Photonic Switching of Photoinduced Electron Transfer in a Dihydropyrene-Porphyrin-Fullerene Molecular Triad

Paul A. Liddell, Gerdenis Kodis, Joakim Andréasson, Linda De La Garza, Subhajit Bandyopadhyay, Reginald H. Mitchell, Thomas A. Moore, Ana L. Moore, Devens Gust

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Abstract

Photonic control of photoinduced electron transfer has been demonstrated in a dimethyldihydropyrene (DHP) porphyrin (P) fullerene (C60) molecular triad. In the DHP-P-C60 form of the triad, excitation of the porphyrin moiety is followed by photoinduced electron transfer to give a DHP-P.+-C60.- charge-separated state, which evolves by a charge shift reaction to DHP.+-P-60 .-. This final state has a lifetime of 2 μs and is formed in an overall yield of 94%. Visible (≥300 nm) irradiation of the triad leads to photoisomerization of the DHP moiety to the cyclophanediene (CPD). Excitation of the porphyrin moiety of CPD-P-C60 produces a short-lived (<10 ns) CPD-P.+-C60.- state, but charge shift to the CPD moiety does not occur, due to the relatively high oxidation potential of the CPD group. Long-lived charge separation is not observed. Irradiation of CPD-P-C60 with UV (254 nm) light converts the triad back to the DHP form. Thermal interconversion of the DHP and CPD forms is very slow, photochemical cycling is facile, and in the absence of oxygen, many cycles may be performed without substantial degradation. Thus, light is used to switch long-lived photoinduced charge separation on or off. The principles demonstrated by the triad may be useful for the design of molecule-based optoelectronic systems.

Original languageEnglish
Pages (from-to)4803-4811
Number of pages9
JournalJournal of the American Chemical Society
Volume126
Issue number15
DOIs
Publication statusPublished - Apr 21 2004

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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