Circular dichroism studies of complexation of antibiotic (+)-cephradine with Cr(III), Co(II)and Ni(II) in methanol: Water (80:20)solution

Abstract

Circular dichroism (CD) studies have been utilized to investigate complexation of antibiotic (+)-cephardine with Cr(III), Co(II) and Ni(II) ions in methanol: water (80:20 v/v) solution. The optimum conditions of pH, stoichiometry and time for achieving equilibrium for maximum complexation in these systems are determined. The CD spectra of these complex ions consist of 2-3 Cotton bands between 16,129-25,994 $cm^-1$ with differential absorptivity 0.0046-0.428 deg. L $mol^-1$ $cm^-1$ and bands are assigned to electronic transitions. The formation constants of these complexes in mixed solvent are reported. Key words: CD studies, (+)-cephardine, Chromium (III)-(+)- ceph. complex, Cobalt (II)-(+)-ceph. complex, Nickel (II)-(+)-ceph. complex, Stability constants.