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

• Published in: Analytical letters Vol. 36; no. 6; pp. 1245 - 1260
• Main Authors: Abdel Gaber, A. A., Ghandour, M.A., El-Said, H. S.
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 05.01.2003; Taylor & Francis
• Subjects: Analytical chemistry; Cephalosporins; Chemistry; Complexes; Electrochemical methods; Exact sciences and technology; Polarography; Chemical analysis; Electrochemical method; Association constant; Organic ligand; Stability constant; Lead Complexes; Transition metal Complexes; Complexes; Cyclic voltammetry; Cephalosporin derivatives; Pulse polarography; Multicomponent analysis; Cephalosporins; Polarography; Cadmium Complexes; Chemical properties; Zinc Complexes; Quantitative analysis
• ISSN: 0003-2719; 1532-236X
• DOI: 10.1081/AL-120020156

Both differential pulse polarography and cyclic voltammetry techniques have been applied to investigate the coordination of Cd 2+ , Zn 2+ , and Pb 2+ ions with some cephalosporins [cephalexin, cefadroxil, and cephaloridine] in unbuffered aqueous medium. Cephalexin exhibits four consecutive complexes with each of Cd 2+ and Zn 2+ 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 Pb 2+ . Also, cefadroxil exhibits four complexes with Cd 2+ ions and two only with Pb 2+ . It appears that, cefadroxil has no complexing properties towards Zn 2+ ions. Cephaloridine however, gives four consecutive complexes with Zn 2+ only and no complexation occurs with Cd 2+ or Pb 2+ 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 the complexation reaction as illustrated by the different behaviour of the investigated ligands. The stability constants of the intermediates of the formed complexes were calculated.