A C-60-EMBEDDED ARTIFICIAL BILAYER-MEMBRANE FILM ELECTRODE DEVICE - PHASE-TRANSITION-DEPENDENT ELECTROCHEMISTRY

We describe here regulated electrochemistry of C-60 embedded in a cast film of an artificial lipid, dihexadecyldimethylammonium poly(styrene sulfonate) (1) on an electrode. The X-ray diffraction diagram for a c ast film of C-60/1 (molar ratio, 1/19) showed a diffraction peak at 2 theta = 1.8 degrees, suggesting that the film forms multibilayer struc ture with the molecular layers tilting by 47 degrees from the basal pl ane. Phase-transition temperature for a cast film of 1/C-60 (molar rat io, 1/19) in the presence of water determined by differential scanning calorimetry was 27 degrees C, which was almost identical with that of the single component of 1. At temperatures above the phase transition , a cast film of C-60/1 on a basal plane pyrolytic graphite electrode in aqueous solution gave quasi-reversible two-consecutive one-electron -transfer processes leading to C-60(2-) With the formal potential of E -1(0)' = -0.35 V and E-2(0)' = -0.99 V vs SCE corresponding to C-60/C- 60(.-) and C-60(.-)/C-60(2-), respectively. At temperatures below the phase-transition temperatures, the redox current for the electrode was very small or nondetectable. This temperature dependence was reversib le; that is, temperature-driven ''on-off' switching of C-60 electroche mistry was possible. The observed phenomenon would be applicable to C- 60-derivatives, higher fullerenes, and metallofullerenes. The present study opens possibilities for the construction of fullerene/artificial lipid electrical devices based on the nature of self-organized lipid bilayer membranes.