Charge transfer processes in bilayers and co-polymers composed of C60Pd and 2′-ferrocenylpyrrolidino-[3′,4′;1,2]C60Pd two-component polymers

Abstract

Bilayers composed of fullerene based polymers, C₆₀Pd (n-doped system) and 2′-ferrocenylpyrrolidino-[3′,4′;1,2]C₆₀Pd, Fc-C₆₀Pd, (n- and p-doped system) were prepared by sequential electro-deposition of the parent monomers. The bilayer electrode processes depend upon the polymerization sequence. For the electrode–Fc-C₆₀Pd–C₆₀Pd system, where Fc-C₆₀Pd is initially deposited on the surface and then a layer of C₆₀Pd is deposited, the processes of both fullerene reduction and ferrocene oxidation are observed. The high permeability of the C₆₀Pd film to the ions of the supporting electrolyte allows the oxidation of the inner Fc-C₆₀Pd layer. In the case of the bilayer electrode–C₆₀Pd–Fc-C₆₀Pd, the C₆₀Pd layer is not conductive in the potential range of ferrocene group oxidation. Consequently, the inner C₆₀Pd film inhibits the process of outer layer oxidation. Incorporation of metallic palladium particles into the inner C₆₀Pd layer results in an increase in that film's conductivity. With a C₆₀Pd layer containing metallic palladium particles, the outer Fc-C₆₀Pd layer of the bilayer electrode–C₆₀Pd–Fc-C₆₀Pd can be oxidized at positive potentials. In acetonitrile–toluene containing Pd(ac)₂ and both C₆₀ and Fc-C₆₀, a C₆₀Pd-co-Fc-C₆₀Pd co-polymer is formed during electro-reduction at the electrode surface. This film exhibits redox activity both in the negative and positive potential ranges.