Self-oriented polycationic copolymers obtained from bipyridinium meso-substituted-octaethylporphyrins

The anodic oxidation of bipyridinium meso-substituted-octaethylporphyrins leads to the coating of the ITO working electrode by cationic polymeric films. A description of the formation and morphological properties of these conducting films are presented as well as the electrochemical synthesis of the initial porphyrinic subunits used as monomers for the electropolymerization. Polymerization of zinc-10-bipyridinium-octaethyl-porphyrinate (1-Zn) by cyclic scanning in the potential range of −0.9 V to 1.6 V yields a cationic copolymer 1-poly-Zn containing alternated porphyrin and viologen units. 1-poly-Zn appears as coils on atomic force micrographs (AFM), where the spheres look like wire’s reels of 32 nm average size with one hole of ca. 15 nm. Morphological studies with AFM examination reveal that these coils are quasi packed in the same direction. This self “orientation effect” is enhanced in the case of the cationic polymer 2-poly-Zn obtained from monomers bearing two bipyridinium units as substituents in the positions 5 and 10 of 2-Zn (zinc-5,10-dibipyridinium-octaethyl-porphyrinate). The morphologies of 2-poly-Zn and 1-poly-Zn copolymers have been studied and compared by atomic force micrograph (AFM). Electrochemical and UV–vis characteristics are given.