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Room Temperature Reversible Z → E Photoisomerization of Azobenzene Appended to Anthraquinone‐Benzimidazole Based Photoswitches with Resolved n→π* Absorption Band
Author(s) -
Phapale Daulat,
Kushwaha Archana,
Das Dipanwita
Publication year - 2019
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.201900930
Subject(s) - chemistry , azobenzene , photoisomerization , tautomer , isomerization , photochemistry , molecular switch , anthraquinone , hydrogen bond , intermolecular force , solvent effects , imidazole , solvent , molecule , stereochemistry , organic chemistry , catalysis
Light‐triggered substituted azobenzene‐based molecular switches are well known for their potential applications as molecular machines. The Z ‐isomer stability affected by heteroaromatic groups, extended aromaticity, different substituents, and varying the solvents based on their polarity. In this regards, five different anthraquinone/imidazole‐based azobenzene derivatives have been synthesized with different electronic push/pull substituents. The detailed study of photoswitching processes with kinetic data was appraised by using UV/Vis and 1 H‐NMR spectroscopic techniques. The investigation of light‐induced hydroxyl group conversion to quinone‐hydrazone tautomerization has been observed during the isomerization. Most importantly, intermolecular hydrogen bonding interaction between tautomeric form and a higher polar solvent (DMSO) block the isomerization, but in a less polar solvent (DCM), light‐induced trans ↔ cis isomerization takes place by tautomerization pathway with well‐separated π→π* and n→π* transitions. Further, the detailed mechanistic study of solvent‐assisted light‐induced tautomerization with the role of hydrogen bonding and the following WRITE‐READ‐ERASE‐READ system have been derived by using molecular logic gates.