Voltammetry of zinc tetraphenylporphyrin in solution and in polymer films: The effect of axial ligands

Abstract

Cyclic voltammetry at Pt electrodes is presented for the title compound in solution with added pyridine or polyvinylpyridine and (C 6H 5) 3P and (C 6H 5) 3As as the well, and in films formed on the electrode from polyvinylpyridine with the porphyrin incorporated by axial ligation. The axial ligands have only a small effect on the one electron reversible oxidaton of the porphyrin but after the second oxidation step, a slow reaction leads to a peripheral nucleophilic substitution whihc is reversed only at much more cathodic voltages (−0.1 V). The substituted form also displays a quasi-reversible reaction at a quite anodic potential (1.0 V) which is rendered unobservable by excess pyridine ligand.