Highly soluble C2v-symmetrical fullerene derivatives: efficient synthesis, characterization, and electrochemical study
Through an efficient octa-substitution reaction, octabromofullerene (C60Br8) was reacted with alcohols or anisole in the presence of silver triflate to produce octaalkoxy and octaaryl fullerenes, respectively, in up to 79% yield with retention of C2v-symmetry. The LUMO level could be widely tuned through the cumulative substituent effects of the eight addends. The difference in LUMO energy level between C60(OCH2CCl3)8 and C60(C6H4-OMe-4)8 was 0.53 eV, representing low-LUMO and high-LUMO fullerenes. Dynamic light scattering measurements revealed that these octa-substituted compounds were dispersed as single molecules both in toluene and in dichloromethane under low-concentration condition. This lack of aggregate formation is attributed to the polar and non-polar hemispheres of these molecules.