Polarographic Studies of Some Metal(II) Complexes with Cephalosporins Selected from the First Generation

Abstract Both differential pulse polarography and cyclic voltammetry techniques have been applied to investigate the coordination of Cd2+, Zn2+, and Pb2+ ions with some cephalosporins [cephalexin, cefadroxil, and cephaloridine] in unbuffered aqueous medium. Cephalexin exhibits four consecutive complexes with each of Cd2+ and Zn2+ ions are evidenced with increasing ligand concentration, their stoichiometrics 1:1, 1:2, 1:3, and 1:4 metal-to-ligand, respectively, while it forms three complexes only with Pb2+. Also, cefadroxil exhibits four complexes with Cd2+ ions and two only with Pb2+. It appears that, cefadroxil has no complexing properties towards Zn2+ ions. Cephaloridine however, gives four consecutive complexes with Zn2+ only and no complexation occurs with Cd2+ or Pb2+ ions. The reversibility of the electrochemical reaction has been confirmed using cyclic voltammetry. It appears that, the kind of the side chain fixed at the 7-position on the β-lactam ring and the basicity of ligands have influenced on...