Electropolymerization of 2‘-Ferrocenylpyrrolidino-[3‘,4‘;1,2][C₆₀]fullerene in the Presence of Palladium Acetate. Formation of an Electroactive Fullerene-Based Film with a Covalently Attached Redox Probe

This article demonstrates that new redox active films can be electrochemically generated by reduction of a chemically modified fullerene (the ferrocene−fullerene conjugate 2‘-ferrocenylpyrrolidino-[3‘,4‘;1,2][C 60 ]fullerene, Fc-C 60 ) and [Pd(ac) 2 ] 3 . These films are electrochemically active in both positive and negative potential regions. The formation and electrochemical properties of this Fc-C 60 /Pd film have been studied using cyclic voltammetry and electrochemical quartz crystal microbalance techniques. The surface morphology and infrared spectra of the film are also reported. At negative potentials, the electrochemical behavior of the new Fc-C 60 /Pd film shows features similar to the ones displayed for the previously studied C 60 /Pd film. In the positive potential range, peaks related to charge-transfer processes of the ferrocene units linked to the polymer backbone are observed. Reduction of the film at negative potentials is accompanied by transfer of cations at the solution/film interface and their transport inside the solid phase. On the other hand, the transport of the anions is involved in the process of film oxidation. The film exhibits higher permeability to the anions than to the cations. The oxidation process results in significant changes of the structure and morphology of the ferrocenylfullero[C 60 ]pyrrolidine/Pd film. Electrostatic interaction between positively charged ferrocene groups and negatively charged fullerene units within the film significantly modify the redox properties of ferrocene units. The electrochemical properties and the film structure depend also on the concentrations of the precursors in the growth solution.