The pH-dependent Variation of the Absorption and Circular Dichroism Spectra in Some Ternary Mixed Complexes of Copper(II) Containing Diethylenetriamine and Optically Active Amino Acids

Abstract

Abstract The absorption and circular dichroism(CD) spectra of some ternary mixed complexes of copper(II) with diethylenetriamine(dien) and various optically active α-amino acids have been measured in an aqueous solution at various pH values. The amino acid may coordinate to one of the planar positions, with its carboxylate or amino group as a unidentate ligand, in a neutral or a very high pH region. On the other hand, from the red shift of the d–d absorption band and the augmentation of the visible CD magnitude, it seems reasonable to expect that a large portion of the amino acid will form a chelate ring with an axial ligation in the pertinent pH region.