INTERACTION OF MONOSACCHARIDES AND RELATED COMPOUNDS WIT OXOCATIONS OF MO(VI), W(VI) AND U(VI)STUDIED BY NMR SPECTROSCOPY

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Abstract
Proton, 13C and 31P nuclear magnetic resonance spectroscopy has been used to study the complexation of M(VI), W(VI) and U(VI) oxocations with various aldoses, cyclic polyols and ribose-5-phosphate in aqueous solution. The aldoses D-mannose, D-lyxose and D-ribose from tridentate complexes with Mo(VI) and W(VI) at pH ≃ 5, via the 1,2,3-hydroxyl groups, which are cis to each other in these sugars. Other aldoe, like D-arabinose, D-glucos, D-xylose and D-galactose from weaker bidentate complexs with those ions because they can onl use the 1 and 3-cis hydroxyl groups in metal binding. These bidentate interactions also take place in the binding of U(VI) to D-ribose, at pH ≃ 110. However, sugars having 1,3,5-hydroxyl groups in the cis position do not from stable chelates with these oxocations, possibly due to steric crowding. In the case of ribose-5-phosphate, the phosphate group is the exclusive binding site for the three oxocations. except for U(VI) at ver basic pH(pH > 10), where the hdroxyl groups also interact with UO2+ 2.