Highly soluble C2v-symmetrical fullerene derivatives: efficient synthesis, characterization, and electrochemical study

Abstract

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 C_2v-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.