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Short‐Circuiting Azobenzene Photoisomerization with Electron‐Donating Substituents and Reactivating the Photochemistry with Chemical Modification
Author(s) -
Bandara H. M. Dhammika,
Cawley Shan,
Gascón José A.,
Burdette Shawn C.
Publication year - 2011
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.201100216
Subject(s) - isomerization , photoisomerization , azobenzene , chemistry , photochemistry , excited state , molecular switch , computational chemistry , molecule , organic chemistry , catalysis , physics , nuclear physics
Azobenzene (AB) undergoes ( E ) → ( Z ) isomerization upon exposure to light. Whereas the light‐induced structural change can be exploited for numerous applications, a second, light‐orthogonal switch would facilitate the development of new uses for AB derivatives. Electron‐donating groups on the AB ring system change not only the absorption wavelengths, but also the isomerization properties. Experimental observations and computational studies suggest that the inclusion of multiple electron‐donating groups can short‐circuit the concerted inversion isomerization mechanism of AB by providing new conical intersections between excited states. This phenomenon has been exploited in a unique AB derivative where the conversion of a phenol into an ester restores the isomerization activity.