ELECTROCHEMISTRY OF CONDUCTING POLYPYRROLE FILMS CONTAINING COBALT PORPHYRIN .2. NEW DEVELOPMENTS AND INCLUSION OF METALLIC AGGREGATES IN THE COORDINATION POLYMER

The electrochemical polymerization of a pyrrole-substituted cobalt porphyrin complex (i.e. 5-(3-(4-(1-pyrrolyl)butyl)phenoxy)-10,15,20-tritolylporphine cobalt) has been performed in acetonitrile + tetrabutylammonium tetrafluoroborate solution. The redox properties of the film were examined by cyclic voltammetry and chronoamperometry. The voltammograms of these films exhibited a reversible process for the Co(II)/Co(I) reaction at a formal potential of -0.90 V (vs. SCE). Using chronoamperometry, quantitative analysis of the curves allowed us to extract the diffusion coefficient D for the Co(II)/Co(I) step of the cobalt porphyrin film, D = 1.46 X 10(-11) cm2 s-1. The cobalt porphyrin content was estimated by cyclic voltammetry, and this shows that thick polymers act as insulators in the low potential range E < -1 V (vs. SCE). Electroreductive inclusion of Pt and Ag aggregates in these coordination polymers from K2PtCl4, H2PtCl6 and AgClO4 solutions was concluded. Evidence that metallic particles were included in the polymer films was provided by scanning electron microscopy coupled with X-ray fluorescence analysis.