FLUORESCENCE OF FULLERENE DERIVATIVES AT ROOM-TEMPERATURE

The absorption and fluorescence spectral properties of fullerene (C-60) and its derivatives C60C4H6, C60C5H6, C(60)CHCO(2)Et, and C(60)NCO(2)Et at room temperature were investigated. Breaking the structural symmetry of C-60 results in enhancing the fluorescence quantum yield 2-3-fold in some derivatives. Thus, the room temperature fluorescence of fullerene compounds could be detected more readily. New absorption bands and altered fluorescence spectra were observed in the derivatives. The Stokes' shifts of the derivatives are small, about 4-5 nm, compared to 68 nm for the parent compound. The time-resolved fluorescence decay study indicates that all four fullerene derivatives have a single fluorescence lifetime of ca. 1.2-1.4 ns, which is about the same as that for C-60 (ca. 1.3 ns). Aliphatic solvents have little influence on the absorption or fluorescence spectral profile except on the extinction coefficient whereas aromatic and polar solvents strongly interact with the fullerene derivatives, causing a peak broadening effect.