Solvent dependent photocyclization and photophysics of some 2-ethynylbiphenyls

Frederick D. Lewis, Paul C. Karagiannis, Meledathu C. Sajimon, Katherine S. Lovejoy, Xiaobing Zuo, Michael Rubin, Vladimir Gevorgyan

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Abstract

The spectroscopic properties and photochemical behavior of molecules having 2-ethynylbiphenyl or 2-phenyldiphenylacetylene structures are reported. These molecules undergo photocyclization reactions to yield phenanthrene and dihydrophenanthrene products via putative isophenanthrene (cyclic allene) intermediates. Phenanthrene formation from the isophenanthrene intermediates does not occur via a unimolecular sigmatropic hydrogen shift, but rather by protonation or hydrogen abstraction mechanisms involving the solvent. Cyclization efficiencies are much lower than is the case for previously-investigated 2-vinylbiphenyl systems. The 2-phenyldiphenylacetylenes have high fluorescence quantum yields and long singlet lifetimes when compared to diphenylacetylene. The 2-ethynylbiphenyls decay via a combination of fluorescence and intersystem crossing.

Original languageEnglish (US)
Pages (from-to)369-375
Number of pages7
JournalPhotochemical and Photobiological Sciences
Volume5
Issue number4
DOIs
Publication statusPublished - Jun 5 2006
Externally publishedYes

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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