In this paper, we first describe the electrochemical behavior of C 60 and of C70 embedded in films of lipids and cationic amphiphiles on basal-plane pyrolytic graphite (BPG) electrodes in aqueous media. The electrode modifiers used were mainly tridodecylmethylammonium bromide (3C12N+Br-), tetraalkylammonium bromide (4CnN+Br-, n = 5, 6, 7, 8, 10, 12, and 16), and dihexadecyldimethylammonium poly(styrene sulfonate) (2C16N +PSS-). The generated radical monoanions and dianions of C60 and C70 on the electrodes were stable during continuous potential cycling, but the C70 radical monoanion became unstable after the generation of C70.3-, which is not consistent with the behavior of C60. On the basis of the electrolyte dependence, a possible electron-transfer mechanism of fullerenes/lipid (amphiphile)-coated electrodes was presented. Second, a spectroelectrochemical study was conducted for C60/3C12N+Br --modified electrodes, and the results of simultaneous measurements of current and absorbance changes during potential cycling gave direct evidence of the generation of C60.- in aqueous systems. Third, the strong phase-transition-dependent electrochemistry of fullerenes in the films on electrodes was demonstrated in which 2C16N+PSS- and 4CnN+Br- (n = 10, 12, 16) were used as the lipid and amphiphile matrices, respectively. Finally, chemical generation of fullerene radical anions C60.- and C70 .- using NaaS2O4 as a reducing reagent at lipid thin films containing C60 or C70 was investigated. Visible-near-IR spectra revealed that C60.- and C70.- were chemically produced in cationic lipid films in aqueous media. All results obtained suggest that the charge of the lipid matrix and the hydrophobic microenvironments in the lipid films play an important role in the generation of anions of C60 and C70 in these film states in aqueous media.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry