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Silicon-Phthalocyanine-Cored Fullerene Dendrimers: Synthesis and Prolonged Charge-Separated States with Dendrimer Generations



Silicon-phthalocyanine-cored fullerodendrimers with up to eight fullerene substituents (SiPc–n C60; n=2, 4, and 8) have been synthesized. Photophysical properties of newly synthesized SiPc–n C60 have been investigated by time-resolved fluorescence and transient absorption analysis with pulsed laser light. Laser photolysis measurements suggest the occurrence of a charge-separation process from 1SiPc* to the C60 subunits. The nanosecond transient absorption spectra in the near-IR region indicate that the lifetimes of the formed radical ion pairs are prolonged on the order of SiPc–8 C60>SiPc–4 C60>SiPc–2 C60, which may be related to the electron migration among the C60 subunits. The usefulness of SiPc–n C60 as light-harvesting systems, evaluated as a ratio of the rates of charge recombination to those of charge separation, increases markedly with the dendrimer generation.

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