[60]Fullerene-perchlorotriphenylmethide anion triads. Synthesis and study of photoinduced intramolecular electron-transfer processes

For the first time an anionic donor, the perchlorotriphenylmethide anion (PTM^-), has been covalently bonded to C₆₀, generating the C₆₀-(PTM^-)₂ triad that is reversibly oxidized to the corresponding C₆₀-perchlorotriphenylmethyl radical triad C₆₀-(PTM)₂. For the triad C₆₀-(PTM ^-)₂, photoinduced charge-separation can be confirmed to occur via the excited singlet states of the C₆₀ moiety and the PTM anion in polar and nonpolar solvents from quenching of their fluorescence intensities in the region of 700-750 nm and 560-630 nm, respectively. The charge-separation state was confirmed by the nanosecond transient absorption spectra in the visible and near-IR spectral regions. After charge-separation, back electron transfer takes place with a lifetime of about 80 ns. Steady-state concentration of the highly persistent PTM radical was observed after repeated laser light irradiation.