In situ spectroscopic investigation of the anodic oxidation of 1,4-dimethoxybenzene at platinum electrodes

The electrooxidation of p-dimethoxybenzene on platinum electrodes in strictly dried acetonitrile solutions was studied by in situ spectroscopic methods (UV-Vis differential reflectance, FT-IR reflectance and electron spin resonance (ESR) spectroscopies). The UV-Vis and IR spectra allowed us to investigate the early stages of polymerization and to monitor the film growth, as a function of the electrode potential and the number of potential cycles. The use of both p- and s-polarized IR radiations allowed us to observe the initial step of formation of the radical-cation and its dimerization at the electrode surface or its diffusion in solution. These observations were corroborated by ESR spectroscopy, which showed clearly the participation of the monomer and oligomer radicals in the electropolymerization process. On the other hand, the monomer concentration is a very important factor for molecular orientation at the electrode surface and formation of the polymer film.