CHROMATE REDUCTION - REDUCTION OF POTASSIUM CHROMATE BY D-GLUCOSE AND D-FRUCTOSE TO FORM CR(III)-SACCHARIDE COMPLEXES

The reduction of chromate by saccharides is of paramount importance in the context of chromium transport in biological and ecological systems. Potassium chromate has been shown to be reduced by D-glucose and D-fructose to form Cr(III)-saccharide complexes via an intermediate Cr(V) species. These saccharide complexes have been isolated in the solid state for the first time and characterized by analytical, spectroscopic, magnetic and electrochemical methods. Bridged dinuclear saccharide complexes of Cr(III) have been proposed

SOLUBLE COMPLEXES OF EARLY 1ST-ROW TRANSITION-METAL IONS WITH D-GLUCOSE

Glucose complexes of Ti4+, V4+, Cr3+, and Mn2+ ions were synthesized by simple, reproducible procedures in nonaqueous media, isolated in the solid state, and characterized using several analytical and spectroscopic techniques. These are soluble both in water and in several polar organic solvents

REDUCTION OF POTASSIUM CHROMATE BY D-FRUCTOSE, D-GALACTOSE, D-MANNOSE, D-GLUCOSE, AND L-SORBOSE

Chromate is readily reduced by various saccharides under different experimental conditions, and its reduction has been followed using absorption and EPR spectroscopies and electrochemistry. The reduction of Cr(VI) was found to be characteristic of the saccharide used and the reductive capabilities follow a trend, D-fructose > L-sorbose > D-galactose > D-mannose > D-glucose at pH 1.65 and D-fructose > D-galactose > D-mannose > L-sorbose > D-glucose at pH 0.35. Similar trends were noticed from EPR and electrochemistry studies. As the reduction of chromate was found to go via soluble, reactive, and relatively long-lived Cr(V) intermediates having different life times, the biological toxicity and ecological hazard created in the presence of Cr(VI) salts by various molecules containing such saccharide moieties is expected to follow a reverse trend

IN-VITRO REDUCTION OF CR(VI) BY LOW-MOLECULAR-WEIGHT BIOMIMETIC COMPONENTS - A COMPARATIVE-STUDY USING UV-VIS SPECTROSCOPY

Chromium(VI) reduction has been carried out by a variety of molecules of cellular and soil importance, such as thiol containing ones, ascorbic acid, saccharides and their derivatives, and nucleotides and their components using absorption spectroscopy. Based on the absorption data, the reductive abilities of these molecules have been obtained and the trend has been found to be ascorbic acid > thiols >> saccharides > nucleotides

TRANSITION-METAL SACCHARIDE CHEMISTRY AND BIOLOGY - SYNTHESIS, CHARACTERIZATION, REDOX BEHAVIOR, BIOINTERACTION AND DATA CORRELATIONS OF DINUCLEAR CHROMIUM(III) COMPLEXES

A series of dinuclear chromium(III) complexes has been synthesised by reduction of chromate by a variety of saccharides and related compounds. The complexes have been characterised by various analytical (elemental and ICP-AES analysis, TLC, HPLC) and spectroscopic (UV/VIS, FTIR, EPR, H-1 and C-13 NMR) methods. Antiferromagnetic interactions between the two Cr-III centres have been established by magnetic susceptibility measurements and the hydrolytic stability and redox behaviour of the complexes have been established by extensive electrochemical studies which gave several correlations. The interaction of some of the complexes with DNA has been studied by gel electrophoresis

IN-VITRO REDUCING ABILITIES TOWARDS CHROMATE OF VARIOUS HYDROXY-CONTAINING COMPOUNDS, INCLUDING SACCHARIDES AND THEIR DERIVATIVES

The reduction of potassium chromate has been carried out with a variety of OH-containing compounds as reductants, which include pentoses, polyols, glycols, and sugar derivatives. The corresponding reactions were followed using UV-vis and EPR spectroscopies and electrochemistry. The progress of the chromate reduction reactions has been monitored by measuring UV-vis and EPR spectra as a function of time. The observed pseudo first-order reaction rate constants are derived based on the changes in the intensities of the Cr(VI), Cr(V), and Cr(III) signals. Cyclic voltammograms of the simple reductants and their final Cr(III) products formed from the reactions of chromate have also been measured. The reductive abilities of all these reductants have been derived from the spectral data and are discussed on a comparative basis. Based on the results, the aspects that makes a particular reductant more efficient has been addressed. The results obtained from UV-vis, EPR, and cyclic voltammetry are found to be mutually dependent and exhibit among themselves a linear correlation, suggesting that both the reducing and complexing nature of these molecules play important roles in the chromate reduction

TRANSITION-METAL SACCHARIDE CHEMISTRY - SYNTHESIS, SPECTROSCOPY, ELECTROCHEMISTRY AND MAGNETIC STUDIES OF CHROMIUM(III)-HEXOSE COMPLEXES AND THEIR IN-VITRO INTERACTION WITH DNA

Saccharide complexes of Cr(III) were synthesized via chromate reduction. Hexose monosaccharides such as D-glucose, D-fructose, D-galactoSe, D-mannose and L-sorbose and some acid derivatives, such as D-galacturonic acid and D-gluconic acid, were used. The final Cr(III) products were isolated, purified and characterized by various analytical, spectroscopic, magnetic and electrochemical methods. All the products reported here are shown to be dinuclear in nature. The inherent stability and robust nature of these complexes is demonstrated and they are shown to affect the pSV2neo plasmid (DNA) structure in gel electrophoretic experiments