| Abstract
| - Intramolecular photoinduced charge-separation and charge-recombination processes of a covalently bondedbuckminsterfullerene−diphenylaminofluorene (C60−DPAF) dyad, in which the diphenylaminofluorene moietyis connected to C60 via a ketone group, have been investigated. Quenching of the fluorescence intensities andthe observed short fluorescence lifetimes of the C60 moiety of the dyad in benzonitrile (PhCN) and DMFindicated that charge separation takes place via the singlet excited state of the C60 moiety at a fast rate withhigh efficiency. On the basis of the nanosecond transient absorption spectra, formation of the radical ion pairC60•--DPAF•+ was confirmed in DMF; the radical ion pair decays with a lifetime of 150 ns. From thetemperature dependence of the charge-recombination rate constants, the reorganization energy was evaluatedto be 0.81 eV in DMF, which is reasonably small, characteristic of fullerene derivatives. On the other hand,a mixture of DPAF and C60 showed intermolecular electron transfer via the triplet state of C60 in polar solventssuch as PhCN.
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