content, 495 +/- 7) to V-0.7 (0.7 mol% V2O5 content, 420 +/- 6) composition, increasing again to 442 +/- 5 kJ/mol K with higher amount of V2O5. The microstructure of the glass-ceramic materials clearly showed a marked dependence upon the amount of V2O5, also due to the presence of phase separation for content higher than 0.7 mol%. Wollastonite, CaO . SiO2 and a calcia-zirconia-silicate, 2CaO . 4SiO(2) . ZrO2, are the main crystalline phases whose ratio slightly varies with vanadium oxide content. The glass ceramics obtained from the studied materials are greenish and bluish coloured, so it is possible to use the studied glasses as coloured frits for tile glazes. (C) 2003 Elsevier Science B.V. All rights reserved.

2003 - In vitro bioactivity testing of ZrO2 nanopowders prepared by MW-assisted hydrothermal synthesis [Capitolo/Saggio]
Bondioli, Federica; Braccini, Silvia; Leonelli, Cristina; Pellacani, Gian Carlo; Lusvardi, Gigliola; Malavasi, Gianluca
abstract

Zirconia nanopowders obtaneid by hydrothermal synthesis were tested in vitro at 60°C for 30 days.Elemental analysis,XRD,SEM,TEM techniques were used for this study.Crystallinity and phase identification was performed before and after in vitro test

2003 - Numerical modelling of the fracture behaviour of a glass matrix composite reinforced with alumina platelets [Articolo su rivista]
Cannillo, Valeria; Pellacani, Gian Carlo; Leonelli, Cristina; Ar, Boccaccini
abstract

In this work the fracture behaviour of a composite material constituted by a borosilicate glass matrix reinforced with Al2O3 platelets is studied by means of a numerical model. This material, which was experimentally investigated in a previous paper, is characterised by the presence of thermal residual stresses that arise upon cooling from the processing temperature due to the thermal expansion coefficients mismatch between the matrix and the reinforcements. A numerical model based on finite element simulations of realistic composite microstructures was adopted for the present material. The crack propagation was studied using finite elements coupled with selected failure criteria (Griffith and Weibull approaches) implemented inside the elements. Computational determination of crack propagation during failure is compared with previously obtained experimental data and microscopy images of platelet-crack interactions, showing that the model provides results in good agreement with the experimental observations. (C) 2002 Elsevier Science Ltd. All rights reserved.

2003 - Sintering and crystallization behaviour of glass frits made from silicate wastes [Articolo su rivista]
Barbieri, Luisa; Corradi, Anna; Lancellotti, Isabella; Pellacani, Gian Carlo; A. R., Boccaccini
abstract

Sintering and crystallisation of glass powders obtained front vitrified silicate residues are investigated. The residues considered were ashes derived from the combustion of municipal wastes, glass cullet and feldspar waste, which were mixed in different proportions to result in SiO2 contents >46 wt%. By means of shrinkage measurements using heating microscopy, sintering was found to start at about 750degreesC for all mixtures investigated and to be completed in a very short temperature interval of between 100 and 150degreesC, depending on the composition. Crystallisation took place during the final sintering stage. By means of particle size analysis, linear shrinkage, water absorption and density measurements coupled with x-ray diffraction analysis and scanning electron microscopy, it was found that dense glass ceramic materials can be obtained from powders of average particle size <45 mum. The incinerator fly ash appears to be more suitable than incinerator grate ash for obtaining dense glass ceramics by the powder route developed here.

2003 - Substitution of boron for silicon in K-fluor-richterite glass ceramics [Articolo su rivista]
Hamzawy, Ema; Leonelli, Cristina; Pellacani, Gian Carlo
abstract

Substitution of B3+ for Si4+ in the K-fluor-richterite KNaCaMg5Si8O22F2 structure is presented through study of the crystallisation behaviour of glasses containing up to 36-55 wt% B2O3 (B/Si=4.00 at%) upon different heat treatment regimes. Gradual additions of boron lower the melting temperatures and strong v affect nucleation and crystallisation temperatures. The effect of boron replacement on the type of crystallising phases was manifested by DTA, XRD and EDAX. A single K-fluor-richterite fluor phase resulted in crystallisation of glasses with 17.34 wt% B2O3 (B/Si=0.80 at%). For greater boron contents (>4B per formula unit), borate mineral phase crystallised, namely suanite Mg2B2O5 in addition to fluorite CaF2 and fluorphlogopite KMg2.5Si4O10F2. In the case of maximum substitution (8B per formula unit, i.e. B/Si=4.00 at%) suanite becomes the main phase, K-fluor-richterite disappears, with fluorphlogopite in addition to fluorite. Incorporation of boron in the crystalline K-fluor-richterite changes the unit cell parameters. In comparison with the pre-reported unit cell constant of B free K-fluor-richterite relative decrease in the a, b and c axes with increase the P angle are detected in B containing K-fluor-richterite. A gradual increase in crystal growth rate takes place in the monoclinic K-fluor-richterite phase with increasing boron content. The boron rich sample shows microstructures of interlocked fluormica flakes.

2003 - Unique microstructure of glass-metal composites obtained by microwave assisted heat-treatments [Articolo su rivista]
Veronesi, Paolo; Leonelli, Cristina; Pellacani, Gian Carlo; Ar, Boccaccini
abstract

The present study deals with the computer-aided simulation of the microwave heating of metal/glass composites in single mode applicator and the rapid densification of borosilicate glass matrix composites containing molybdenum particle inclusions. The selective and penetrating microwave heating led to a layered porous structure of the samples. They consisted of a highly porous core containing spherical pores and a relatively dense outer shell. Pores in the central region were formed in the molten glass phase due to gas evolution and entrapment. The outer region of the sample remained at lower temperature and it sintered by viscous flow with minimal distortion.

2002 - CORRELATION BETWEEN STRUCTURE AND PROPERTIES IN NEW GLASSES CONTAINING ZrO2 [Articolo su rivista]
Lancellotti, Isabella; Leonelli, Cristina; Montorsi, Monia; Pellacani, Gian Carlo; Siligardi, Cristina; C., Meneghini
abstract

In this work several complementary techniques have been employed to carefully characterise the structure of CaO–ZrO2–SiO2 glasses as a function of Zr content. The research started from the basic binary system 40CaO.60SiO2 (wt%) to which 5, 10, 15 and 20 wt% ZrO2 has been added.Chemical and physical characterisation has been performed using classical techniques such as thermal analyses (differential thermal analysis and dilatometery) and water chemical resistance. Deeper insight on the intimate structure of the glasses has been achieved through molecular dynamics simulations and x-ray absorption spectroscopy. All results have been combined in order to accurately describe the role played by the different oxides in determining the properties of the glass. Particular carehas been devoted to the role of zirconia.

2002 - GLASS FORMATION AND DEVITRIFICATION IN THE K2O-ZRO2-SIO2 SYSTEM [Articolo su rivista]
Barbieri, Luisa; Lancellotti, Isabella; Leonelli, Cristina; Pellacani, Gian Carlo; Siligardi, Cristina
abstract

The influence of the introduction of ZrO2 up to 5 mol% into a 30K2O-70SiO2 base glass composition has been investigated with the aid of differential thermal analysis (DTA), FT-IR spectroscopy, as well as chemical durability tests (pH, conductivity and AES-Inductively Coupled Plasma measurements) and refraction index determination. Several differences have been carried out by comparison with similar compositions belonging to the Li2O-ZrO2-SiO2 system. The higher ionic radius and the lower field strength of K+ with respect to Li+ are responsible for higher stability towards crystallisation and lower chemical durability. Moreover, even though Zr4+ increases glass polymerisation (higher glass transition temperature, chemical durability and refraction index), the presence of high water content as highlighted by spectroscopy measurements, seams to weaken glass structure.

2002 - Glass formation and devitrification in the K2O-ZrO2-SiO2 system [Articolo su rivista]
Barbieri, Luisa; Corradi, Anna; Lancellotti, Isabella; Leonelli, Cristina; Siligardi, Cristina; C., Tomasi; P., Mustarelli; Pellacani, Gian Carlo
abstract

2002 - Microwave and conventional hydrothermal synthesis of zirconia doped powders [Abstract in Atti di Convegno]
Bondioli, Federica; Leonelli, Cristina; Siligardi, Cristina; Pellacani, Gian Carlo; S., Komarneni
abstract

Hydrothermal synthesis of powders is a very attractive process to directly prepare submicrometer- and nanometer-sized crystalline powders because of reduced contamination and low synthesis temperature. The application of microwave radiation during the process enhances the reaction kinetics by 1-2 orders of magnitude. Nanosized Pr-doped zirconium oxide powders were prepared by adding NaOH to a zirconyl chloride aqueous solution under microwave-hydrothermal conditions. The properties of the powders produced are compared with those of powders obtained by conventional hydrothermal synthesis

2002 - Microwave assisited sintering of powder mixtures of glass and tungsten particles [Articolo su rivista]
Veronesi, Paolo; Leonelli, Cristina; Pellacani, Gian Carlo; V., Fiumara; Aa, Barba; M., D'Amore
abstract

In this paper, the microwave assisted sintering behaviour of mixtures of glass microspheres and tungsten particles having a diameter in the range of the metal's skin depth at 2.45 GHz is investigated. The microstructure of the sintered samples is discussed as far as dielectric properties of the powders, heating rate and maximum sintering temperature are concerned.

2002 - Microwave technology applications in the synthesis of ceramic pigments [Relazione in Atti di Convegno]
Pellacani, Gian Carlo; Bondioli, Federica; Leonelli, Cristina; Siligardi, Cristina; Veronesi, Paolo; Manfredini, Tiziano
abstract

Long before chemists began altering this word, humans were interested in coloring their painting and their bodies as well as any objects they happened to make. Color is an economical way of creating new intereste in an existing product and is also the mosti immediately noticeable and least-expensive element in decoration. Thus, color is a primary tool in product development and marketing, especially in the ceramic tile industry, where product always becomes part of a general color scheme. This word resumes the experimental word done in the last few years by the CerMIC (Ceramic Investigation Center) at the University of Modena (Italy) regarding the application of the microwave technology to the synthesis of inorganic pigments. The choice has been done trying to reproduce in MW some of the most diffused and interesting crystalline structures capable of inducing coloration in ceramic tile body and coating, that is to say capable of thermal and chemical stability in the glazes or in the body at temperatures as high as 1250 degreesC for short period of times, (5-10 min), in order to evaluated the possible benefic effects of microwave heating treatments in this field.

2001 - Binary and ternary mixtures of deflocculant additives for whiteware slurries [Relazione in Atti di Convegno]
Andreola, F.; Pellacani, G. C.; Romagnoli, M.
abstract

In the traditional ceramic field, during the wet grinding stage liquid mixtures of additives are commonly used to guarantee high solids content (65-72 wt%) and a viscosity low enough to allow the suspension's workability. These characteristics are indispensable for using the new technologies for wet grinding (cylindrical and conical continuous mills) that require only 3-4 h of milling and permit considerable productivity (20 t/h). This work reports a laboratory study on the rheological behavior of whiteware slurries added with binary and ternary deflocculant mixtures.

2001 - Binary and ternary mixtures of deflocculating additives for whitewares slurries. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello; Pellacani, Gian Carlo
abstract

In the traditional ceramic field, during the wet grinding stage liquid mixtures of additives are commonly used to guarantee high so/ids content (65–72 wt%) and a viscosity low enough to allow the suspension's workability. These characteristics are indispensable for using the new technologies for wet grinding (cylindrical and conical continuous mills) that require only 3–4 h of milling and permit considerable productivity (20 t/h). This work reports a laboratory study on the rheological behavior of whiteware slurries added with binary and ternary deflocculant mixtures.

2001 - Enhancing the mechanical properties of porcelain stoneware tiles: a microstructural approach [Articolo su rivista]
Leonelli, C.; Bondioli, F.; Veronesi, Paolo; Romagnoli, Marcello; Manfredini, Tiziano; Pellacani, Gian Carlo; Cannillo, Valeria
abstract

This paper focuses on the complexities of the microstructure and phase development in porcelain stoneware tiles produced following industrial fast single firing cycles. A microstructural investigation was conducted to determine if the addition of selected low cost minerals would improve mechanical properties. The minerals tested were quartz, mullite and kyanite. Uniaxially pressed samples were submitted to the same industrial firing schedule and tested according to the European tile standards before further microstructural analysis. All the requirements specified in UNI EN normative concerning BIa class tiles were fulfilled; moreover, mullite and kyanite added formulations showed sensible increases in mechanical properties, especially as far as flexural strength and abrasion resistance are concerned.

2001 - Nucleation and crystallization of new glasses from fly ash originating from thermal power plants [Articolo su rivista]
Barbieri, Luisa; Lancellotti, Isabella; Manfredini, Tiziano; Pellacani, Gian Carlo; Jm, Rincon; M., Romero
abstract

The nucleation and crystallization kinetics of new glasses obtained by melting mixtures of a Spanish carbon fly ash with glass cullet and dolomite stag at 1500 degreesC has been evaluated by a calculation method. These glasses, whose microstructure was examined by TEM carbon replica, were susceptible to controlled crystallization in the 800 degrees -1100 degreesC range. The resulting glass-ceramics developed acicular and branched wollastonite crystals or a network of dendritic pyroxene mixed with anorthite feldspar (SEM and EDX analysis). The time-temperature-transformation curves (processing of the XRD data) showed the crystallization kinetics and the critical cooling rate to be in the 12 degrees -42 degreesC/min range.

2001 - Porcelain stoneware as a composite material: identification of strengthening and toughnening mechanisms [Articolo su rivista]
Leonelli, Cristina; Veronesi, Paolo; Cannillo, Valeria; Pellacani, Gian Carlo; A. R., Boccaccini
abstract

Porcelain stoneware is studied using the principles usually applied for composite materials

2001 - Qualitative experimental study of the electromagnetic field distribution in microwave multimode cavities [Articolo su rivista]
Lusvarghi, L.; Pellacani, G. C.; Rivasi, M. R.
abstract

The most common applicator for the microwave treatment of materials is a multimode cavity. Because of its own experimental geometry, the electromagnetic field inside this kind of oven is usually extremely unhomogeneous, in this work, the energy distribution has been qualitatively studied investigating the thermal effect caused by the coupling of the field with a dielectric and detected by a white thermal paper, which gradually blackens when reaching temperature around 100-150 °C. We proved that the spatial behaviour of the microwave filed inside the cavity depends strongly on the kind of load, i.e. the sample to be treated, its size and position (x, y, z) in the applicator and the presence or absence of metallic devices, such as a mode stirrer or a thermocouple to measure the sample temperature.

2001 - Synthesis of oxide pigments powders by microwave treatments [Relazione in Atti di Convegno]
Corradi, Anna; Leonelli, Cristina; Bondioli, Federica; Siligardi, Cristina; Veronesi, Paolo; Pellacani, Gian Carlo
abstract

In this paper the authors report the use of microwave technology to synthesize inorganic pigment to color traditional ceramic material

2000 - Bulk crystallization of glasses belonging to the calcia-zirconia-silica system by microwave energy [Articolo su rivista]
Siligardi, Cristina; Mc, D'Arrigo; Leonelli, Cristina; Pellacani, Gian Carlo; Te, Cross
abstract

This paper reports results that show the effect of microwave absorption on the bulk crystallization of two glasses in the CaO-ZrO2SiO2 system. The glass samples were de vitrified using either microwave or conventional heating, to compare the results obtained from the two different techniques. Remarkably different crystallization paths were observed, depending mostly on the composition of the glass. This observation was especially true when microwave heating was used, where the dielectric losses observed in silicate glasses are related to the ZrO2 content. X-ray diffraction analysis was performed on the powdered samples, to determine the crystalline phases present. The microstructure and microanalysis results of these glass-ceramic compositions are presented and are related to the different ZrO2 contents.

2000 - Crystallisation kinetics of a 2·3Li2O. 1·1ZrO2.6·6SiO2 glass [Articolo su rivista]
Novaes de Oliveira, A. P.; Alarcon, O. E.; Manfredini, T.; Pellacani, G. C.; Siligardi, C.
abstract

The nucleation and growth of zircon (ZrSiO4) crystals on the free surface of a 2·3Li2O.1·1ZrO2.6·6 SiO2 glass was investigated through differential thermal analysis (DTA), x-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystallisation was completed at about 860°C with an activation energy value corresponding to 740 kJmol-1. Samples with polished free surfaces were nucleated at selected temperatures in the range 640-690°C and then heated at 750°C for 30 rain for crystal growth. A dominant effect of surface nucleation was observed and the number of ZrSiO4 crystals per unit area and the mechanism of crystallisation were determined. It was concluded that the nucleation starts from a fixed number of surface nuclei which reach a maximum at 670°C corresponding to a zircon crystal number density of 1·33×1011 m-2 and that at 880°C a uniform surface crystalline layer was formed with a rate of growth of 1·93 μm min-1.

2000 - Densification of glass powders belonging to the CaO-ZrO2-SiO2 system by microwave heating [Articolo su rivista]
Siligardi, Cristina; Leonelli, Cristina; F., Bondioli; Corradi, Anna; Pellacani, Gian Carlo
abstract

Densification and microstructural changes of two glassy compositions belonging to the wollastonite and zirconia stability fields in the ternary CaO-ZrO2-SiO2 system were studied in a 2.45 GHz multimode microwave cavity. The effect of microwaves is to lower the sintering and devitrification temperature with stronger influence for high zirconia content composition. Correlation was found between dielectric properties and heating rate, showing lower interaction temperature for high zirconia content composition which starts to absorb microwave energy at about 400 degrees C compared to 800 degrees C for the low-zirconia one. Sintering and crystallization processes evolved in complex ways during heat treatment so that the two final glass-ceramic materials exhibit different microstructures, crystalline phases and mechanical properties. (C) 2000 Elsevier Science Ltd. All rights reserved.

2000 - Effect of silicon carbide whisker reinforcement on the CaO-ZrO2-SiO2 glass-ceramic system [Articolo su rivista]
Barbieri, Luisa; M. C., D’Arrigo; Leonelli, Cristina; Siligardi, Cristina; Pellacani, Gian Carlo; C. C., Sorrell; M., Hoffman; S., Moricca
abstract

An industrial frit formulated in the new CaO-ZrO2--SiO2 glass-ceramic system was studied as a matrix for whisker reinforced composites. The frit was ball milled in acetone and wt ultrasonically mixed with 5, 10, 20 and 30 vol.-% SiC whiskers in order to overcome whisker agglomeration and obtain intimate mixing of the two phases. The samples were hot pressed at 14 MPa in graphite dies, using a N-2 atmosphere, for 2 h at 1280 degreesC. In order to investigate the effect of whiskers as a reinforcement, flexural strength as well as crack configuration and propagation were taken into consideration. Whisker orientation perpendicular to the hot pressing direction was found by SEM observation, and no carbon layer at the whisker/matrix interface was detected by EPMA. Further characterisation of the specimens involved physical (density, elastic modulus) and microstructural properties (XRD, SEM, TEM). The result of glass devitrification was inter-locked wollastonite crystals. BCT/436.

2000 - Molecular dynamics simulations of alumina addition in sodium silicate glasses [Articolo su rivista]
Montorsi, Monia; Menziani, Maria Cristina; Leonelli, Cristina; Pellacani, Gian Carlo; A. N., Cormack
abstract

Molecular dynamics simulations of alumina containing silicate glasses have been performed in order to determine the influence of that ion on the final properties of the glasses. In particular, short- and mid-range structures were analyzed in terms of the distribution of non bridging oxygen, bridging oxygen, three bridging oxygen species in the glasses, along with the coordination number distribution (cn) and qn species distribution. The results support the hypothesis that the observed changes in the property of the glasses could be directly related to the coordination preferences of the Al ion.

2000 - The influence of additives on the rheological behavior of acqueous concentrated glaze suspensions. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello; Pellacani, Gian Carlo
abstract

Influenza di alcuni additivi chimici sul comportamento reologico di sospensioni di fritte ceramiche.

2000 - Transparent glass-ceramics obtained during cooling [Articolo su rivista]
Siligardi, Cristina; Leonelli, Cristina; Pellacani, Gian Carlo; Wc, Lacourse; P., Mustarelli; C., Tomasi
abstract

This paper examines the microstructure of glass-ceramics obtained during cooling melts of different compositions in the ternary Li2O-Al2O3-SiO2 system. The effects of MgO, ZnO, and TiO2 additions revealed necessary to attain the crystallisation during cooling. The microstructure of the transparent glass-ceramics, once obtained with a 15-min soak in the temperature range of 700-800 degreesC, is stable at room temperature. An interesting colour change has been noted during the treatment and TEM investigations confirmed that such coloration is produced by phase separation. The crystalline phase evolved are mixed titanates of Mg and Zn which develop from the phase separated glass, soon after T-g, and grow to form the nucleation centres for other crystalline phases. The evolution from phase separated glass to glass-ceramic has been followed by modulated DSC and NMR spectroscopies.

1999 - Influence of some transition metal cations on the properties of BaO-containing glasses and glass-ceramics [Articolo su rivista]
Barbieri, Luisa; S., Bruni; F., Cariati; Leonelli, Cristina; Pellacani, Gian Carlo; Siligardi, Cristina; U., Russo
abstract

Copper, iron, and manganese oxides were added separately to melts of BaO-MgO-Al2O3-SiO2 glasses up to a maximum of 5 mol%, than devetrified at 100 degrees C for 1 h. The transition cations acted as fluxes on the glass properties by reducing the temperature of glass transition and the exothermic crystallization peak temperature. The activation energy for crystallization was slightly reduced, remaining in the feldspatic phase range. The effects on other properties, such as hardness and toughness, were evaluated in terms of indentation tests and related toation field strength and heating treatment. The presence of copper and manganese oxides inhibited the formation of hexacelsian crystals in the glass-ceramics, thus avoiding dangerous dimensional stress due to phase transformation. The complex evolution of the remaining crystalline phases is discussed in light of XRD, FT-IR, and SEM observations.

1999 - Inorganic pigments for ceramic tiles: Characteristics and industrial applications [Articolo su rivista]
Bondioli, F.; Manfredini, T.; Pellacani, G. C.
abstract

This paper aims at presenting an overview of recent trends in the industrial applications of inorganic pigments in the tile industry. Examples of applications of natural and synthetic inorganic pigments to colour-glazed and unglazed tiles at high temperatures are presented. The most important aspects concerning the physical and chemical properties of pigments, the design of new pigments and application of unconventional synthesis methods are discussed.

1999 - Structural and electrical characterization of polymeric haloplumbate(II) systems [Articolo su rivista]
Corradi, Anna; Ferrari, Anna Maria; Pellacani, Gian Carlo; A., Saccani; F., Sandrolini; P., Sgarabotto
abstract

The synthesis and the structural, thermal, and electrical characterization of haloplumbate(II) systems are described. The counterions are diprotonated Linear aliphatic amines, such as the 2-methylpentane-1,5-diamine (2meptH(2)) and propane-1,3-diamine (pnH(2)) dications. The (2meptH(2))[PbCl4] and (2meptH(2))[PbBr4] are isostructural, space group Cc, with a = 24.140(4) Angstrom, b = 7.720(2) Angstrom, c = 7.795(2) Angstrom, beta = 98.1(1)degrees, Z = 4 for the chlorine compound and a = 24.539(4) Angstrom, b = 8.031(2) Angstrom, c = 8.198(2) Angstrom, beta = 99.6(1)degrees, Z = 4 for the bromine compound; the (2meptH(2))[Pb1.5I5] crystallizes in the triclinic P (1) over bar space group, with a = 11.803(3) Angstrom, b = 12.565(3) Angstrom, c = 8.494(8) Angstrom, alpha = 106.2(1)degrees, beta = 100.5(1)degrees, gamma = 117.4(1)degrees, Z = 2; the crystals of (pnH(2))[PbCl4] are orthorhombic, space group P2(1)2(1)2(1), a = 19.247(4) Angstrom, b = 7.862(2) Angstrom, c = 7.581(2) Angstrom, Z = 4; the (pnH(2))(2)[Pb1.5Br7]. H2O crystallizes in the triclinic P (1) over bar space group, with a = 11.517(3) Angstrom, b = 14.122(3) Angstrom, c = 8.149(2) Angstrom, alpha = 104.1(1)degrees, beta = 109.8(1)degrees, gamma = 77.5(1)degrees, Z = 2. Three different types of polymeric haloplumbate(II) systems were obtained: strictly monodimensional, (2meptH(2))[Pb1.5I5], ribbonlike, (pnH(2))(2)[Pb1.5Br7]. H2O, and perovskite-like structures, (pnH(2))[PbCl4] and (2meptH(2))[PbX4] (X = Cl, Br). Worthy of note is the presence of organic dications in their extended form, intercalated between the inorganic anions, which are at different distances, depending on the amine length. The nitrogen atoms of the ammonium cations interact with the inorganic anions forming a network of hydrogen bonds, which contribute to the crystal packing.

1998 - Characterisation of the surface conductivity of glassy materials by means of impedance spectroscopy measurements [Articolo su rivista]
Fontanesi, C.; Leonelli, C.; Manfredini, T.; Siligardi, C.; Pellacani, G. C.
abstract

Abstract The phenomenon of tin dioxide doping by antimony, Sb(V), atoms in semiconductive glazes is discussed. In particular, the impedance spectra of the glaze surface at room temperature were experimentally determined, and the results were analysed in terms of equivalent circuits. The parameters resulting from the fitting procedure were related to the SnO2/Sb(V) relative content, the SnO2/Sb (V) percentage in the glaze, and the microstructure as observed by SEM. It is proposed that the addition of SnO2 and Sb2O3 to a common glaze for ceramic tile results in a semiconductive continuous phase, whose electrical characteristics fulfil the antistatic floor regulation, as far as surface conductivity is concerned. As a whole the obtained results suggest that the thermal cycle used in fast firing technology is capable to promote the oxidation of Sb2O3 to Sb2O4, resulting in a sufficient amount of Sb(V) capable of generating a semiconductive behaviour of the SnO2 crystalline phase dispersed in the glaze. © 1998 Elsevier Science Limited. All rights reserved.

1998 - Colouring effects of synthetic inorganic cobalt-pigments in fast-fired porcelainized stoneware tiles [Articolo su rivista]
Ferrari, Anna Maria; Leonelli, Cristina; Manfredini, Tiziano; Miselli, P; Monari, G; Pellacani, Gian Carlo
abstract

The paper reports a laboratory and industrial study on the rationalization of using synthetic cobalt oxide, aluminate and silicate pigments (0.5-4.0 wt%) for colouring porcelainized stoneware tiles. The addition of pigments to the base body in amounts up to about 1-2 wt% does not appreciably modify microstructure, nature and amount of phases of the fired tiles; while higher amounts, promoting liquid-phase formation, favour the sintering and can cause swelling of compact samples. On the basis of the results, inorganic cobalt-pigments seem very appropriate to produce coloured porcelainized stoneware tiles, but the better results are obtained by using CoO.AI(2)O(3). By controlling type and amount of pigment, it is possible to tailor different blue shades conferring to the product particularly interesting aesthetic effects.

1998 - Kinetic study of conventional solid-state synthesis of BaTiO3 by in situ HT-XRD [Relazione in Atti di Convegno]
Bondioli, Federica; Corradi, Anna; Ferrari, Anna Maria; Manfredini, Tiziano; Pellacani, Gian Carlo
abstract

The reaction path for the solid state synthesis of barium titanate, from barium carbonate and anatase, was first identified. In this work, plots of f(alpha) versus time, where alpha is the reacted fraction, were used to distinguish the reaction mechanisms of BaTiO3 formation by using an KT-XRD (high temperature x-ray diffraction) technique. On the basis of kinetic analysis, an overall process with two distinct regimes was proposed: for the first regime nucleation and growth are the dominant processes, while diffusion controls the second one. The reaction rates of both the processes were also determined.

1998 - Microwave-hydrothermal synthesis of nanophase ferrites [Articolo su rivista]
S., Komarneni; Mc, D'Arrigo; Leonelli, Cristina; Pellacani, Gian Carlo; H., Katsuki
abstract

This paper reports the synthesis of technologically important ferrites such as ZnFe2O4, NiFe2O4, MnFe2O4, and CoFe2O4 by using novel microwave-hydrothermal processing. Nanophase ferrites with high surface areas, in the range of 72-247 m(2)/g, have been synthesized in a matter of a few minutes at temperatures as low as 164 degrees C. The rapid synthesis of nanophase ferrites via an acceleration of reaction rates under microwave-hydrothermal conditions is expected to lead to energy savings.

1998 - Organic-inorganic composite materials: structural archetypes of linear polymeric chlorocadmates(II) [Articolo su rivista]
Corradi, Anna; Ferrari, Anna Maria; Pellacani, Gian Carlo
abstract

Structural considerations on the monodimensional polymeric chlorocadmates(II) are reported and two types of structural arrangement are recognized. truly monodimensional linear structures and polymeric endless ribbons. Regarding the linear structures, the hydrogen bonding capability of the cations is considered to favour the presence of the terminal chlorine ions on the inorganic chains and is therefore responsible for their structural motifs. The ribbon structures are favoured by particular concurrent conditions such as the weak hydrogen bending capability and opportune size dimensions of the cations. The Cd-Cl and Cd ... Cd distances in the different structural archetypes have been discussed and a graphical representation illustrating the stacking patterns of halocadmates is reported. (C) 1998 Elsevier Science S.A. All rights reserved.

1998 - Properties of glasses belonging to the Li2O-ZrO2-SiO2 system [Articolo su rivista]
APN de, Oliveira; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; G., Ramis; M., Trombetta; G., Busca
abstract

The behaviour and some physical, chemical and thermal properties of Li2O-SiO2 glasses with ZrO2 additions (in the form of ZrSiO4) of up to 13.00 mol% in the as-quenched state were investigated with the aid of x-ray diffraction (XRD), FT-IR spectroscopy, thermal expansion, microhardness and density measurements as well as chemical durability measurements. Transparent glasses prepared by the addition of ZrO2 up to about 11.00 mol% were obtained. For successive addition of ZrO2 and decreasing Li2O/SiO2 ratio, the expansion coefficients revealed decreasing values from 12.60x10(-6) to 8.69x10(-6)degrees C-1. The glass transition and softening point temperatures of the glasses showed a reverse behaviour. By increasing the ZrO2 content in the base glasses the hardness and density values increased. However, while hardness increases even with the decrease of the Li2O/SiO2 ratio the density showed a contrary behaviour, i.e. it increased with the ZrO2 content but decreased when the Li2O/SiO2 ratio decreased, with the highest values of 6.73 GPa and 2.71 g/cm(3), respectively. On the other hand, the chemical durability, in the case of 30Li(2)O.70SiO(2) base glass, decreased with time in water solution and increased with ZrO2 content tending to be almost constant for ZrO2 contents higher than 4.76 mol% at 60 min and 6.98 mol% in the time range from 5 to 30 min, respectively.

1998 - Sintering and crystallization of a glass powder in the Li 2O-ZrO2-SiO2 system [Articolo su rivista]
A. P., Novaes De Oliveira; Manfredini, Tiziano; Barbieri, Luisa; Leonelli, Cristina; Pellacani, Gian Carlo
abstract

Sintering and crystallization of a 23.12 mol% Li2O, 11.10 mol% ZrO2, 65.78 mol% SiO2 glass powder was investigated. By means of thermal shrinkage measurements, sintering was found to start at about 650°C and completed in a very short temperature interval (ΔT ≈ 100°C) in less than 30 min. Crystallization took place just after completion of sintering and was almost complete at about 900°C in 20 min. Secondary porosity prevailed over the primary porosity during the crystallization stage. The glass powder compacts first crystallized into lithium metasilicate (Li2SiO3), which transformed into lithium disilicate (Li2Si2O5), zircon (ZrSiO4), and tridymite (SiO2) after the crystallization process was essentially complete. The microstructure was characterized by fine crystals uniformly distributed and arbitrarily oriented throughout the residual glass phase.

1997 - Effect of TiO2 addition on the properties of complex aluminosilicate glasses and glass-ceramics [Articolo su rivista]
Barbieri, Luisa; Corradi, Anna; Leonelli, Cristina; Siligardi, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo
abstract

The nucleating effect of titania during glass crystallization has been studied in a complex glassy system where some particular oxides, such as ZnO and MgO, which present chemical and thermodynamic affinity for titanium have been added. Such additions tend to produce phase separation in the glass and leads to titanate phases formation in the glass-ceramic. Moreover, the presence of lithia has a promoting effect on both mechanisms because the lowered viscosity increases cation diffusion. Various thermal, microscopic, and diffractometric techniques have been used to investigate the amorphous and the crystalline phase.

1997 - Zeolititi nazionali nella depurazione di acque reflue e loro successivo utilizzo in impasti ceramici [Articolo su rivista]
Andreola, Nora Maria; Manfredini, Tiziano; Passaglia, Elio; Pellacani, Gian Carlo
abstract

Vengono riportati i risultati di uno studio eseguito con lo scopo di valutare la capacità di una zeolite italiana nella depurazione di una soluzione contenente Pb, Ba e Zn ed il suo successivo utilizzo all'interno di imapsti ceramici per la produzione di piastrelle da pavimentazione.

1996 - Alumina-chopped fibres as reinforcements for glass-ceramic materials [Articolo su rivista]
Leonelli, C.; Manfredini, T.; Pellacani, G. C.; Blundo, D. S.
abstract

The paper reports a preliminary study about alumina short fibres (20 mass-%) and particulate reinforced glass-ceramic matrix composites. The fabrication techniques used are: a) preparation of pellet containing randomly distributed fibres and particulate, by wet mixing, cold pressing and sintering of the dried powders; b) tape casting. The nature of the matrix was investigated in order to obtain good interfacial properties; a new calcium and magnesium aluminosilicate (CMAS) glass ceramic formulation is proposed. The sintering behaviour of composites was studied at different temperatures, ranging from 800 to 1000°C, using scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The evaluation of linear shrinkage and density was sufficient to define the best sintering conditions, while SEM and XRD indicated the nature of matrix/fibre interface's.

1996 - Physical properties of quenched glasses in the Li2O-ZrO2-SiO2 system [Articolo su rivista]
AP NOVAES DE, Oliveira; Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo
abstract

The behavior and some physical and thermal properties of a 30Li(2)O-70SiO(2) base glass composition with addition of ZrSiO4 in the as quenched state was investigated with the aid of X-ray diffraction (XRD), differential thermal analysis (DTA), thermal expansion and microhardness measurements, as well as density measurements. Transparent glasses prepared by the addition of ZrSiO4 up to 10.30 mol% were obtained, ZrSiO4 was found to decrease the expansion coefficient of the investigated glasses from 11.0 x 10(-6) to 7.96 x 10(-6)degrees C-1. The glass transition and softening point temperatures of the glasses showed a reverse behavior. On the other hand, both hardness and density increased for successive increases of the ZrSiO4 amounts, with the highest values of 6.3 GPa and 2.65 g/cm(3), respectively.

1995 - Effects of nucleating agents on diopside crystallization in new glass-ceramics for tile-glaze application [Articolo su rivista]
G., Baldi; Pellacani, Gian Carlo; Leonelli, Cristina; Manfredini, Tiziano; E., Generali; Siligardi, Cristina
abstract

The effect of crystallization produced by addition of TiO2, ZrO2 and P2O5 oxides to glass-ceramic of the system CaO-MgO-SiO2 was studied using structural and thermal techniques. The devitrification process was independent of thermal treatment. X-ray diffraction studies performed on the glass-ceramic system indicated that diopside crystalline phase was more thermodynamically favourable than other phases. The effect of the nucleating agent depends on its nature: TiO2 decreased the activation energy while P2O5 and ZrO2 did not. SEM analysis of the doped glass-ceramics showed randomly distributed crystals with significant dimensional variations from those of the undoped system. All these formulations, showing a high crystallization rate, and a fast heating rate, can be used as tile glazes and/or tile-glaze components.

1995 - Glass ceramics belongings to the CaO-SiO2-ZrO2 system as tiles glazes components [Articolo su rivista]
Baldi di, G.; Barbieri, L.; Frassinelli, L.; Generali, E.; Leonelli, C.; Manfredini, T.; Pellacani, G. C.; Siligardi, C.; Svicher, E. C.
abstract

In order to verify the possibility to use new glass ceramic materials as glazes for floor tiles, the devetrification process of a formulation belonging to the wollastonite stability field in the CaO-SiO2-ZrO2 system was investigated by DTA, XRD and SEM techniques. The investigated system shows a high tendency toward crystallisation, that brings to the separation, also at very high heating/cooling speed, of CaO·SiO2 (wollastonite) and 2CaO·ZrO2·4SiO2 (calcium and zirconium silicate) as main crystalline phases. Industrial tests demonstrate how the formulation can be used as prevalent component in the tile glaze preparation.

1995 - MgO-CaO-Al2O3-SiO2 glassy and glass-ceramic systems: the effect of substitution of CoO or NiO in place of MgO or CaO [Articolo su rivista]
Barbieri, Luisa; Ferrari, Anna Maria; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; S., Bruni; F., Cariati
abstract

Nickel and cobalt were separately incorporated in MgO-CaO-Al2O3-SiO2 glasses Their effect on the crystallisation phenomenon of the amorphous materials into a glass ceramic was investigated by means of thermal analysis and x-ray powder diffraction. These two transition cations decrease the crystal growth of anorthite and diopside and nickel produces forsterite formation. The ionic state and the coordination geometry of Ni and Co ions in the vitreous and the devitrified states have been characterised by means of electronic spectroscopy. Divalent ions were observed for nickel and cobalt in both the glasses and the glass ceramics; in the glasses both Ni2+ and Co2+ are in tetrahedral symmetry, while in glass ceramics the symmetry is predominantly octahedral. Colour changes from glass to glass ceramics correlated well with the cations coordination. The atomic distribution of Ni and Co in the glass ceramics obtained by x-ray fluorescence dispersion spectroscopy complement the information about their coordination environment, the first being present in some crystalline areas and the second being mostly segregated in the residual glass at the grain boundary of crystalline zones.

1995 - Microindentation test as parameter for evaluating the sintering and interface properties of SiC-Whiskers reinforced CMAS glass-ceramic composites [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; D., SETTEMBRE BLUNDO; Siligardi, Cristina
abstract

1995 - PORCELAINIZED STONEWARE TILE [Articolo su rivista]
Manfredini, Tiziano; Pellacani, Gian Carlo; Romagnoli, Marcello; Pennisi, L.
abstract

Dense, low-porosity, small-pore-size tile can be manufactured from kaolin clays at maximum firing temperatures. The unglazed porcelainized stoneware tile can be used for exterior applications and as frost-resistant materials.

1995 - Recycling of Ceramic wastes to reduce pollution [Articolo su rivista]
Andreola, Nora Maria; Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; Romagnoli, Marcello
abstract

Exhausted limes and sludges (containing prevalently glass frits and glaze components), are waste substances to be eliminated. Recycling of about 0.10-0.15 wt% of exhausted lime and about 0.50 wt% of glass frits permits their complete elimination without affecting the industrial process. Release tests demonstrate as the firing process acts in the inertization of soluble heavy-metals ions.

1995 - Study of barium feldspar polymorphism as a function of temperature and calcium content [Articolo su rivista]
Barbieri, Luisa; Corradi, Anna; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo
abstract

A family of new glass-ceramic materials, of the general formula (25-x)CaO.xBaO.yMgO. zAl(2)O(3).5OSiO(2), where x=1, 2, 5, 10, 15, 20, 25, y=20 or 14 and z=5 or 11 (mol%), has been prepared by melting raw materials in two parent glasses and performing heat treatments. The systematic substitution of BaO for CaO in the base glasses allows the effect of feldspars' isomorphism and polymorphism to be studied in a series of glass-ceramics where the structural environment around the bivalent cations, Ca2+ and Ba2+, is systematically altered. Ba2+ has a large effect on the glass transition temperature and dilatometric softening point, causing a decrease with increasing BaO. The crystalline phases have been identified and found to be dependent on the preparation conditions, which are the BaO and Al2O3 contents, the heating rate and the soaking temperature adopted for the crystallization treatments. The infrared spectroscopy technique helped to identify the different polymorphs of barium feldspar, that were not clearly distinguishable by X-ray powder diffractometry due to preferred orientations. The kinetic parameters for the formation of the different crystals have also been determined and correlated with their thermal stability resumed in the well-known time-temperature-transformation curves.

1994 - CONCENTRATED GLAZE SUSPENSIONS [Articolo su rivista]
Andreola, Nora Maria; Corradi, Anna; Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo
abstract

The effect of grinding time, solid slip content, kaolin plasticizer and Ca2+ flocculating agent on the rheological behavior of a typical industrial frit used in glazes for monoporosa wall tile are described.

1994 - Deflocculation of concentrated aqueous clay suspensions with sodium polymethacrylates [Articolo su rivista]
Corradi, Anna; Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo
abstract

The ability of sodium polymethacrylate salts with various molecular weights (1200 to 30000 g.mol(-1)) to deflocculate concentrated aqueous suspensions (58 wt%) of two clays, widely used for stoneware ceramic tile production, was investigated. Rheological measurements were made in distilled water or in water containing calcium ions (O to 6 x 10(-3) mol.dm(-3)) to evaluate the practical applications of these salts as deffocculants in the ceramic tile industry. All slips presented a non-Newtonian behavior. Polymethacrylates with low molecular weights were the most efficient deflocculants for clay suspensions. The salts acted by an essentially electrosteric stabilization mechanism, in combination with a high sequestering ability toward flocculating cations. For their efficient deflocculating capabilities toward concentrated aqueous clay suspensions, sodium(I) polymethacrylates may be considered for practical industrial application, in particular for the preparation of liquid deflocculants.

1994 - Influence of mica coating on interfacial debonding of a SiC fibers reinforced glass-ceramic [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; D., SETTEMBRE BLUNDO; S., Meriani; O., Sbaizero
abstract

1994 - Influenza del rivestimento di mica su fibre SiC sul distacco interfacciale in vetroceramici compositi [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; D., SETTEMBRE BLUNDO; S., Meriani; O., Sbaizero
abstract

1994 - POLYNUCLEAR CHLOROCADMATE(II) COMPOUNDS WITH RIBBON-LIKE STRUCTURES - SYNTHESIS, STRUCTURAL CHARACTERIZATION AND THERMAL-BEHAVIOR [Articolo su rivista]
Corradi, Anna; Cramarossa, Mr; Pellacani, Gian Carlo; Battaglia, Lp; Giusti, J.
abstract

In this paper we report the synthesis and the structural characterization of two polynuclear chlorocadmate(II) systems with ribbon-like structure of formula (H(2)eten)[Cd2Cl6] . H2O (H(2)eten = ethylethylenediamine dication) and (Hetpipd)(2)[Cd5Cl12(H2O)(2)] . H2O (Hetpipd = 1-ethylpiperidine cation), respectively. (H(2)eten)[Cd2Cl6] . H2O crystallizes in space group P2(1)/a. The unit cell dimensions are a = 16.910(2), b = 13.570(2), c = 6.701(3) Angstrom, beta = 94.93(2)degrees, V = 1532(1) Angstrom(3), Z = 4. The final R value is 0.029 (R(w) = 0.028). Its structure consists of organic dications, polymeric ribbons formed by two infinite zig-zag chains running along the z axis linked by a common edge between adjacent octahedra and uncoordinated water molecules. The (Hetpipd)(2)[Cd5Cl12(H2O)(2)] . H2O crystallizes in space group C2/c. The unit cell dimensions are a = 26.811(2), b = 6.643(3), c = 21.724(2) Angstrom, beta = 111.25(3)degrees, V = 3606(2) Angstrom(3), Z = 4. The final R value is 0.039 (R(w) = 0.045). Its structure consists of alternate trinuclear [Cd3Cl6(H2O)(2)] and dinuclear [Cd2Cl6](2-) units, forming polymeric ribbons, organic cations and uncoordinated water molecules. Both packings are strengthened by hydrogen-bond interactions between anions and cations. The thermal properties for both compounds are discussed.

1994 - Preparazione di un pigmento ceramico nero per calcinazione di miscele di ossidi o di polveri ottenute per co-precipitazione [Articolo su rivista]
Ferrari, Anna Maria; Manfredini, Tiziano; Monari, G.; Pellacani, Gian Carlo; Siligardi, Cristina
abstract

Scopo del lavoro è la messa a punto di una metodologia di riferimento per la sintesi di pigmenti ceramici. Sono state valutate le variabili di processonella preparazione di un pigmento ceramico e le tecniche più opportune per la caratterizzazione chimico-fisica. Allo scopo è stato scelto un pigmento nero ferro-cromo di notevole interesse industriale.

1994 - SINTERING BEHAVIOR OF TAPE-CAST CMAS GLASS-CERAMIC REINFORCED WITH ALUMINA CHOPPED FIBERS [Articolo su rivista]
Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; Blundo, Ds
abstract

The sintering behaviour of CMA S glass-ceramic and CMAS glass-ceramic/alumina chopped fibre (20 wt%) composites was studied at different temperatures, ranging. from 800 to 1000-degrees-C, using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and porosimetry investigations. The evaluation of linear shrinkage, density and porosity were sufficient to define the best sintering conditions, while SEM and XRD allowed the nature of the matrix/fibre interface to be studied.

1994 - Solubility, reactivity and nucleation effect of Cr2O3 in the CaO-MgO-Al2O3-SiO2 glassy system [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; Siligardi, Cristina; E., Tondello; R., Bertoncello
abstract

The effect of Cr2O3 on some anorthite-diopside glass-ceramics has been investigated up to amounts of 5 mol%. The solubility in the glassy compositions analysed is total for the oxide, but for amounts higher than 0.5 mol%, an insoluble spinel form, MgCr2O4, precipitates. Ultraviolet-visible spectroscopy has proved to be the most sensitive technique to the presence of Cr(III) in a crystalline spinel site, followed by X-ray diffraction and scanning electron microscopy observations. Electron spin resonance and X-ray photoelectron spectroscopy techniques excluded any oxidation state, other than Cr3+. The influence:of the transition cation on glass nucleation is that of an increasing bulk effect with chromium, and thus chromium-spinel, content. The magnesium content affects spinel formation, while heat treatments up to 1100 degrees C do not. The spinel formation influences the anorthite-diopside ratio in the glass-ceramic, with a large favour towards the pyroxene.

1994 - Utilization of an Italian zeolitite in ceramic bodies [Articolo su rivista]
Andreola, Nora Maria; Manfredini, Tiziano; Passaglia, Elio; Pellacani, Gian Carlo; Pozzi, Paolo; Romagnoli, Marcello
abstract

UTILIZATION OF ITALIAN ZEOLITITE IN CERAMIC BODIESThe papers reports a laboratory and industrial study on the possibility of using an Italian natural zeolitite, both in natural and Pb-; Ba- exchanged form, in a tile ceramic body. Because of their exchangeable cation contents (Na+, K+; Ca+2, Ba+2, Pb+2), natural and exchanged zeolitites can be added (up to 20 and 5wt%, respectively) in a ceramic body, thus favouring its sinterability and unaffecting the crystalline phase formation and the final products characteristics. The addition of higher amounts enhaces the swelling of the tiles during firing and strongly modifies the features of the fired tiles. Release tests in acetic and nitric acid solutions on unfired and fired tiles containing exchanged zeolitites demostrated the inertization of lecheable Pb+2 during firing.

1994 - Vetroceramici appartenenti al sistema CaO-SiO2-ZrO2 come componenti di smalti per piastrelle [Articolo su rivista]
G., Baldi; Barbieri, Luisa; L., Frassinelli; E., Generali; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; Siligardi, Cristina; C., Svicher
abstract

1993 - Addition of exhausted lime in ceramic bodies: possibilities for an environmentally compatible tile production [Articolo su rivista]
Andreola, Nora Maria; L., Bonfatti; Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; Romagnoli, Marcello
abstract

Pollution caused by inorganic wastes in the traditional ceramics industry is minimised by utilising exhausted limes, which are the byproducts in bag filters after the purification of flue gases in wet tile production. This study determined which quantities of exhausted lime added to tile bodies did not significantly affect the physico-chemical properties of the slips (i.e. density /viscosity/deflocculant amount) during wet grinding in ball mills. The results demonstrated that these conditions are obtained when exhausted lime in the bodies does not exceed 0.10 to 0.12 mass%. Furthermore, any increase in fluorine emission in the firing of tiles with exhausted lime can be trapped in the bag filters by increasing the lime content by about 10 mass%. The laboratory and industrial results are also compared.

1993 - Additions and Corrections: Structural and Spectroscopic Correlations in Cadmium(II) Halide Complexes of 2,2-Dimethylpropane-1,3-diamine: (Inorg. Chem. (1992) (31)8, (1401–1406) (10.1021/ic00034a020)) [Articolo su rivista]
Masciocchi, N.; Moret, M.; Sironi, A.; Bruni, S.; Cariati, F.; Pozzi, A.; Manfredini, T.; Menabue, L.; Pellacani, G. C.
abstract

Page 1401. The space group for compound 1, Cd(dmpd)2l2 (dmpd = 2,2-dimethylpropane-1,3-diamine), has been misprinted, both in the Abstract and in Table I, as P21/c (No. 14). The correct space group should read as P21 (No. 4), to which all reported computations and geometrical parameters correctly refer. © 1993, American Chemical Society. All rights reserved.

1993 - Colouring inorganic oxides in MgO-CaO-Al2O3-SiO2 glass-ceramic systems [Articolo su rivista]
Barbieri, Luisa; C. L., Bianchi; S., Bruni; F., Cariati; Leonelli, Cristina; Manfredini, Tiziano; M., Paganelli; Pellacani, Gian Carlo; U., Russo
abstract

Glasses in the system MgO-CaO-Al2O3-SiO2, in which CuO, Fe2O3 and MnO were substituted for CaO, were prepared and crystallized in absence of nucleating agents. Surface nucleation dominated for all compositions, and was followed by growth of only anorthite and diopside. The relative amount of each crystal was influenced by the chemical composition and the nature of the transition metal cation. Cu and Mn segregated at the grain boundary during crystallization and Fe did not. Changes in the coordination symmetry and oxidation states of the transition metal ions in the glassy and glass-ceramic phases are as follows: Cu(II) is sixfold coordinated with regularly octahedral symmetry in glass and distorted in glass-ceramic, while the ratio Cu(II)/Cu(I) is decreased from 5 to 2 during crystallization. Fe(III) is fourfold coordinated with a symmetry C2v and Fe(II) is present, more in the glass-ceramic than in the glass, with an octahedral symmetry. Mn(II) is in cubic site symmetry with a rhombic distortion, more visible in the glass; Mn(III) is sixfold coordinated with octahedral symmetry in a constant ratio (Mn(III): Mn(II) is 2:1) during crystallization.

1993 - Fiber, whisker and particulate reinforced new glass-ceramic matrix for innovative composites [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; Pellacani, Gian Carlo; D., SETTEMBRE BLUNDO
abstract

1993 - Non-isothermal kinetic equations applied to crystallization of glasses [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; Romagnoli, Marcello; Pellacani, Gian Carlo; Siligardi, Cristina
abstract

1993 - Recycling of ceramic wastes in tile bodies to reduce pollution [Articolo su rivista]
Andreola, Nora Maria; Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; Romagnoli, Marcello
abstract

During recent years, special attention has been devoted both to solving pollution problems during the manufacturing of ceramics and to learning how ceramics can themselves be a solution. Waste encapsulation opportunities for structural clay products have been studied. These opportunities affect environmental isolation within the semivitreous matrix of the product and remove and destroy volatile organic components of the waste and recrystallized incinerator slags and encapsulant for such heavy metals as lead. To reduce hazards to workers and community and to realize a safe environment, some manufacturers have planned for a production process that recycles wastes. This plan represents the best option to reduce or minimize pollution by permitting the complete elimination of wastes and thus avoiding their very expensive storage in appropriate dumps. Studies have been performed to evaluate the effects of the presence of exhausted lime and sludges in tile bodies and to obtain information for the rationalization of the recycling process. The focus has been on the evaluation of the effects of the presence of wastes on the rheological and thermal behavior of the tile bodies. In addition, the efficiency of the firing process on the wastes and heavy-metals inertization has been determined by release tests of the fired products in different acidic media.

1992 - A Study of Materials Suitable to Produce Bioceramics with Controlled Porosity for Prosthetic Implants Stabilized by Bone Tissue Ingrowth [Articolo su rivista]
Menabue, Ledi; Forti, Luca; Pellacani, Gian Carlo; M., Fabbri; A., Krajewski; A., Ravaglioli; G., Giunchi
abstract

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

1992 - Kinetic study of surface nucleated MgO-CaO-Al2O3-SiO2 glasses [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; M., Paganelli; Pellacani, Gian Carlo
abstract

The paper investigated, by means of thermal analysis measurements. the validity of three different methods for the evaluation of the activation energy of crystallization for surface nucleated glasses belonging to the MgO-CaO-Al2O3-SiO2 system, separating anorthite and diopside crystals. The values obtained from Kissinger equation of the activation energy for crystallization are comparable with those obtained by other authors for similar glassy systems, 90 to 150 kcal/mol. The results of the kinetic analysis using single-crystallization-peak method should be corrected taking into account the dimensionality of crystal growth.

1992 - Microstructure and thermal properties in the RO-MgO-Al2O3-SiO2 (R=Ca, Sr, Ba, Zn) glass-ceramic systems [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; M., Paganelli; Pellacani, Gian Carlo
abstract

1992 - Reactivity of CaF2 Toward Components of Ceramic Bodies. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Manfredini, Tiziano; Pellacani, Gian Carlo; Romagnoli, Marcello
abstract

The production of ceramic tiles results in the expulsion of many wastes. One of the waste substances which could be eliminated from the tile-making process is the exhausted lime which contains calcium fluoride as the main component. The maximum amount of exhausted lime which can be recycled without modifying the properties of the tiles is determined. The effects of the calcium fluoride on the microstructure of the tiles is investigated. It is discovered that addition of CaF2 greater than 0.5-1.0 wt% results in a strongly modified microstructure. Anorthite is produced at the expense of mullite leading to swelling of the tiles at the industrial firing temperatures.

1992 - STRUCTURAL AND SPECTROSCOPIC CORRELATIONS IN CADMIUM(II) HALIDE-COMPLEXES OF 2,2-DIMETHYLPROPANE-1,3-DIAMINE [Articolo su rivista]
Masciocchi, N; Moret, M; Sironi, A; Bruni, S; Cariati, F; Pozzi, Paolo; Manfredini, Tiziano; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1992 - SYNTHESIS AND CHARACTERIZATION OF LAYERED CHLOROCADMATES(II) WITH PEROVSKITE-LIKE STRUCTURES [Articolo su rivista]
Battaglia, Lp; Corradi, Anna; Pelosi, G; Cramarossa, Mr; Manfredini, Tiziano; Pellacani, Gian Carlo; Motori, A; Saccani, A; Sandrolini, F; Brigatti, Maria Franca
abstract

The synthesis and the structural, thermal, and electrical characterization of tetrachlorocadmate(II) systems, with perovskite-like structures, are described. The countercations are diprotonated amines, such as the ethylenediamine and propane-1,3-diamine dications. The structural model of the compounds consists of layers extending to the ab plane of CdCl6 corner sharing octahedra. The holes between these layers are occupied by alkylammonium ions stabilizing the structure through hydrogen bonding. Thermal analysis shows the presence of a first-order phase transition in the propane-1,3-diammonium compound, related to the disordering of the hydrocarbon chains at high temperatures which causes a decrease in the c parameter and minor differences in the a and b parameters. The electrical conductivity of the investigated compounds is apparenly protonic and seems to increase as the distance between the layers containing the inorganic chains increases.

1991 - CRYSTALLIZATION OF SOME ANORTHITE DIOPSIDE GLASS PRECURSORS [Articolo su rivista]
Leonelli, Cristina; Manfredini, Tiziano; Paganelli, M; Pozzi, Paolo; Pellacani, Gian Carlo
abstract

Anorthite and diopside have been obtained from complete devitrification of glasses belonging to the quaternary system MgO-CaO-Al2O3-SiO2. Microstructure, the natural trend of the nucleation mechanism and kinetic studies on the crystallization phenomenon have been investigated by means of optical and electron microscopies, thermal and thermomechanical techniques and X-ray powder diffractometry. All the glasses investigated show a complete crystallization starting from a simple surface nucleation process. The activation energy for the crystallization process proved to be higher than that for viscous flow, leading to an important aspect modification in the sample during ceramization. Thermal stability and physical properties of both glass and glass-ceramic materials have been tested, suggesting the possible use of these materials in industrial application.

1991 - DISCONTINUOUS WET-GRINDING OF RAW-MATERIALS IN THE PRODUCTION OF TRADITIONAL CERAMIC TILES [Articolo su rivista]
Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; Corradi, Anna
abstract

The paper reports a laboratory and semi-industrial study on the discontinuous wet-grinding raw-material process which is widely used in the ceramic tile industry for body preparations. It focuses on the importance of controlling the rheology and particle size distribution of the aqueous suspensions and the mineralogical characteristics and amounts of the grinding residues of three raw materials-two clays (named Badia and Riola), and one sand-and of their 1/1/1 mix, generally used in factories for the production of porous, single-fired ceramic wall tiles. The apparent viscosities of the electrostatically deflocculated slips strongly depend on the grinding times. The highest solids content of the slips, enabling a good industrial workability, is about 55 to 57 wt% for both the clays, 70 to 72 wt% for the sand, and 60 to 62 wt% and 66 wt% for the mix (body) examined in the laboratory and semi-industrial experiments, respectively In all the samples, the weighted grinding residues on the 45-mu-m sieves, formed of the hard unclayey materials. decrease with increasing grinding times, attaining practically constant values at about 20 and 150 min, respectively, in the laboratory and semi-industrial experiments. The optimum apparent viscosity values, which enable the best grinding action on a ceramic body in a drum ball mill, are greater than those required for moving the final slip to the spray dryer. The results suggest that the grinding action is exerted only on the nonplastic materials. Therefore, the individual grinding of the raw materials forming the ceramic body is strongly indicated for optimization of the wet-grinding process. Other useful hints for the rationalization of the wet-grinding process, which may contribute to increasing production, lowering costs, and improving quality, are suggested.

1991 - LI2O-SIO2-AL2O3-MEIIO GLASS-CERAMIC SYSTEMS FOR TILE GLAZE APPLICATIONS [Articolo su rivista]
Leonelli, Cristina; Manfredini, Tiziano; Paganelli, M.; Pellacani, Gian Carlo; Albaro, J. L. A.; Navarro, J. E. E.; Orts, M. J.; Bruni, S.; Cariati, F.
abstract

In order to verify the possibility of using glass-ceramic materials as tile coatings, the devitrification processes of three industrial formulations belonging to the Li2O-Al2O3-SiO2 glass-ceramic system were investigated by differential thermal analysis, X-ray diffractometry, scanning electron microscopy, and IR spectroscopy. Compositional variations were made by addition of large amounts of MgO or CaO or PbO (ZnO) oxides as well as through smaller additions of other oxides. In these systems the surface crystallization contributes appreciably to the bulk crystallization mechanism. All the systems investigated show a high tendency toward crystallization even at very high heating rates, developing a very close network of interlocked crystals of synthetic beta-spodumene-silica solid solutions (LiAlSi4O10). The results of this research are expected to establish the conditions under which these glass-ceramic systems can be practically used as tile glazes.

1991 - THE RECYCLING OF CERAMIC SLUDGES IN THE PRODUCTION PROCESS - AN OPTION FOR CERAMIC TILE FACTORIES TO REACH ZERO POLLUTION [Articolo su rivista]
Manfredini, Tiziano; Marzola, G; Nunziello, S; Pellacani, Gian Carlo; Pozzi, Paolo; Tubertini, O.
abstract

The paper considers a way of minimizing the pollution due to ceramic sludges, by rationalizing the addition of waste waters and sludges in tile production processes. The analytical and rheological results, obtained on the body slips used for white gres tile production in waste or purified waters, demonstrate that the addition of dried sludges up to 5% wt (in place of the < 2% wt amount till now used) makes the slip completely compatible with industrial requirements. This paper evidences the possibility of direct use of waste waters, containing sludges, in the wet grinding process, making purification treatments of waters unnecessary and greatly reducing the economical engagement.

1990 - CRYSTAL-STRUCTURE, THERMAL-PROPERTIES, AND SPECTROSCOPY OF (N,N'-DIMETHYLPIPERAZINIUM)[CUCL3(H2O)]2 AND (2-AMINOPYRIMIDINIUM)[CUCL3(H2O)] [Articolo su rivista]
Manfredini, Tiziano; Pellacani, Gian Carlo; Corradi, Anna; Battaglia, Lp; Guarini, Ggt; Giusti, Jg; Pon, G; Willett, Rd; West, Dx
abstract

CRYSTAL-STRUCTURE, THERMAL-PROPERTIES, AND SPECTROSCOPY OF (N,N'-DIMETHYLPIPERAZINIUM)[CUCL3(H2O)]2 AND (2-AMINOPYRIMIDINIUM)[CUCL3(H2O)]

1990 - Le bentoniti e la plasticità degli impasti ceramici [Articolo su rivista]
L., Boscardin; Manfredini, Tiziano; G. F., Marzola; C., Pasquali; Pellacani, Gian Carlo; Pozzi, Paolo
abstract

Vengono riportati i risultati relativi ad uno studio sull'effetto dell'aggiunta di bentoniti sulla plasticità degli impasti ceramici

1990 - Monomeric and oligomeric phosphates as deflocculants of concentrated aqueous clay suspensions [Articolo su rivista]
Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, P.; Bonamartini Corradi, A.
abstract

The paper discusses on effects of monomeric and oligomeric phosphates as deflocculants of concentrated aqueous clay suspensions

1990 - Redox equilibria in metalloproteins and characterization of model complexes [Capitolo/Saggio]
Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; Sola, Marco; L. P., Battaglia; Corradi, Anna; J. A., Cowan
abstract

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

1990 - SULFONAMIDE NITROGEN-CONTAINING N-PROTECTED AMINO-ACIDS INTERACTING WITH PALLADIUM(II) - POLAROGRAPHIC AND PH-METRIC INVESTIGATION IN AQUEOUS-SOLUTION [Articolo su rivista]
Gavioli, Giovanna; Borsari, Marco; Menabue, Ledi; Saladini, Monica; Pellacani, Gian Carlo; Sola, Marco
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

1989 - Flexibility in coordinative behavior of propane-1,3-diamine toward Zn(II) and Cd(II) halides:[M(1,3pn)2X2 (M=Zn, Cd; X=Cl, Br,I)]. [Articolo su rivista]
G., Ciani; M., Moret; A., Sironi; S., Bruni; F., Cariati; A., Pozzi; Manfredini, Tiziano; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1989 - Polymeric 1-D linear-chain piperidinium and morpholinium trichlorocadmates (II): Synthesis and structural, thermal and electrical properties [Articolo su rivista]
Manfredini, T.; Pellacani, G. C.; Battaglia, L. P.; Corradi, A. B.; Giusti, J.; Motori, A.; Saccani, A.; Sandrolini, F.
abstract

The crystal structures of two polymeric 1-D linear-chain piperidinium and morpholinium trichlorocadmates(II) have been determined. The CdCl3(pdH) (pdH = piperidinium cation) salt is orthorhombic with the following space group and lattice constants: Ama2, a = 6.770(1) A ̊, b = 18.421(6) A ̊, c = 7.642(1) A ̊, Z = 4. Its structure consists of piperidinium cations and polymeric 1-D endless chains of triangular-face sharing distorted octahedral (CdCl6)4- ions, joined via three bridging chlorine atoms. The CdCl3(mfH) (mfH = morpholinium cation) salt is orthorhombic with the following space group and lattice constants: P212121, a = 17.524(4) A ̊, b = 14.368(3) A ̊, c = 7.000(1) A ̊, Z = 4. Its structure consists of zwitterionic 1-D linear Cd2Cl6(mfH)2 chains in which two unequivalent cadmium atoms, Cd(1) surrounded by six chlorine atoms and Cd(2) by four chlorine atoms and two oxygen coordinated morpholinium cations, are present. Alternate CdCl4(cis-Cl2) and CdCl4(cis-O2) distorted octahedra share edges by two chlorine atoms, forming chains of Cd2Cl6(mfH)2 units, running along the z axis. The compounds are also investigated by means of thermal, optical microscopy, X-Ray powder spectra and d.c. and a.c. electrical measurements. In particular for the CdCl3(mfH) salt the two phase transitions appearing at 201 and 211°C are tentatively explained on the basis of the above cited measurements. Correlations among the different parameters and the known structures of these materials are also drawn. © 1989.

1989 - Some general consideration on the rheological behaviour of aqueous clay suspensions: dependence on the physico-chemical properties of inorganic salts, calcium(II)ion presence and grinding times [Articolo su rivista]
Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; A., Blasco Fuentes; F., Negre Medall
abstract

The paper reports some general consideration on the rheological behaviour of aqueous clay suspensions: dependence on the physico-chemical properties of inorganic salts, calcium(II)ion presence and grinding times

1988 - 13C NMR studies of carboxylate inhibitor binding to cobalt(II) carboxypeptidase A [Articolo su rivista]
I., Bertini; R., Monnanni; Pellacani, Gian Carlo; Sola, Marco; B. L., Vallee; D. S., Auld
abstract

Both 13C NMR and electronic absorption spectral studies on cobalt(II) carboxypeptidase A in the presence of acetate and phenylacetate provide evidence for two binding sites for each of these agents. The transverse relaxation rate T2−1 for the 13C-enriched carboxyl groups of the inhibitors is significantly increased when bound to the paramagnetic cobalt carboxypeptidase as compared to the diamagnetic zinc enzyme. The acetate concentration dependence of T2p−1 shows two inflections indicative of sequential binding of two inhibitor molecules. The cobalt-13 C distances, calculated by means of the Solomon equation, indicate that the second acetate molecule binds directly to the metal ion while the first acetate molecule binds to a protein group at a distance 0.5–0.8 nm for the metal ion, consistent with it binding to one or more of the arginyl residues (Arg-145, Arg-127, or Arg-71). In the case of phenylacetate, perturbation of the cobalt electronic absorption spectrum shows that binding occurs stepwise. 13C NMR distance measurements indicate that one of the two phenylacetates is bound to the metal in the EI2 complex. These binding sites may correspond to those identified previously by kinetic means (one of which is competitive, the other noncompetitive) with peptide binding. The studies further indicate that it should be possible to map the protein interactions of the carbonyl groups of both substrate and noncompetitive inhibitors during catalysis by means of 13C NMR studies with suitably labeled substrates and inhibitors.

1988 - Alcune considerazioni generali sul comportamento reologico di sospensioni acquose di argille in funzione delle proprietà chimico-fisiche di deflocculanti inorganici, della presenza di Ioni calcio(II) e dei tempi di macinazione [Articolo su rivista]
Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; A. Blasco Fuentes e. F., Negre Medall
abstract

L'articolo riporta alcune considerazioni generali sul comportamento reologico di sospensioni acquose di argille in funzione delle proprietà chimico-fisiche di deflocculanti inorganici, della presenza di Ioni calcio(II) e dei tempi di macinazione

1988 - Coordinative abilities of ligands which favour S,S chelation: copper(I) halide complexes of N,N'-diphenyldithiomalonamide. The crystal and molecular structure of bis(N,N'-diphenyldithiomalonamide)copper(I) iodide-methanol (2/1). [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; A., Marzotto; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1988 - Effectiveness of the cadmium(II) ion in promoting nitrogen deprotonation. 113 Cd NMR, polarographic, and pH-metric investigations on the Cadmium(II)-N-tosyl-glycinate and Cadmium(II)-N-dansylglycinate systems in aqueous and methanolic systems [Articolo su rivista]
Gavioli, Giovanna; Borsari, Marco; Pellacani, Gian Carlo; Menabue, Ledi; Sola, Marco
abstract

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

1988 - Evidence of a metal-synergistic anion bond in Thallium(III) transferrin [Articolo su rivista]
I., Bertini; L., Messori; Pellacani, Gian Carlo; Sola, Marco
abstract

The 205Tl and 13C NMR spectra of Tl(III)-substituted transferrin have been recorded. Insight has been gained into the metal binding mode of the synerbistic anion carbonate.

1988 - Nickel(II) and Palladium(II) complexes of dithiomalonamides: ligand which favor the formation of pi-conjugation systems in the coordination. [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; A., Marzotto; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1988 - Structural and Magnetic Properties of Dimorpholinium Hexahalodicuprate(II) Salts: Study of two Planar Cu2X62- Dimers [Articolo su rivista]
Scott, B.; Geiser, U.; Willett, R. D.; Patyal, B.; Landee, C. P.; Greeney, R. E.; Manfredini, T.; Pellacani, G. C.; Corradi, A. B.; Battaglia, L. P.
abstract

The chloride and bromide analogues of the title compound were synthesized, and the X-ray crystal structure of the former compound was determined. Magnetic susceptibility and EPR studies were carried out on both compounds. The crystal structure of the chloride salt yielded a triclinic structure, space group P̅1, with a = 7.414 (2) Å,b = 8.686 (2) Å, c = 14.766 (4) Å, α = 79.16 (2)°, β = 82.20 (2)°, γ = 74.19 (2)°, Z = 2, dcalcd = 1.94 g/cm3, and R = 0.0527. The structure consists of isolated planar dimers with each copper atom semicoordinated to two oxygen atoms in what may be described, on the average, as a 4+2 elongated octahedral geometry. The magnetic exchange interaction in the two compounds is predominantly antiferromagnetic with a singlet-triplet splitting energy of J/k = -43.5 (1) K for the chloride and J/k = -131 (2) K for the bromide. EPR and magnetic studies on both compounds indicate that magnetically these compounds are not isolated dimers. EPR studies supplement both the structural and magnetic studies. © 1988, American Chemical Society. All rights reserved.

1988 - The crystal structure, magnetic and electrical properties of two polymeric chlorocuprate(II) compounds. [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; U., Geiser; R. D., Willett; A., Motori; F., Sandrolini; Antolini, Luciano; Manfredini, Tiziano; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1988 - The crystal structures and spectroscopic, thermal and electrical properties of linear and perovskite-type polymeric chlorocadmates (II) [Articolo su rivista]
Manfredini, T.; Pellacani, G. C.; Battaglia, L. P.; Corradi, A. B.; Motori, A.; Sandrolini, F.
abstract

The crystal structures of two polymeric chlorocadmates(II), having triprotonated amines as counterions, have been determined. The CdCl5 (denH3) salt is orthorhombic with the following space group and lattice constants: Pnma, a = 7.208(1) A ̊, b = 24.663(6) A ̊, c = 7.225(1) A ̊, α= β = γ = 90.0°, Z = 4. Its structure consists of sequences of alternating layers of corner-sharing (CdCl6) octahedra (perovskite-type structure) anchored by interposed sheets of aligned diethylenetriammonium cations and of uncoordinated chlorine ions. The Cd2 Cl7 (NametpzH3) · 3H2O salt is triclinic with the following space group and lattice constants: P1̄, a = 9.711(3) A ̊, b = 12.984(3) A ̊, c = 9.201(3) A ̊, α= 107.91(5)°, β = 113.99(5)°, γ = 83.29(3)°, Z = 2. Its structure consists of linear chains of (Cd2 Cl7 (OH2))n3- anions, NametpzH33+ cations and two uncoordinated water molecules. Thermal, far-infrared spectra and d.c. and a.c. electrical measurements are also performed on both the above cited compounds and the anhydrous Cd2 Cl7 (NametpzH3) salt. Correlations among the different electrical parameters (electrical conductivity, dielectric constant and loss factor) and the known structures of these materials are also drawn. © 1988.

1987 - Dithiooxamides as ligands: crystal structures and vibrational analyses of bis(N,N'-dicyclohexyldithiooxamidato)palladium(II) bis(N,N'-dibenzyldithiooxamide)copper(II) diperchlorate, and dichloro(N,N'-dimethyldithiooxamide)zinc(II) and the carbon-13 nuclear magnetic resonance spectra of related compounds. [Articolo su rivista]
Antolini, Luciano; FABRETTI COSTANTINO, Antonio; Franchini, Giancarlo; Menabue, Ledi; Pellacani, Gian Carlo; H. O., Desseyn; R., Dommisse; H. C., Hofmans
abstract

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

1987 - Na-Silicates as Deflocculating Agents for Clays [Articolo su rivista]
Manfredini, T.; Pellacani, G. C.; Pozzi, P.
abstract

In this paper the rheological behavior of clay aqueous suspensions added with various commercial sodium silicates is investigated, in order to evaluate their utilization as deflocculating agents in practical industrial applications. In the sample preparations the industrial experimental conditions have been reproduced as nearly as possible. The best deflocculating conditions of the studied clays were obtained by using a sodium silicate compound having a SiO//2/Na//2O molar ratio of 2/1. This may be explained, since this silicate is the most effective as pH corrector, as deflocculant cation sequestering agent and as colloidal protector.

1987 - Structures and magnetic properties of trinuclear copper(II) halide salts [Articolo su rivista]
T. E., Grigereit; B. L., Ramakrishna; H. L., Place; R. D., Willett; Pellacani, Gian Carlo; Manfredini, Tiziano; Menabue, Ledi; Corradi, Anna; L. P., Battaglia
abstract

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

1986 - C-13 NMR Study of The Synergistic Anion In Transferrins [Articolo su rivista]
I., Bertini; C., Luchinat; L., Messori; A., Scozzafava; Pellacani, Gian Carlo; Sola, Marco
abstract

13C NMR spectra of AI(III), Ga(III), and Zn(I1) derivatives of both human serum transferrin and ovotransferrin with I3C-enriched bicarbonate or oxalate as synergistic anions have been measured at 75.4 MHz. The good quality of the spectra allows us to get detailed information on the state of the synergistic anion. The chemical shift values of the bound anion are interpreted on the basis of the effects arising from the interaction with the protein and the metal and through comparison with simple inorganic complexes. Our ”C NMR spectral data support the idea that the synergistic anion bridges the metal to some positively charged residue of the protein in agreement with the interlocking-sites model proposed by Bates. In the case of the bicarbonate derivatives, chemical shift values suggest carbonate as the form of the bound anion; the arrangements of the anion in the N-terminal and C-terminal sites appear to be identical within the resolution of the technique. The spectral data of the tripositive metal ion derivatives, with oxalate as synergistic anion, show a strong inequivalence between the two carboxylate carbons and are indicative of oxalate monodentate binding to the metal. Oxalate arrangements in the two sites are very similar but not identical. Differences in 13C NMR spectral data between tripositive and bipositive metal derivatives are also discussed.

1986 - Crystal and molecular structure of [H3N(CH2)2NH2(CH2) 2NH3]2HgCl8: A compound containing a discrete axially-compressed trigonal-bipyramidal pentachloromercurate anion [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Antolini, Luciano; Manfredini, Tiziano; Menabue, Ledi; Pellacani, Gian Carlo; G., Ponticelli
abstract

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

1986 - Rheological Investigations of Clay Suspensions for the Optimization of Deflocculation Process [Articolo su rivista]
Pellacani, G. C.; Manfredini, T.
abstract

The rheological properties of clay aqueous suspensions are investigated in order to optimize the deflocculating dosages. The effects of four deflocculants have been investigated on the slip casting performance. The laboratory study on the deflocculation of casting slips has yielded the parameters from which the most efficient and economically advantageous deflocculant or mixture of deflocculants can be proposed for each ceramic body.

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 [Articolo su rivista]
Antolini, Luciano; L. P., Battaglia; Corradi, Anna; G., Marcotrigiano; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; Sola, Marco
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.

1985 - Coordination behavior of L-glutamic acid: spectroscopic and structural properties of (L-glutamato)(imidazole)copper(II), (L-glutamato)(2,2'-bipyridine)copper(II) and aqua(L-glutamato) (1,10-phenanthroline)copper(II) trihydrate complexes. [Articolo su rivista]
Antolini, Luciano; G., Marcotrigiano; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; Sola, Marco
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.

1985 - Crystal structure and spectroscopic, magnetic, and electrical properties of a copper(II) dimer, melaminium hexachlorodicuprate(II), exhibiting a new stacking interaction [Articolo su rivista]
A., Colombo; Menabue, Ledi; A., Motori; Pellacani, Gian Carlo; W., Porzio; F., Sandrolini; R. D., Willett
abstract

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

1985 - The effect of a dansyl group on the coordinative ability of N-protected amino acids. Part 1. Behaviour of the copper(II) ion-N-dansylglycinate system in aqueous and methanolic solution [Articolo su rivista]
Gavioli, Giovanna; Grandi, Giulia; Menabue, Ledi; Pellacani, Gian Carlo; Sola, Marco
abstract

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

1984 - Magnetic and spectroscopic properties of dimeric copper(II) complexes of N-benzyloxy carbonyl -substituted amino acid anions. [Articolo su rivista]
Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio
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.

1984 - Solid state and ethanolic solution behavior of N-tosylglycinate-copper(II) complexes. Crystal and molecular structure of a strongly coupled polymeric N-tosylglycinato copper(II) complex. [Articolo su rivista]
Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo; Gavioli, Giovanna; Grandi, Giulia; L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio
abstract

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

1984 - Thermal behaviour of [N(2-ammoniumethyl) piperazinium] pentachlorocuprate(II) dihydrate [Articolo su rivista]
J., Giusti; G. G. T., Guarini; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1984 - Thermochromism in copper(II) complexes: Spectroscopic, thermal, and electrical properties and room-temperature crystal structure of bis(2,2-dimethylpropane-1,3-diamine)copper(II) dinitrate [Articolo su rivista]
Menabue, Ledi; Pellacani, Gian Carlo; L. P., Battaglia; Corradi, Anna; F., Sandrolini; A., Motori; R. J., Pylkki; R. D., Willett
abstract

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

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) [Articolo su rivista]
Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; Sola, Marco; L. P., Battaglia; Corradi, Anna
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.

1983 - Coordination behavior of L-aspartic acid: thermal, spectroscopic, magnetic and structural properties of aqua(L-aspartato)(2,2'-bipyridine)copper(II) trihydrate. [Articolo su rivista]
Antolini, Luciano; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1983 - Relation between structures and spectroscopic properties of Group IIB metal [M(chelate)X2] complexes (X = Cl, Br, I). Crystal and molecular structure of [H2NCH2(CH3)2CCH2NH2]MX2 complexes (M = Zn, X = Cl, Br; M = Cd, X = Br) [Articolo su rivista]
F., Cariati; G., Ciani; Menabue, Ledi; Pellacani, Gian Carlo; G., Rassu; A., Sironi
abstract

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

1983 - Role of the tosyl group on the coordination ability of N-protected aminoacids. 3. Ternary complexes of copper(II) with N-tosylglycine and aromatic amines. Crystal and molecular structure of bis(N-tosylglycinato) bis(N-methylimidazole)copper(II). [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1983 - The role of the tosyl group on the coordination ability of N-protected amino acids. 1. Solid-state behaviour of (N-tosylglycinato)copper(II) complexes: crystal and molecular structure of (N-tosylglycinato)triaquacopper(II) and dipotassium Bis(N-tosylglycinato)cuprate(II) complexes [Articolo su rivista]
Antolini, Luciano; Battaglia, L. P.; BATTISTUZZI GAVIOLI, G.; BONAMARTINI CORRADI, A.; Grandi, Giulia; Marcotrigiano, M.; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1983 - The role of the tosyl group on the coordination ability of N-protected amino acids. 2.Behavior of the copper(II) ion-N-tosylglycinate system in aqueous solution. [Articolo su rivista]
Antolini, Luciano; L. P., Battaglia; Gavioli, Giovanna; Corradi, Anna; Grandi, Giulia; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1982 - Coordination behavior of L-aspartic acid: ternary nickel(II) complexes with imidazoles. Crystal and molecular structure of (L-aspartate)tris(imidazole)nickel(II). [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Antolini, Luciano; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1982 - N-(2-Ammonioethyl)morpholinium tetrachlorocuprates(II). The first instance of two forms, one green and one yellow, both stable at room temperature [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1982 - Structural, spectroscopic and magnetic properties of diaqua(L-aspartato)nickel(II) hydrate. [Articolo su rivista]
Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo; Marcotrigiano, Giuseppe Onofrio
abstract

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

1982 - Synthesis and low-frequency vibrational spectra of N-(2-ammoniumethyl)- piperazinium halide-mercurates(II). Crystal structure of N-(ammomoniumethyl)- piperazinium monochloride tetrachloromercurate(II) [Articolo su rivista]
Menabue, Ledi; Pellacani, Gian Carlo; A., Albinati; F., Ganazzoli; F., Cariati; G., Rassu
abstract

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

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) . [Articolo su rivista]
Antolini, Luciano; L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica
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.

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. [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; P., Prampolini
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.

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). [Articolo su rivista]
Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; Marcotrigiano, Giuseppe Onofrio
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.

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 [Articolo su rivista]
Antolini, Luciano; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica
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.

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 [Articolo su rivista]
Battini, Renata; Gavioli, Giovanna; Grandi, Giulia; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; Corradi, Anna
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.

1981 - Copper(II) complexes of N-protected amino acids: synthesis and spectroscopic, magnetic and structural, properties of bis(N-acetyl-beta-alaninato)diaquacopper(II) dihydrate and tetrakis[-(N-acetyl-beta-alaninato] diaquadicopper(II) dihydrate. A case of structural isomerism. [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1981 - Low-frequency vibrational spectra of some 4-benzylpiperidinium and N-benzylpiperazinium pentahalogenoantimonates(III) and pentahalogeno bismuthates(III). Partial crystal structure determination of 4-benzylpiperidinium pentachloroantimonate(III). [Articolo su rivista]
F., Cariati; A., Panzanelli; Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo; Marcotrigiano, Giuseppe Onofrio
abstract

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

1981 - Spectroscopic and structural investigation of two N-benzylpiperazinium tetrachlorocuprates(II), one hemihydrate and one anhydrous: two compounds containing unequally flattened [CuCI4]2-- tetrahedra. [Articolo su rivista]
Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica; Marcotrigiano, Giuseppe Onofrio; W., Porzio
abstract

1981 - Synthesis, spectroscopic and structural properties of 2,2-dimethyl-propane-1,3-diamine copper(II) complexes. Temperature dependent tetragonal distortion in some thermochromic complexes. Crystal and molecular structure of bis(2,2-dimethylpropane-1,3-diamine)-diperchloratecopper(II) [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1980 - (N-acetyl-DL-valinate)copper(II) complexes: effect of amines on the amino acid coordination. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1980 - Complex formation of zinc(II) ion with glycine, N-acetyl- and N-benzoyl-glycine in aqueous and ethanolic solution by polarographic method. [Articolo su rivista]
Andreoli, Roberto; G., Battistuzzi Gavioli; Benedetti, Luca; Grandi, Giulia; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1980 - Preparation, crystal structure and vibrational spectra of N-benzylpiperazinium pentachlorodimercury(II) complexes: (NbzpipzH)Hg X (X=Cl,Br) [Articolo su rivista]
A., Albinati; S. V., Meille; F., Cariati; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1980 - Spectroscopic and structural investigation on the pentachloro- and (mixedpentahalo) cuprates(II) of the N-(2-ammoniumethyl)piperazinium cation. The first case of monomeric entahalocuprate(II) having square-pyramidal structure. Crystal and molecular structure of the (N-(2-ammoniumethyl)piperazinium) pentachlorocuprate(II) dihydrate. [Articolo su rivista]
Antolini, Luciano; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1980 - Spectroscopic and structural investigation on the trihalocuprates(II) of the 4-benzylpiperidinium cation. Crystal and molecular structure of the bis(4-benzylpiperidinium)hexachlorodicuprate(II). [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1980 - Synthesis and spectroscopic and structural investigation on tetrakis(N-(2-ammonioethyl)- piperazinium)di-mu-chloro-dodecachlorocuprate(II) bis(tetrachlorocuprate(II)), (C6H18 N3) Cu5Cl22 [Articolo su rivista]
Antolini, Luciano; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1980 - Synthesis, spectroscopic and structural properties of bis (N-acetyl-DL-tryptophanato)copper(II) complex and its amine adducts: effect of amines on the amino acid coordination. Crystal and molecular structure of diaqua bis(N-acetyl-DL-tryptophanato)bis(pyridine)copper(II). [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1979 - Bis(N-acetyl-DL-leucinate)copper(II) complexes and their amine adducts. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; P., Morini; Pellacani, Gian Carlo
abstract

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

1979 - Cobalt(II), nickel(II) and zinc(II) complexes of peptide group containing amino acids Bis(acetyl-DL-valinate)metal(II) complexes [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo; Saladini, Monica
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.

1979 - Halocuprates(II) of the N-phenylpiperazinium mono- and dications: crystal and molecular structure of N-phenylpiperazinum tetrachlorocuprate(II). Correlation of the electronic spectrum vs. distortion of the CuCl42- anions from tetrahedral symmetry. [Articolo su rivista]
L. P., Battaglia; Corradi, Anna; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1979 - Hydrogen bonding and size effects of the cations on the coordination geometry of the metal ions. Tetrahalocobaltates(II) of the N-ethyl-, 2-ethyl- and 4-benzyl-piperidine cations. Crystal and molecular structure of the bis(4-benzylpiperidinium) tetrachlorocobaltate(II). [Articolo su rivista]
Antolini, Luciano; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1979 - N-acetyl-DL-leucinate cobalt(II), nickel(II) and zinc(II) complexes. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; P., Morini; Pellacani, Gian Carlo
abstract

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

1979 - N-acetyl-DL-tryptophanatometal(II) (Co(II), Ni(II) and Zn(II)) complexes and their amine adducts. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1979 - Solid state vibrational spectroscopy of tin(IV), antimony(III) and bismuth(III) halides of N-ethylmorpholinium cation. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo; M., Tonelli
abstract

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

1979 - Spectroscopic investigation on the tetrahalo- and mixed-tetrahalocuprates of the N-methyl-piperidinium and N,N'-dimethylpiperazinium cations [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Saladini, Monica; Pellacani, Gian Carlo
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.

1979 - Tetrahalo and (mixed-tetrahalo)cuprates of the 1-methyl- and 2-methyl.pyperazinium dications. Hydrogen bonding effects on the coordination geometry of the CuX4 2- anions. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1978 - An IR study (4000-250 cm-1) on the complexes of the group IIB metals with N-acetyl-L-, alfa-N-benzoyl-DL- and benzoyl-beta-alanine. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1978 - Electronic, infrared and far-infrared study on the pseudotetrahedral cobalt(II) zwitterion complexes [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1978 - Solid state vibrational spectroscopy of some piperidinium and morpholinium salts of tin(IV), antimony(III) and bismuth(III) halide complexes. [Articolo su rivista]
F., Cariati; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; F., Morazzoni; Pellacani, Gian Carlo; G. M., Zanderighi
abstract

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

1978 - Spectroscopic investigation of the cobalt(II), nickel(II), copper(II) and zinc(II) tetrahalometallates of the N-ethyl-morpholinium cation. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1977 - Antimony and bismuth trihalide complexes of dithiomalonamide, N,N'-dimethyl- and N,N'-diphenyl-dithiomalonamide. [Articolo su rivista]
Pellacani, Gian Carlo; Peyronel, Giorgio; Malavasi, Wanda; Menabue, Ledi
abstract

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

1977 - Benzoyl-beta-alaninato nickel(II) complexes. The amino effect on the amino acid coordination around the nickel ion. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1977 - Copper(II) complexes of peptide group containing amino acids. Bis(N-acetyl-L-alaninate)copper(II) complexes and their amine adducts. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1977 - Far-IR spectra of the tetrahalocobaltate complexes of the morpholinium,piperidinium, 1-methyl- and 2-methyl-piperazinium cations. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1977 - Study on the pseudotetrahedral and tetrahedral cobalt(II) complexes. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1977 - alfa-N-benzoyl-DL-alaninate nickel(II) complexes. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; P., Morini; Pellacani, Gian Carlo
abstract

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

1976 - (N-benzoyl-DL-alaninate)copper(II) complexes: effects of amines on the amino acid coordination. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1976 - Apparent formation constants of dithiooxamide and substituted dithiooxamide complexes of cobalt(II,III), nickel(II) and copper(II) in strongly acidic media. [Articolo su rivista]
Antolini, Luciano; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1976 - Complexes of peptide-group containing amino acids N-acetyl-L-, alfa-N-benzoyl-DL- and N-benzoyl- beta-alaninate cobalt(II) complexes and their amine adducts. Trans.Met.Chem., 1, 229-233 (1976). [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1976 - Coordination properties of beta-alanine: new complexes with some transition metals: cobalt(II), nickel(II) and copper(II). [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1976 - Copper(I) and silver(I) complexes of dithiomalonamide, N,N'-dimethyl- and N,N'-diphenyldithiomalonamide. [Articolo su rivista]
Pellacani, Gian Carlo; Peyronel, Giorgio; T., Feltri; Menabue, Ledi
abstract

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

1976 - Infrared spectra (4000-60 cm-1) of the antimony(III) and bismuth(III) trihalide complexes with piperidine and piperazine. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1976 - Preparation and study of some dithiolylium salts [Articolo su rivista]
Pellacani, Gian Carlo; Menabue, Ledi
abstract

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

1976 - Spectroscopic investigation of some halide and mixed-halide complexes of zinc(II), cadmium(II) and mercury(II) with piperidinium and morpholinium cations. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1976 - Spectroscopic investigation on the trichloro-, tetrahalo- and mixed-tetrahalocuprates of the piperidinium and morpholinium cations. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1976 - Tetrahalo- and (mixed-tetrahalo)cuprates of the piperazinium dication.Coordination geometry changes in some CuX42- anions. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1976 - Tetrahalocobaltate complexes of morpholinium, piperidinium, 1-methyl- and 2-methyl-piperazinium cations. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1975 - Bis(benzoyl-beta-alaninate)copper(II) complexes and their amine adducts. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1975 - Zinc(II), cadmium(II) and mercury(II) complexes with N-acetyl-glycine (aceturic acid) and their amine adducts. [Articolo su rivista]
Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi; Pellacani, Gian Carlo
abstract

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

1974 - ELECTRONIC AND FAR IR-SPECTRA OF SOME POLYMERIC COMPLEXES OF DITHIOOXAMIDE AND ITS N,N'-DISUBSTITUTED DERIVATIVES [Articolo su rivista]
Menabue, Ledi; Pellacani, Gian Carlo; Peyronel, Giorgio
abstract

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

1974 - Methylcellosolve (2-methoxy-ethanol) as solvent for conductivity measurements on coordination compounds. [Articolo su rivista]
Pellacani, Gian Carlo; Peyronel, Giorgio; Marcotrigiano, Giuseppe Onofrio; Menabue, Ledi
abstract

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

1974 - Nickel(II) and copper(II) complexes with N,N'-diethyldithiooxamide: NiL X (X=Cl,Br,I,ClO4 ) ,CuLX (X=Cl,Br) and CuL (ClO4 ) . [Articolo su rivista]
G., Claser; Pellacani, Gian Carlo; Menabue, Ledi; Peyronel, Giorgio
abstract

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

Università degli studi di Modena e Reggio Emilia

Pubblicazioni