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Photo‐ and Thermal‐Induced Isomerization of Diels–Alder Adducts of Pentacene and TCNE
Author(s) -
Johns Valentine K.,
Shi Zheng,
Hu Wenfang,
Johns Jaime B.,
Zou Shengli,
Liao Yi
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201200195
Subject(s) - isomerization , chemistry , adduct , photochemistry , pentacene , ring (chemistry) , tetracyanoethylene , organic chemistry , catalysis , layer (electronics) , thin film transistor
Herein we report the formation of the second‐ring Diels–Alder adduct together with the central‐ring adduct in a reaction of pentacene and tetracyanoethylene at room temperature. DFT calculations showed that the difference between the free energy of the two isomers is about 3.9 kcal/mol. Photo‐ and thermal‐induced isomerization between the central‐ring adduct and the second‐ring adduct were studied in solution and in polymer films. In solution, the less‐stable second‐ring adduct can be converted into the more‐stable central‐ring adduct either thermally or photochemically, but the reverse transformation does not occur. In a polymer matrix, isomerization can be photochemically induced in both directions at different wavelengths, which results in a photoswitchable system. Formation of pentacene in the photochemical experiments was also observed, which supports an isomerization process involving a photo‐retro‐Diels–Alder reaction.