| Summary: | A panchromatic light-absorbing [70]fullerene-perylene-BODIPY triad (<b>C<sub>70</sub>-P-B</b>) was synthesized and applied as a heavy atom-free organic triplet photosensitizer for photooxidation. The photophysical processes were comprehensively investigated by the methods of steady-state spectroscopy, time-resolved spectroscopy, as well as theoretical calculations. <b>C<sub>70</sub>-P-B</b> shows a strong absorption ability from 300–620 nm. Efficient cascading intramolecular singlet-singlet energy transfer in <b>C<sub>70</sub>-P-B</b> was confirmed by the luminescence study. The backward triplet excited state energy transfer from C<sub>70</sub> moiety to perylene then occurs to populate <sup>3</sup>perylene*. Thus, the triplet excited states of <b>C<sub>70</sub>-P-B</b> are distributed on both C<sub>70</sub> and perylene moiety with lifetimes of 23 ± 1 μs and 175 ± 17 μs, respectively. <b>C<sub>70</sub>-P-B</b> exhibits excellent photooxidation capacity, and its yield of singlet oxygen reaches 0.82. The photooxidation rate constant of <b>C<sub>70</sub>-P-B</b> is 3.70 times that of <b>C<sub>70</sub>-Boc</b> and 1.58 times that of MB, respectively. The results in this paper are useful for designing efficient heavy atom-free organic triplet photosensitizers for practical application in photovoltaics, photodynamic therapy, etc.
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