Photochemical and photophysical properties of fullerene dendrimers, in which the fullerene-moiety was connected via an acetylene bond with benzyl-ether type dendrons from the second to fourth generation, have been investigated by time-resolved fluorescence and time-resolved absorption methods, in addition to steadystate spectra. The photophysical properties of the dendrimers such as lifetimes of the singlet and triplet excited states were essentially the same, regardless of the dendrimer generation. However, the rate constants of intermolecular processes such as triplet-triplet annihilation, triplet energy transfer, and electron transfer via the triplet states decreased with the increase in dendrimer generation. The relation between the free energy changes and the quenching rate constants revealed long-range electron transfer processes due to steric hindrance of the dendron groups. Furthermore, it was revealed that the solvation of radical ion pairs is also affected by size of the dendron groups. Back electron transfer kinetics became first-order for the electron transfer system of the smaller donor and/or smaller dendron groups, while second-order kinetics was observed for larger donor and/or larger dendron groups. The dendron groups were also found to be effective to keep unstable species such as the chemically generated fullerenyl anion persistent.

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