Electrochemical Study on the Initial Stages of the Electropolymerization of 1-Pyrenamine in Acetonitrile

Abstract

Abstract The kinetic study of the mechanism for the reaction of the initial stages of the electropolymerization of 1-pyrenamine (PA) in an acetonitrile solution was carried out by cyclic voltammetry (CV) and double potential-step chronoamperometry (DPSCA). The experiments were conducted at various time windows (i.e., at various scan rates of CV and various potential-step widths of DPSCA) and under the conditions of the presence or absence of the basic or acidic additives (pyridine, 2,6-lutidine, trifluoroacetic acid). As a result, it was found that the mechanism of the reaction of the initial stages of the electropolymerization of PA is an “ECE” mechanism, and that the chemical reaction interposed between successive electron transfers is considered as the radical–radical coupling reaction rather than the radical–parent monomer coupling reaction. The second-order rate constant for the radical–radical coupling reaction was estimated to be (1.0±0.8)×105 M−1 s−1 (1 M=1 mol dm−3). The cyclic voltammetric responses for the oxidation of PA were varied by the presence or absence of the basic or acidic additives. This can be explained considering the basicity of the additives and their influences in the deprotonation reactions following the heterogeneous electron transfer step.