SUBSTITUENT EFFECTS ON THE ELECTROCHEMICAL PROPERTIES OF PYRROLES ANDSMALL OLIGOPYRROLES

The electrochemical oxidation of several oligopyrroles, either unprote cted, partially blocked, or totally blocked on their alpha-terminal po sitions or N-substituted, has been investigated in acetonitrile by cyc lic voltammetry. For all the studied oligopyrroles, reversible voltamm ograms have been obtained at moderate to high scan rates, whereas chem ical evolutions of the cation radicals have been observed at lower sca n rates. The one-electron redox potentials, E degrees, of the oligopyr role/oligopyrrole cation-radical couples have been measured and the Li fetimes of the cation radicals have been estimated. The stabilities of the cation radicals have been examined as a function of the chain len gth and the nature of the substituent.