Ternary complexes of Cu(II) containing some similar type of amino acids

Abstract

The stability constants of CuAB types of complexes in six ternary, Cu(II)-DL-alanine or β-alanine (A)-DL-2-aminobutyric acid (2-aba), DL-3-aminobutyric acid (3-aba), and 4-aminobutyric acid (4-aba) (B) have been determined pH-metrically at 37°C and I=0.15 (NaClO₄). In aqueous perchlorate medium. The auxilliary data like the acid dissociation constants of these ligands and the stabillity constants of thier binary chelates with Cu(II) have also been obtained under identical conditions. The stability constant data are discussed in terms of statistical effects, steric factors and ring size influence upon chelation. In the ternay systems studied, on marked stabilization is observed compared to the statistical case. The results indicate the preferred formation of Cu(II) ternary chelates containing five and six membered rings rather than those with two rings of same size.