Electrochemical properties of two-component polymers of palladium and pyrrolidine and piperazine derivatives of C60

Redox-active films have been generated via electrochemical reduction in a solution containing palladium(II) acetate and [C-60]fullerene, or derivatives of C-60. The C-60 derivatives include piperazine (piperazine-C-60), pyrrolidine (CH3-pyr-C-60), and a pyrrolidine salt, [(CH3)(2)-pyr-C-60](+) attached to the fullerene unit. In these films, fullerene moieties are covalently bonded to palladium atoms to form a polymeric network. The polymer yields involving the piperazine and pyrrolidine derivatives of C-60 are significantly lower than the yield of the C-60/Pd film. The CH3-pyr-C-60/Pd and [(CH3)(2)-pyr-C-60](+)/Pd films are electrochemically active in the negative potential region due to the reduction of the fullerene moiety. Reduction of the CH3-pyr-C-60/Pd film is accompanied by the transport of supporting electrolyte cations from the solution into the film. In the first reduction step of the [(CH3)(2)-pyr-C-60](+)/Pd film, both cations and anions of the supporting electrolyte are involved. The piperazine-C-60/Pd film exhibits electrochemical activity at both negative and positive potentials. In the negative potential region, reduction of the fullerene cage takes place. Oxidation of the piperazine moiety is responsible for the observed current in the positive potential range. Here, the oxidation process of this polymer is significantly influenced by the presence of metallic palladium particles in the film. (C) 2009 Elsevier Ltd. All rights reserved.