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Electron‐Transfer Reactions Triggered by Uncharged or Cationic Photosensitizer: Methodology for Generation of o ‐Quinodimethane and Analysis of Back Electron‐Transfer Process
Author(s) -
Matsui Yasunori,
Ikeda Teruyo,
Takahashi Yasutake,
Kamata Masaki,
Akagi Megumi,
Ohya Yukako,
Fujino Ryota,
Namai Hayato,
Ohta Eisuke,
Ogaki Takuya,
Miyashi Tsutomu,
TeroKubota Shozo,
Mizuno Kazuhiko,
Ikeda Hiroshi
Publication year - 2017
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201600570
Subject(s) - chemistry , reaction rate constant , photosensitizer , electron transfer , cationic polymerization , marcus theory , photochemistry , nanosecond , electron , kinetic energy , kinetics , organic chemistry , laser , physics , quantum mechanics , optics
Photoinduced electron transfer (PET) followed by back electron transfer (BET) reactions of 1,2‐bis(α‐styryl)benzenes 1 , generates o ‐quinodimethane derivative 2 via the corresponding radical cation 2 ⋅ + . This process serves as a facile method to form o ‐quinodimethane intermediates. The intermediacy of 2 ⋅ + and 2 were confirmed by using various spectroscopic methods and trapping reactions with 3 O 2 and dienophiles. Kinetic analysis using nanosecond time‐resolved absorption showed that 2 ⋅ + was transformed to 2 via a BET process, in which the decay of 2 ⋅ + and rise of 2 have almost the same rate constants of k DECAY =5.6×10 5 s −1 and k RISE =5.9×10 5 s −1 , respectively. The net BET rate constant evaluated by using Marcus theory is much faster than these experimental values, owing to the reduction based on diffusion.