pH-metric and electronic spectral measurements on the mixed ligand complexes of copper(II) containing unsubstituted imidazole and some dipeptides

CuAB, CuABH(-l), CuA(2)B or CuA(2)BH(-l) mixed ligand complexes hare been i dentified in the Cu-II-imidazole (A)glycyl-L-phenylalanine, L-phenylalanylg lycine, glycyl-L-tyrosine. L-tyrosylglycine, L-phenylalanyl-L-tyrosine and L-tyrosyl-L-phenylalanine (B) systems. The stability constant values indica te the monodentate binding of imidazole (A) and bidentate binding of the di peptide (B) ligands in the CuAB and CuA(2)B complexes. Both the pH-metric a nd electronic spectral results demonstrate the tridentate mode of binding o f (BH-l) in CuABH(-l). However, in the CuA(2)BH(-l) species tridentate mode of binding of (BH-I) exists only to an appreciable extent.