Oxovanadium(IV) and Copper(II) Coordination by D-Galacturonic and D-Glucuronic Acids

Potentiometric and spectroscopic studies show that D-galacturonic and Dglucuronic 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.