Mixed ligand complexes involving ligands of biological importance [Cu(II)-1,10-phenanthroline or 2,2?-bipyridyl-?-amino acids

Abstract

The formation of mixed ligand complexes of Cu(II) with 1,10-phenanthroline or 2,2′-bipyridyl in presence of an α-amino acid (glycine, alanine, phenylalanine or norleucine) have been studied by the pH-metric method. The pH-titrations of the reaction mixtures in equimolar concentrations have shown the simultaneous addition of the ligands resulting 1∶1∶1 ternary complex formation. The equilibrium and formation constants of the resulting ternary complexes have been calculated (30±1 °C; μ=0.1 KNO3). The order of stability in terms of the secondary ligands has been found to be:Phe > Ala > Gly > Norleu.