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 sym metry of C-60 results in enhancing the fluorescence quantum yield 2-3- fold in some derivatives. Thus, the room temperature fluorescence of f ullerene compounds could be detected more readily. New absorption band s and altered fluorescence spectra were observed in the derivatives. T he Stokes' shifts of the derivatives are small, about 4-5 nm, compared to 68 nm for the parent compound. The time-resolved fluorescence deca y study indicates that all four fullerene derivatives have a single fl uorescence 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 th e absorption or fluorescence spectral profile except on the extinction coefficient whereas aromatic and polar solvents strongly interact wit h the fullerene derivatives, causing a peak broadening effect.