Construction of a metallofullerene La@C₈₂/artificial lipid film-modified electrode device and its electron transfer

Functional electrode devices modified with cast films of metallofullerene La@C₈₂-A solely and of metallofullerene-artificial lipids were constructed, and the aqueous electrochemistry of the electrodes was investigated. Tridodecylmethylammonium bromide (1), which forms a multimolecular bilayer membrane structure, was used as the artificial lipid. The electron-transfer reactions of the modified electrodes were examined by means of electrochemical techniques. Almost no electrochemistry was observed for the La@C₈₂-A film-coated electrode. In sharp contrast with this result, a La@C₈₂-A/1-coated electrode was found to exhibit well-defined cyclic voltammograms with major cathodic peak potentials at 0.28, -0.69, and -1.0 V (vs SCE), which would correspond to the first, second, and third reduction of La@C₈₂-A, respectively. The observed cyclic voltammograms were stable for potential cycling. The first reduction process was found to be stable for the negative-end potential hold, while the second and third reduction processes were unstable. The higher stability of the first reduction state of La@C₈₂-A would be due to the formation of a closed shell structure like La@C₈₂-A anion in o-dichlobenzene. La@C₈₂ embedded in the lipid film on the electrode was rather stable for dioxygen.