Oxovanadium(IV) and copper(II) coordination by d-galacturonic and d-glucuronic acids

Potentiometric and spectroscopic studies show that d -galacturonic and d -glucuronic acids are effective ligands for oxovanadium(IV) ions. The carboxylate group initiates the coordination of the metal ion at pH >3 and one or two deprotonated sugar hydroxyl groups are then involved. The position of HO-4 is critical for the resulting equilibria. Cupric ions interact with ligands in a manner similar to that of oxovanadium(IV), although the stabilities of the corresponding complexes are much lower.