Enrique J. Baran

Abstract: Metal complexes of the saccharinate anion, obtained by deprotonation of the N–H moiety of saccharin (o-sulfobenzimide) are reviewed A wide variety of metal species based on mononuclear, binuclear, polynuclear complexes and extended coordination polymers are discussed in relation to the coordination modes of the anion, ie, monodentate (through the N-atom or the carbonylic O-atom), bidentate, tridentate or bridge forming The most important physicochemical properties, such as vibrational and electronic spectra, thermal, magnetic and redox properties as well as quantum chemical theoretical studies of these compounds are briefly described With regard to saccharin in food and its health effects, the biological properties of saccharin and its complexes are also summarized Finally, for comparative purposes, a brief overview on the so far characterized metallic complexes of thiosaccharin is given This survey demonstrates that saccharinate is a very versatile and polyfunctional ligand in coordination chemistry

Abstract: Different aspects of the coordination chemistry of oxovanadium(IV) and oxovanadium(V), relevant to the bioinorganic chemistry of vanadium, are presented. Some of the investigated complexes are good models for different aspects of the metabolism and detoxification of vanadium or for a better characterization and understanding of the structural and electronic peculiarities of the coordination spheres of VO2+ and VO2+ in biomolecules. Their structural, spectroscopic and magnetic properties are briefly discussed. The investigated systems include ligands such as reduced and oxidized glutathione, L-ascorbic acid, nucleotides and related systems, carbohydrates, phosphates, carboxylic acids, oxine derivatives and some others.

Abstract: The chemical composition and morphology of solid material isolated from various Cactaceae species have been analyzed. All of the tested specimens deposited high-purity calcium oxalate crystals in their succulent modified stems. These deposits occurred most frequently as round-shaped druses that sometimes coexist with abundant crystal sand in the tissue. The biominerals were identified either as CaC2O4.2H2O (weddellite) or as CaC2O4.H2O (whewellite). Seven different species from the Opuntioideae subfamily showed the presence of whewellite, and an equal number of species from the Cereoideae subfamily showed the deposition of weddellite. The chemical nature of these deposits was assessed by infrared spectroscopy. The crystal morphology of the crystals was visualized by both conventional light and scanning electron microscopy. Weddellite druses were made up of tetragonal crystallites, whereas those from whewellite were most often recognized by their acute points and general star-like shape. These studies clearly demonstrated that members from the main traditional subfamilies of the Cactaceae family could synthesize different chemical forms of calcium oxalate, suggesting a definite but different genetic control. The direct relationship established between a given Cactaceae species and a definite calcium oxalate biomineral seems to be a useful tool for plant identification and chemotaxonomy.

Abstract: The ligand properties of carnosine are analyzed. The stoichiometry, stability constants, and structural and spectroscopic characteristics of its coordination compounds with transition and representative metal cations are discussed. Mixed ligand systems containing carnosine are also presented. The biological activity of some of these metallic complexes is briefly considered.

Abstract: O x o m e t a l l a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 T e t r a o x o m e t a l l a t e s w i t h d%Conf igura t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 T i t a n a t e s , Z i rcona tes a n d H a f n a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 V a n a d a t e s , N ioba tes a n d T a n t a l a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Chromates , Molybda te s a n d T u n g s t a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 P e r m a n g a n a t e s , P e r t e c h n e t a t e s a n d P e r r h e n a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . 89 R u t h e n i u m a n d O s m i u m Te t rox ide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 T e t r a o x o m e t a l l a t e s w i t h dn-Conf igura t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 T e t r a o x o m e t a l l a t e s w i t h d l -Conf igura t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 T e t r a o x o a n i o n s w i t h d2-Conf igura t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 T e t r a o x o a n i o n s w i t h d3-Conf igura t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 T e t r a o x o a n i o n s w i t h d4-Conf igura t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 T e t r a o x o a n i o n s w i t h dS-Configurat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 P e n t a o x o m e t a l l a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 H e x a o x o m e t a l l a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Thioa n d Se lenometa l l a tes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 T e t r a t h i o m o l y b d a t e s a n d t u n g s t a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 O t h e r T e t r a t h i o a n d Te t r a se l enome ta l l a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 T h e Mixed Th iose l enome ta l l a t e s of t h e T y p e A2MS2Se4-x . . . . . . . . . . . . . . . . . . 94 T r i t h i o m o l y b d a t e s a n d t u n g s t a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Othe r Thioa n d S e l e n o O x o c o m p o u n d s w i t h An ions of C3v or C2v S y m m e t r y 94 T h a l l i u m a n d Copper Cha lcogenometa l l a t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

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

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...

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.

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...

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.