Electrochemistry of tert-Butylcalix[8]arene-C(60) Films Using a Scanning Electrochemical Microscope-Quartz Crystal Microbalance.

The electrochemical reduction of tert-butylcalix[8]arene-C(60) particle films was studied using the scanning electrochemical microscope combined with a quartz crystal microbalance (QCM) for several electrolytes in MeCN. Complexation of the fullerene within the film results in a negative shift of the peak potential of the first cathodic wave by about 400 mV compared to the reduction of a pure C(60) film. The QCM indicates a mass loss during reduction of the film. Even in electrolytes where C(60) anions normally remain in the surface film, a loss of fullerene electrochemical activity occurs. The complex breaks apart upon reduction of the fullerene center, with the fullerene escaping from the calixarene basket into the MeCN solution, leaving the calixarene as an insoluble film on the electrode surface. These results show that the π electron sharing of the complex is decreased by the additional electron density added to the fullerene by reduction to C(60)(-).