Fluorescence and photoinversion reactions in solutions of chiral diaryl sulfoxides with various sizes of aromatic rings

Yasuyuki Tsurutani, Shinjiro MacHida, Kazuyuki Horie, Kawashima Yukio Kawashima, Haruyuki Nakano, Kimihiko Hirao

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Abstract

Chiral aryl 4-tolyl sulfoxides substituted with several sizes of aromatic rings, (S)-(-)-phenyl 4-tolyl sulfoxide (PHSO), (R)-(+)-1-naphthyl 4-tolyl sulfoxide (NASO), (R)-(+)-9-phenanthryl 4-tolyl sulfoxide (PNSO), and (R)-(+)-1-pyrenyl 4-tolyl sulfoxide (PYSO), were prepared. It has turned out for the first time that there are n-σ*, π-σ* and π-π* states in excited states of these molecules by MO calculation. Fluorescence spectra and quantum yields of fluorescence, Φfl, were measured in polar and non-polar solvents. Quantum yields of photoinversion, Φinv, and photolysis, Φdec, were also obtained with CD and HPLC measurements. Aromatic-ketone like characteristics have been noticed in the fluorescence measurements, i.e., fluorescence has been observed from sulfoxides substituted with large aromatic rings and their fluorescence becomes strong in a polar solvent. We attributed these characteristics to the decrease in π-π* transition energy as the degree of conjugation increases, while n-σ* and π-σ* transition energy does not decrease so much. The values of Φinv and Φdec for PHSO, NASO and PNSO were found to be 0.3-0.4 (Φinv) and 0.03-0.05 (Φdec). The quantum yields for PYSO were measured as Φinv = 0.02-0.03 in methanol and hexane, and Φdec = 0.002-0.003 in methanol and 0.012-0.016 in hexane. It was found that quantum yields of photoinversion and photolysis decrease as the π-π* transition energy decreases. We concluded that photoinversion occur during change in electronic states from n-σ* states to the ground state.

Original languageEnglish
Pages (from-to)161-168
Number of pages8
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume122
Issue number3
DOIs
Publication statusPublished - Mar 31 1999
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Physics and Astronomy(all)

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