Enrique J. Baran

Bio: Enrique J. Baran is an academic researcher from National University of La Plata. The author has contributed to research in topics: Infrared spectroscopy & Raman spectroscopy. The author has an hindex of 32, co-authored 589 publications receiving 6392 citations. Previous affiliations of Enrique J. Baran include Technical University of Dortmund & National Scientific and Technical Research Council.

Über Na5[Fe(CN)5SO3]. Eigenschaften und Untersuchung des Zerfalls in wäßriger Lösung

Abstract: Es werden verschiedene Eigenschaften von Na5[Fe(CN)5SO3] beschrieben. Die Untersuchung der Zersetzung in Wasser ergab, das nach einer Protonierung der Sulfitogruppe ein Austausch von SO3H− gegen H2O erfolgt. Die kinetische Messung zeigte, das die Protonierung sehr viel schneller als der Austausch erfolgt und die letztere Reaktion nach einem Gesetz erster Ordnung ablauft. Die Geschwindigkeitskonstante fur den Austausch von SO3H− gegen H2O ergab sich zu 0,0029 ± 0,0002 min−1 fur t = 20°C. Die Elektronenspektren von Na5[Fe(CN)5SO3] sowie weiterer Prussiate wurden gemessen und unter Anwendung der Ligandenfeldtheorie diskutiert. Some properties of Na5[Fe(CN)5SO3] are reported and the decomposition of the compound in water has been studied. The electronic spectra of Na5[Fe(CN)5SO3] and of some other prussiates have been measured and discussed (see Inhaltsubersicht).

A spectrophotometric study of the VO2+-glutathione interactions

Abstract: The interaction of the vanadyl (IV) cation with reduced glutathione (GSH) has been investigated by electronic absorption spectroscopy, at different metal-to-ligand ratios and pH values. The interaction depends strongly on the initial VO2+/GSH ratio. Starting with a tenfold GSH excess, coordination takes place through the two carboxylate groups of the ligand, generating (at pH=7) a blue 1∶2 VO2+/GSH complex; this stoichiometry could be confirmed by photometric titration experiments. Higher GSH concentrations produce a violet complex, which can also be obtained by addition of GSH to the blue species. Some measurements with the three component amino acids of GSH, as well as results obtained from the VO3−/GSH system, allowed a wider insight into the characteristics of this violet complex, in which the cation interacts with S and N atoms of the peptide.

Pd(thiosaccharinato)2·H2O, the first thiosaccharinato complex of a platinum-group metal

Abstract: A Pd(II) complex of the thiosaccharinato (tsac) anion, of stoichiometry Pd(tsac)2·H2O was prepared by interaction of Na2PdCl4 with thiosaccharin in methanol and characterized by infrared and 1H and 13C NMR spectroscopy. These spectral studies confirmed interaction of the metal center with the thiosaccharinate acting as a bidentate ligand through its thiol group and the N-atom. NMR measurements also confirmed that in solution thiosaccharin is mainly present in its thiolate tautomeric form.

The chemistry and biochemistry of vanadium and the biological activities exerted by vanadium compounds.

Abstract: 6.1.2. Aqueous V(III) Chemistry 877 6.1.3. Oxidation State of Vanadium in Tunicates 878 6.1.4. Uptake of Vanadate into Tunicates 879 6.1.5. Vanadium Binding Proteins: Vanabins 879 6.1.6. Model Complexes and Their Chemistry 880 6.1.7. Catechol-Based Model Chemistry 880 6.1.8. Vanadium Sulfate Complexes 881 6.2. Fan Worm Pseudopotamilla occelata 883 7. Vanadium Nitrogenase 883 7.1. Nitrogenases 883 7.2. Biochemistry of Nitrogenase 884 7.3. Clusters in Nitrogenase and Model Systems: Structure and Reactivity 885

The perovskite structure—a review of its role in ceramic science and technology

Abstract: Starting with the history of the fundamental science of the relation of structure to composition delineated completely by Goldschmidt, we use the perovskite structure to illustrate the enormous pow...

CALCIUM OXALATE IN PLANTS: Formation and Function

Abstract: Calcium oxalate (CaOx) crystals are distributed among all taxonomic levels of photosynthetic organisms from small algae to angiosperms and giant gymnosperms. Accumulation of crystals by these organisms can be substantial. Major functions of CaOx crystal formation in plants include high-capacity calcium (Ca) regulation and protection against herbivory. Ultrastructural and developmental analyses have demonstrated that this biomineralization process is not a simple random physical-chemical precipitation of endogenously synthesized oxalic acid and environmentally derived Ca. Instead, crystals are formed in specific shapes and sizes. Genetic regulation of CaOx formation is indicated by constancy of crystal morphology within species, cell specialization, and the remarkable coordination of crystal growth and cell expansion. Using a variety of approaches, researchers have begun to unravel the exquisite control mechanisms exerted by cells specialized for CaOx formation that include the machinery for uptake and accumulation of Ca, oxalic acid biosynthetic pathways, and regulation of crystal growth.

Molecular mechanism mediating proliferation, defferentiation interralationships during progressie development of the osteoblast phenotype

Abstract: I. Introduction A FUNCTIONAL relationship between cell growth and the initiation and progression of events associated with differentiation has been a fundamental question challenging developmental biologists for more than a century. In the case of bone, as observed with other cells and tissue, the relationship of growth and differentiation must be maintained and stringently regulated, both during development and throughout the life of the organism, to support tissue remodeling. For many years, bone was defined anatomically and examined largely in a descriptive manner by ultrastructural analysis and by biochemical and histochemical methods. These studies provided the basis for our understanding of bone tissue organization and orchestration of the progressive recruitment, proliferation, and differentiation of the various cellular components of bone tissue. Now, complemented by an increased knowledge of molecular mechanisms that are associated with and regulate expression of genes encoding phenotypic compone...

Application of Spectroscopic Methods for Structural Analysis of Chitin and Chitosan

Abstract: Chitin, the second most important natural polymer in the world, and its N-deacetylated derivative chitosan, have been identified as versatile biopolymers for a broad range of applications in medicine, agriculture and the food industry. Two of the main reasons for this are firstly the unique chemical, physicochemical and biological properties of chitin and chitosan, and secondly the unlimited supply of raw materials for their production. These polymers exhibit widely differing physicochemical properties depending on the chitin source and the conditions of chitosan production. The presence of reactive functional groups as well as the polysaccharide nature of these biopolymers enables them to undergo diverse chemical modifications. A complete chemical and physicochemical characterization of chitin, chitosan and their derivatives is not possible without using spectroscopic techniques. This review focuses on the application of spectroscopic methods for the structural analysis of these compounds.