MECHANISM OF MEDIATION OF THE ELECTROCHEMICAL OXIDATION OF K4FE(CN)(6) AT 4-(2,2'-BIPYRIDYL)]ALKYL)-THIOPHENE)IRON(II)]-FILM MODIFIED ELECTRODES IN AQUEOUS-SOLUTIONS

The kinetics of the electrochemical oxidation of K4Fe(CN)(6) at [4-(2, 2'-bipyridyl)]alkyl}thiophene)iron(II)]-film modified electrodes have been investigated in aqueous solutions, using cyclic voltammetry and r otating disk electrode voltammetry. The retro-electrocatalytic reactio n of the substrate at the polymer-coated electrodes is dependent on th e alkyl chain length between the thiophene and 2,2'-bipyridine moietie s and on the concentration of the substrate. The electrodes coated wit h the films possessing short alkyl chains exhibit more reversible volt ammetric behavior and better catalytic activity to the oxidation of [F e(CN)(6)](4-) species in aqueous solutions compared with those possess ing long alkyl chains. Kinetic parameters, calculated on the basis of modified Levich equations, indicate that under most circumstances the mediated reactions are controlled by the chemical step. Copyright (C) 1995 Elsevier Science Ltd.