Geometrical, molecular docking and potentiometric studies of sulfoxine and its new azo derivative with their metal complexes

Abstract

A new azo sulfoxine ligand was produced from coupling reaction between 8-hydroxyquinoline-5-sulfonic acid (H2L1) and 4-amino antipyrene. The structure of the new azo ligand, 7-azo(-4-antipyrene)-8-hydroxyquinoline-5-sulfonic acid (H2L2), was confirmed by various physico-chemical techniques. The molecular structures of H2L1 and its azo derivative (H2L2) were optimized theoretically and the quantum chemical parameters were calculated. Molecular docking was used to predict the efficiency of binding between each ligand and the breast cancer mutant receptor (3hb5-Oxidoreductase). The acid dissociation constants (pKH) of H2L1 and H2L2 ligands have been determined potentiometrically at different temperatures. The stability constants (log K) of some transition metal ions (Mn2+, Co2+, Ni2+ and Cu2+) with the investigated ligands have been determined. The effect of the azo group on both, the dissociation constants of H2L2 ligand and the stability constants of its complexes has been discussed. The thermodynamic parameters (ΔG, ΔH and ΔS) were derived and discussed at different temperatures. The formation of the metal complexes was found to be spontaneous, endothermic and entropically favorable. The relationships between the stability constants and ΔG values of all investigated complexes and their ionic radii have been discussed and correlated.