Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Abstract

The fluorescence spectrum and fluorescence quantum yield of C7o were determined in a number of solvents at room temperature. A well resolved fluorescence excitation spectrum, which matches the absorption spectrum, was obtained over a broad wavelength region (250 to 580 nm, in n-hexane). The fluorescence lifetime (627 ps in benzene) was determined, thereby settling the uncertainty about the singlet lifetime of C7o. It is shown that the quenching of the fluorescence by organic electron donors involves both dynamic and static mechanisms. The contribution of the latter is much more pronounced than can be explained from the degree of ground-state charge transfer complexation. Analysis in terms ofa Perrin model indicates that long-range intermolecular electron transfer is important, with a radius of action that increases sharply when the donor oxidation potential is lowered.

Photophysics and Photochemistry of a Water-Soluble C60 Dendrimer: Fluorescence Quenching by Halides and Photoinduced Oxidation of I-

“…Quenching of the singlet excited state has received less attention, [8][9][10] in part owing to the very low fluorescence quantum yield of fullerenes. 11 No studies apparently exist concerning the quenching of the fluorescence of C 60 or of its derivatives.…”

“…11 No studies apparently exist concerning the quenching of the fluorescence of C 60 or of its derivatives. However, the fluorescence quenching of C 70 and C 70 derivatives by different electron donors 8 and by the external heavy-atom effect 9,10 has been reported. This last effect has also been used to obtain phosphorescence spectra of fullerenes and their derivatives.…”

Photophysical Properties of the Ground and Triplet State of Four Multiphenylated [70]Fullerene Compounds

“…This trend is similar to that found for C 70 . [20,21] However, the band positions are quite different for C 70 as can be seen from Table 1. The absorption in the 220 nm region is much stronger for C 70 Ph 8 (181 800 M À1 cm À1 at 228 nm) and C 70 Ph 10 (175 000 M À1 cm À1 at 226 nm) than for C 70 (123 200 M À1 cm À1 at 216 nm).…”

“…The C 70 spectral data (in n-hexane) are displayed for comparison. [20,21] C 70 /n-hexane C 70 Ph 4 /CHX C 70 Ph 6 /CHX C 70 Ph 8 /CHX C 70 Ph 8 /BZ C 70 Ph 10 /CHX C 70 Ph 10 Spielmann et al report the synthesis and UV/Vis spectra of C 70 H 8 and C 70 H 10 . [22] These two compounds have the same cage chromophores as our C 70 Ph 8 and C 70 Ph 10 compounds and consequently exhibit very similar spectral features at wavelengths greater than l 300 nm.…”

The Axial and Equatorial Hydrogen Bonds in the Tetrahydropyran⋅⋅⋅HF Complex

“…[20] Gas mixtures of THP ($ 1 %) and HF ($ 5 %) or DF in He at stagnation pressures in the range 1.5 ± 2 bar were used throughout. The details of the spectrometer have been reported elsewhere.…”