ULTRAVIOLET-CIRCULAR DICHROISM SPECTRA FOR STRUCTURAL-ANALYSIS OF COPPER(II) COMPLEXES WITH ALIPHATIC AND AROMATIC LIGANDS IN AQUEOUS-SOLUTION

An attempt has been made to identify the characteristic positions, and their eventual displacements with changing co-ordination, of the char ge-transfer bands involving donor groups located on;molecules of biolo gical interest [L-malic acid, N-acetyl-L-aspartic acid, (1R,2R)-cycloh exane-1,2-diamine, L-alanyl-L-alanine, L-gamma-glutamyl-L-epsilon lysi ne, N-acetyl-L-histidine, beta-alanyl-L-histidine and N-benzoylglycyl- L-histidyl-L-leucine] such as carboxylate, alcoholate, amine, deproton ated peptide and imidazole. Information about the species formed in so lution was obtained by means of pH-metric readings while ultraviolet-c ircular dichroism spectra were recorded, at fixed pH values, 298 K and I = 0.1 mol dm(-3), for the proton-ligand and proton-copper(II)-ligan d systems, in order to evaluate a spectrum for each complex formed in solution. Intraligand and charge-transfer bands were assigned for each spectrum with the aim of relating spectral features to the structure of the species formed in solution.