| Abstract
| - Photoinduced electron-transfer processes between fullerene (C60) and 1,8-bis(dimethylamino)naphthalene, whichis called a proton-sponge (PS), have been investigated by means of laser flash photolysis in the presence andabsence of CF3CO2H. For a mixture of C60 and PS, the transient absorption spectra showed the rise of theC60 radical anion with concomitant decay of the C60 triplet (3C60*), suggesting that photoinduced intermolecular electron transfer occurs via 3C60* in high efficiency in polar solvent. For a covalently bonded C60−PSdyad, photoinduced intramolecular charge-separation process takes place via the excited singlet state of theC60 moiety, although charge recombination occurs within 10 ns. For both systems, electron-transfer rateswere largely decelerated by addition of a small amount of CF3CO2H, leaving the long-lived 3C60*. Theseobservations indicate that the energy levels for charge-separated states of the protonated PS and C60 becomehigher than the energy level of the 3C60* moiety, showing low donor ability of the protonated PS. Thus,intermolecular electron-transfer process via 3C60* for C60−PS mixture and intramolecular charge-separationprocess via 1C60*−PS for C60−PS dyad were successfully controlled by the combination of the light irradiationwith a small amount of acid.
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