Showing papers by "Enrique J. Baran published in 2001"
TL;DR: In this article, a review of the studies of oxovanadium(IV) and oxovadium(V) complexes relevant for the bioinorganic chemistry of vanadium is presented, where the potentialities and possibilities of the spectroscopic methodologies are illustrated and discussed.
Abstract: In this review we present selected examples of our studies of oxovanadium(IV) and oxovanadium(V) complexes relevant for the bioinorganic chemistry of vanadium. Some of the investigated complexes are good models for different steps of vanadium metabolism or for a better understanding of the structural and electronic peculiarities of the coordination spheres of these oxocations in biomolecules. The investigated systems include ligands such as nucleotides, carbohydrates, phosphates, amino acids, oxine derivatives, porphine-like cores and other simple organic and inorganic ligands. All these complexes have been systematically investigated by means of vibrational (infrared and Raman) and electronic spectroscopy and, in some cases, also by thermal and electrochemical behavior. The potentialities and possibilities of the spectroscopic methodologies are illustrated and discussed and some general trends, useful for the structural characterization of these and similar systems, are emphasized.
57 citations
TL;DR: The interaction of sodium metavanadate and VOCl3 with ascorbic acid, one of the possible natural reducing agents of vanadium(V) to oxovanadium(IV), has been investigated and three new VO2+ complexes could be isolated as microcrystalline powders.
Abstract: The interaction of sodium metavanadate and VOCl3 with ascorbic acid, one of the possible natural reducing agents of vanadium(V) to oxovanadium(IV), has been investigated. Three new VO2+ complexes could be isolated as microcrystalline powders. One of them, of composition K1.5Na0.5[VO(HAsc)(OH)3], contains ascorbic acid as a monodentate ligand. In the other two, K[VO(Diketo)(OH)] x H2O and Na3[VO(Diketo)2(OH)], the enolized form of 2,3-diketogulonic acid (one of the oxidation products of ascorbic acid), acts as a bidentate ligand. The complexes were characterized by means of electronic (absorption and reflectance) and infrared spectroscopy and magnetic susceptibility measurements. Their thermal behavior was investigated by thermogravimetric and differential thermal analyses. The interest of the investigated system in relation to vanadium detoxification is also discussed.
22 citations
TL;DR: The crystal structure of the title complex, [Cd(tsac)2(H2O)], has been determined by single crystal X-ray diffraction methods as mentioned in this paper, and the molecular structure was solved from 1705 independent reflections with I > σ(I) and refined to R1 = 0.0489.
Abstract: The crystal structure of the title complex, [Cd(tsac)2(H2O)], has been determined by single crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2/c (a = 12.236(3), b = 8.919(3), c = 16.655(3) A, β = 96.18(2)°, Z = 4). The molecular structure was solved from 1705 independent reflections with I > σ(I) and refined to R1 = 0.0489. Infrared and Raman spectra of the complex were recorded and are briefly discussed. Its thermal behaviour was investigated by thermogravimetry and differential thermal analysis.
19 citations
TL;DR: The infrared and Raman spectra of silver saccharinate Ag(C7H4NO3S) were recorded and discussed in this article on the basis of its structural characteristics.
Abstract: The infrared and Raman spectra of silver saccharinate Ag(C7H4NO3S), were recorded and are briefly discussed on the basis of its structural characteristics and by comparison with the spectra of some related species. Copyright © 2001 John Wiley & Sons, Ltd.
19 citations
TL;DR: The crystal structure of [Tl2(sac)2(H2O)]n (sac''= saccharinate anion) has been solved using single crystal X-ray diffraction as mentioned in this paper.
Abstract: The crystal structure of [Tl2(sac)2(H2O)]n (sac = saccharinate anion) has been solved using single crystal X-ray diffraction. It crystallizes in the triclinic space group P 1 with Z = 2 and presents a polymeric structure formed by two saccharinate anions, one water molecule and two chemically different TlI cations, one 8-coordinate and the other 5-coordinate. Saccharinate shows an unprecedented coordination behavior as it acts as chelating ligand through its N and carbonyl O atoms with the N atom interacting simultaneously with both metal centers, and participation of sulphonyl oxygen atoms in bonding. The most important features of the IR spectrum of the complex are discussed on the basis of the structural peculiarities.
Charakterisierung von Thallium(I) Saccharinat: eine neuartige Bindungsform des Saccharinat Liganden
Die Kristallstruktur von [Tl2(sac)2(H2O)]n (sac = Anion des Saccharins) wurde rontgenographisch an Einkristallen bestimmt. Es kristallisiert in der triklinen Raumgruppe P 1 mit Z = 2 und zeigt eine polymere Struktur, welche aus zwei Saccharinat Anionen, einem Wasser-Molekul und zwei chemisch verschiedenen TlI-Kationen (eines mit der KZ = 8 und das andere mit der KZ = 5) besteht. Das Saccharinat zeigt eine neuartige Bindungsform, da es als Chelatligand uber seine N- und O(carbonyl)-Atome fungiert, wobei das N-Atom gleichzeitig mit beiden Metallzentren in Wechselwirkung tritt, und auch die Sulphonyl-Sauerstoffatome an den Bindungen beteiligt sind. Die wichtigsten Aspekte des IR-Spektrums des Komplexes werden an Hand der Strukturbesonderheiten analysiert und besprochen.
18 citations
TL;DR: The inhibitory effect on alkaline phosphatase activity was tested for this compound as well as for the vanadyl(IV) complexes with maltose, sucrose, glucose, fructose, and galactose, and the monosaccharide/VO complexes appeared as the most potent inhibitory agents.
Abstract: A new vanadyl(IV) complex of the disaccharide lactose was obtained in aqueous solution at pH = 13. The sodium salt of the complex, of composition Na4[VO(lactose)2].3H2O, has been characterized by elemental analysis and by ultraviolet-visible, diffuse reflectance, and infrared spectroscopies. Its magnetic susceptibility and thermal behavior were also investigated. The inhibitory effect on alkaline phosphatase activity was tested for this compound as well as for the vanadyl(IV) complexes with maltose, sucrose, glucose, fructose, and galactose. For comparative purposes, the free ligands and the vanadyl(IV) cation were also studied. The free sugars and the sucrose/VO complex exhibited the lowest inhibitory effect. Lactose-VO, maltose-VO, and the free VO2+ cation showed an intermediate inhibition potential, whereas the monosaccharide/VO complexes appeared as the most potent inhibitory agents.
18 citations
TL;DR: In this article, the least squares computer program letagrop was applied to the experimental emf and UV-Vis data, taking into account hydrolysis of the VO2+ ion.
18 citations
TL;DR: The chemistry of metal-sugar interactions still remains unexplored as discussed by the authors, although the generation of coordination compounds between metallic cations and carbohydrates is a field of increasing interest,1-4.
13 citations
TL;DR: In this article, the Fourier transform infrared and Raman spectra of the low-temperature form of mercury(I) molybdate and the corresponding tungstate were discussed on the basis of their structural characteristics, with the aid of factor group analysis.
Abstract: The Fourier transform infrared and Raman spectra of the low-temperature form of mercury(I) molybdate and the corresponding tungstate were recorded and are discussed on the basis of their structural characteristics, with the aid of factor group analysis. Copyright © 2001 John Wiley & Sons, Ltd.
10 citations
TL;DR: In this article, three mixed oxides of composition Ba 2 LnSnO 5.5, with Ln=Y,Dy,Ho, were prepared by solid state reactions.
10 citations
TL;DR: O complexo de oxovanadio(IV) [VOL2].5H2O (1) and os complexos of oxovanadiio(V) K[VOL2O], [VOL 2OCH3] (4) (L = sal de potassio do acido 7-iodo-8-hidroxiquinolina-5-sulfonico) foram preparados e caracterizados as mentioned in this paper.
Abstract: O complexo de oxovanadio(IV) [VOL2].5H2O (1) e os complexos de oxovanadio(V) K[VOL2O].4H2O) (2), [VOL2OH] (3) e [VOL2OCH3] (4) (L = sal de potassio do acido 7-iodo-8-hidroxiquinolina-5-sulfonico) foram preparados e caracterizados. Os espectros no infravermelho dos solidos foram discutidos e comparados com os de outros compostos semelhantes. Os espectros eletronicos, obtidos em diferentes solventes, tambem foram analisados. Medidas de Raman pre-ressonante dos dois primeiros compostos mencionados acima fortalecem algumas das atribuicoes espectroscopicas.
TL;DR: In this article, the electronic and Raman spectra of Na6[(VO)3(P2O7)3]·7H2O were investigated by means of TG and DTA measurements.
Abstract: The electronic (absorption and reflectance) as well as the infrared and Raman spectra of Na6[(VO)3(P2O7)3]·7H2O were recorded and discussed. Its thermal behavior was investigated by means of TG and DTA measurements. After a two-step dehydration, the compound melts at 464°C and, apparently, depolymerization takes place during this process. The characteristics of the pyrolysis residues, collected at different temperatures, were spectroscopically investigated.
TL;DR: In this paper, the mean amplitudes of vibration of IF3 have been calculated from vibrational spectroscopic data in the temperature range between 0 and 1000 K. Bond properties of the molecule are dis cussed on the basis of these results.
Abstract: Abstract Mean amplitudes of vibration of IF3 have been calculated from vibrational spectroscopic data in the temperature range between 0 and 1000 K. Bond properties of the molecule are dis cussed on the basis of these results. Some comparison with related species are made.
TL;DR: In this paper, the infrared spectra of the mixed oxides Nd 2 BaPdO 5 and Nd2 BaPtO 5, containing Pd(II) and Pt(II), in a square-planar oxygen-coordination, were recorded and approximately assigned on the basis of factor-group arguments.
TL;DR: In this article, the mean amplitudes of vibration of the SOF3− anion were calculated from vibrational spectroscopic data, in the temperature range between 0 and 1000 k. The results are briefly discussed and some comparisons with isoelectronic molecules and ions are made.
TL;DR: In this paper, the mean amplitudes of vibration of the anions BrO2F-2 and IO2F2 were calculated from vibrational spectroscopic data in the temperature range between 0 and 1000 K. Bond proper ties of these species were discussed on the basis of the obtained results and by comparison with known data for related mole cules and ions.
Abstract: Abstract Mean amplitudes of vibration of the anions BrO2F-2 and IO2F-2 have been calculated from vibrational spectroscopic data in the temperature range between 0 and 1000 K. Bond proper ties of these species are discussed on the basis of the obtained results and by comparison with known data for related mole cules and ions.
TL;DR: A number of materials of composition YSr2Cu2.8(XO4)0.2Oy(X = S, P, V) and others in which Y (III) was partially replaced by Sr (II) and/or Ca(II) were prepared by solid state reactions as discussed by the authors.
Abstract: A number of materials of composition YSr2Cu2.8(XO4)0.2Oy(X = S, P, V) and others in which Y (III) was partially replaced by Sr(II) and/or Ca(II) were prepared by solid state reactions. Their unit cell parameters were determined and refined from X-ray powder data. The infrared spectra of the different tetraoxoanions incorporated in these materials were analyzed and discussed in detail. The vibrational modes of the other structural units present in these lattices were also approximately assigned in comparison with known spectral data of related materials.
01 Jan 2001
TL;DR: In this article, hydrogen selenites were obtained and characterized by X-ray powder diffractometry and infrared spectroscopy and their thermal behavior was investigated by means of TG and DTA measuremenis.
Abstract: SUMMARY. The tittle hydrogen selenites were obtained and characterized by X-ray powder diffractometry and infrared spectroscopy. Their thermal behaviour was investigated by means of TG and DTA measuremenis. Several dissolution tests were also performed. The results support the potential usefulness of these salts for selenium supplementation in human and veterinary medicine and to the simultaneous reinforcement of Mg(ii) and CuflI) levels. RESUMEN. '6Mg(Se03R)2.4H20 y CU(S~O~H)~.~H~O: Compuestos Potencialmente Utiles para la Suplementacion de Selenio". Los selenitos acidos del tihilo fueron obtenidos y caracterizados por difractometrfa de rayos X de polvos y espectroscopia de infrarrojo. Su comporiamiento termico fue investigado a traves de medidas TG y ADT. Asimismo, se realizaron diversos ensayos de disolucion. Los resultados apoyan la potencial utilidad de ambas sales para la suplementacion de selenio en medicina humana y veterinaria, asi como para reforzar simultaneamente los niveles de Mg(II) y Cu(ii). INTRODUCIlON Supplementation of essential trace or rnicro