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Does one‐photon photocyclization of trans ‐diarylethylenes involve adiabatic trans‐to‐cis photoisomerization? potential energy surface calculations for 1‐styrylnaphthalene
Author(s) -
Budyka Mikhayl F.
Publication year - 2012
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.23227
Subject(s) - photoisomerization , isomerization , chemistry , photochemistry , adiabatic process , excited state , potential energy surface , cis–trans isomerism , conformational isomerism , potential energy , branching (polymer chemistry) , stereochemistry , atomic physics , molecule , physics , organic chemistry , thermodynamics , catalysis
Potential energy surface (PES) for 1‐styrylnaphthalene was calculated by PM3 method for the S 0 state and PM3‐CI(2x2) method with configuration interaction for the S 1 state. Scanning PES along both isomerization and cyclization reaction coordinates enabled to reveal the minimum energy path (MEP) with low barriers on the S 1 PES from E ‐isomer to dihydrocyclophotoproduct (DHP). This is consistent with formation of the photocyclization product in one‐photon process during irradiation of E ‐isomer. Additionally, the MEP was found to bypass the coordinate region of Z ‐isomer, i.e. one‐photon E ‐isomer‐to‐DHP photocyclization does not demand participation of the excited Z ‐isomer. Therefore, adiabatic trans‐to‐cis isomerization is likely not an intermediate stage on the E ‐isomer photocyclization pathway, and experimentally observed one‐photon formation of the DHP from the E ‐isomer is likely not an evidence for adiabatic trans‐to‐cis photoisomerization, as it is usually assumed. According to the results obtained, two photochemical reactions of E ‐isomer, photoisomerization to Z ‐isomer and photocyclization to DHP, are not consecutive but parallel reactions with branching at perpendicular conformer on the S 1 PES. © 2012 Wiley Periodicals, Inc.