Copper(II) Complexation by D-Glucosamine, Spectroscopic and Potentiometric Studies

The Cu(II) complex formation equilibria of D- glucosamine were studied in aqueous solution by potentiometric and spectroscopic (ESR, CD, absorption spectra) techniques. All data agree that two major species are formed in the pH region 6-9 involving two D-glucosamine ligand molecules bound to the cupric ion via NH2(CuL2) or NH2 and O- (CuH-2L2). In the latter case deprotonated hydroxyls were found to be very effective coordination sites for Cu(II) giving rise to chelate complexes. On the contrary, no complex formation was observed for the Cu(II) N-acetyl-D-glucosamine system.