Neocuproine copper(ii) complexes with bioactive ligands in aqueous solution

Abstract

A potentiometric titration technique has been used to determine protonation constants of neocuproine {(neo): 2,9-dimethyl-1,10-phenanthroline} and bioactive ligands {(N,O-donor chelator, N,O): glycine (gly), leucine (leu), methionine (met), phenylalanine (phe), tyrosine (tyr), tryptophan (trp), asparagines (asn), glutamine (gln), aspartic acid (asp), glutamic acid (glu)} and their binary and ternary stability constants with copper(II) ion were determined at the constant ionic strength 0.1 M KCl and at 298.15 K. The protonation constants of neo and bioactive ligands and their stability constants of the binary and ternary copper(II) complexes were computed from the potentiometric titration data using BEST program. Furthermore, SPE program was used to determine the distribution of the species formed in solution medium. The stability of the ternary copper(II) complexes are compared with those of the corresponding the stability of the binary copper(II) complexes with regard to Delta logK values.