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In this study the existence of the C60 cation produced by photochemically induced electron transfer in the presence of different sensitising molecules is proved for the first time by using ESR spectroscopy. It is demonstrated for triphenylpyryliumtetrafluoroborate (TPP) by this spectroscopic method that the electron transfer from C60 to TPP occurs without an application of a cosensitiser. Furthermore it is shown that the addition of alcohols causes a new radical in the system C60/TPP. The stationary concentration of the C60 cation diminishes even in the presence of a cosensitiser to such a low concentration that it is not detectable by ESR spectrosopy. The spectroscopic study of the sensitiser/C60 system is also extended to the reaction products.

The electron transfer from tetraethoxyethene (TEOE), which has high electron-donor ability, to photoexcited C 60 or C 70 in polar and less polar solvents has been investigated by 532 nm laser flash photolysis with observation of the transient absorption bands in the near-IR region. The transient absorption bands of the triplet states of fullerenes ( T C 60 * and T C 70 *), which appeared immediately after nanosecond laser exposure, were effectively quenched by TEOE. With the decay of T C 60 * and T C 70 *, the absorption bands of C 60 Ϫ and C 70 Ϫ appeared at 1070 and 1380 nm, respectively, showing that the electron transfer takes place from TEOE to T C 60 * or to T C 70 *. Then, C 60 Ϫ and C 70 Ϫ disappear by back electron transfer to TEOE ϩ .The efficiencies and rates of the electron-transfer reactions vary with solvent polarity.

The photoreactions of 4‐methyl‐1,2,4‐triazoline‐3,5‐dione (NMTAD) with C60 and with several fullerene derivatives have been studied. In general, NMTAD cycloadds to C60 and to its monoadducts with closed structures in a highly regioselective [2+2] fashion at a cis‐1 [6,6] double bond. Cycloadditions to azafulleroids occur by a slightly different pathway and result in partially cluster‐opened bis(adducts). 1,6‐Methano[60]fulleroid, however, also undergoes a [2+2+2] cycloaddition in the absence of light. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Fullerene derivativesFullerene derivatives Q 1145 Functionalization of [60]Fullerene and of [60]Fullerene Monoadducts by Photochemical Cycloaddition of 4-Methyl-1,2,4-triazoline-3,5-dione. -(ULMER, L.; SIEDSCHLAG, C.; MATTAY*, J.; Eur.