DOI: 10.2478/s11532-007-0035-7 Research article CEJC 5(3) 2007 898–911 Voltammetric and potentiometric studies of some sulpha drug-Schiff base compounds and their metal complexes M.M. Ghoneim 1∗ , E.M. Mabrouk 2 , A.M. Hassanein 1 , M.A. El-Attar 1 , E. A. Hesham 1 1 Electrochemistry research unit, Chemistry Department, Faculty of Science, Tanta University, 31527 Tanta, Egypt 2 Chemistry Department, Faculty of Science, Benha University, 13518 Benha, Egypt Received 30 January 2007; accepted 16 May 2007 Abstract: The electrochemical behavior of some sulpha drug-Schiff bases at a mercury electrode was examined in the Britton-Robinson universal buffer of various pH values (2.5 - 11.7) containing 20% (v/v) of ethanol using DC-polarography, cyclic voltammetry and controlled-potential electrolysis. The DC-polarograms and cyclic voltammograms of the examined compounds exhibited a single, 2-electron, irreversible, diffusion-controlled cathodic step within the entire pH range which is attributed to the reduction of the azomethine group -CH=N- to -CH 2 -NH-. The symmetry transfer coefficient (α) of the electrode reaction and the diffusion coefficient (D 0 ) of the reactant species were determined. The electrode reaction pathway of the compounds at the mercury electrode was suggested to follow the sequence: H + ,e - ,e - ,H + . The dissociation constant of the sulpha drug-Schiff bases, the stability constant and stoichiometry of their complexes with various divalent transition metal ions (Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ ) were determined potentiometrically at room temperature. c  Versita Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved. Keywords: Sulpha drug-Schiff bases, DC-polarography, cyclic voltammetry, potentiometry, metal complexes, dissociation constant, stability constant ∗ E-mail: mmghoneim@usa.net