Aqueous Electrochemistry of a C60-Bearing Artificial Lipid Bilayer Membrane Film Immobilized on an Electrode Surface: Thermodynamics for the Binding of Tetraalkylammonium Ion to the Fullerene Anion

Abstract

Thermodynamics for the binding of electrolyte cations, in particular, tetraalkylammonium ions, to the electrogenerated radical anion and the dianion of the fullerene moieties in a molecular-bilayer membrane film of C60-bearing artificial lipid, 1, cast on an electrode surface was described. The theoretical treatment predicts a linear relationship between the half-wave potential (E1/2) for the electrode reaction and electrolyte concentration in the film (c) at higher concentrations and enables us to obtain the number of bound cation and binding constant, respectively, from the slope and intercept of the E1/2−ln c plot. We measured differential pulse voltammograms for a cast film of 1 on a basal plane graphite electrode in aqueous solution containing tetraethylammonium chloride (or tetra-n-butylammonium chloride) + KCl = 0. 5 M and found that E1/2−ln cs plots for the modified electrodes are linear in a concentration range of ca. 0.002−0.14 M, where cs is the concentration of ammonium electrolytes in the sol...