Ultraviolet-circular dichroism spectra for structural analysis of copper(ii) complexes with aliphatic and aromatic ligands in aqueous solution

TLDR: In this paper, an attempt has been made to identify the characteristic positions, and their eventual displacements with changing co-ordination, of the charge-transfer bands involving donor groups located on molecules of biological interest.

Abstract: An attempt has been made to identify the characteristic positions, and their eventual displacements with changing co-ordination, of the charge-transfer bands involving donor groups located on molecules of biological interest [L-malic acid, N-acetyl-L-aspartic acid, (1R,2R)-cyclohexane-1,2-diamine, L-alanyl-L-alanine, L-γ-glutamyl-L-Iµ-lysine, N-acetyl-L-histidine, β-alanyl-L-histidine and N-benzoylglycyl-L-histidyl-L-leucine] such as carboxylate, alcoholate, amine, deprotonated peptide and imidazole. Information about the species formed in solution was obtained by means of pH-metric readings while ultraviolet–circular 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)–ligand 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.