HETEROSUPRAMOLECULAR CHEMISTRY - AN APPROACH TO MODULATING FUNCTION IN MOLECULAR DEVICES

Linked viologen-anthraquinone molecules are attached to TiO2 nanocryst allites supported on a conducting glass substrate. The resulting assem bly is incorporated as the working electrode in an electrochemical cel l. Under open-circuit conditions, band-gap excitation of the semicondu ctor nanocrystallite results in viologen-mediated electron transfer to anthraquinone. Prior application of a negative potential step, which results in 2e(-)/2H(+) reduction of anthraquinone, permits electron tr ansfer only to viologen. At positive applied potentials, electron tran sfer following band-gap excitation is largely suppressed. Some implica tions of these findings for modulation of Function in molecular device s are considered.