Cyclic voltammetry of decamethylferrocene at the organic liquid vertical bar aqueous solution vertical bar graphite three-phase junction

Drops of nitrobenzene and 1,2-dichloroethane containing only 0.1 mol l(-1) decamethylferrocene (dmfc) are attached to the surface of a paraffin-impreg nated graphite electrode (PIGE) and immersed into various aqueous electroly tes. The oxidation of dmfc and the reduction of the cation dmfc(+) are enab led by the simultaneous transfers of anions between the aqueous electrolyte and the organic solvents. The reaction starts at the three-phase junction. A linear relationship is observed between the mid-peak potentials of cycli c voltammograms of dmfc and the standard Galvani potential differences of t he anions, and the influence of the anion concentration on the intercepts o f these straight lines is explained. The standard Gibbs energies of transfe r of acetate anions and dmfc(+) cations on the water / nitrobenzene interfa ce are estimated as: DeltaG(tr.Ac-) (0.nb -->w) = -33.4 kJ mol(-1) and Delt aG(tr,dmfe+) (0,nb -->w) =35 +/- 2 kJ mol(-1), respectively. (C) 2001 Elsev ier Science B.V. All rights reserved.