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Photochromism of Diarylethenes with Two Nitronyl Nitroxides: Photoswitching of an Intramolecular Magnetic Interaction
Author(s) -
Matsuda Kenji,
Irie Masahiro
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010817)7:16<3466::aid-chem3466>3.0.co;2-x
Subject(s) - photochromism , chemistry , diarylethene , photochemistry , conjugated system , intramolecular force , nitroxide mediated radical polymerization , radical , benzothiophene , ring (chemistry) , photoisomerization , stereochemistry , polymerization , polymer , isomerization , thiophene , organic chemistry , radical polymerization , catalysis
Photochromic diarylethenes that have p ‐phenylene‐substituted benzothiophene aryl groups with and without nitronyl nitroxide radicals at both ends of the molecules were synthesized. The absorption maxima of the closed‐ring isomers showed a hypsochromic shift with the increase in the π‐conjugated chain length. The unique behavior was attributed to the stabilization by the resonant quinoid structures. Both photocyclization and photocycloreversion quantum yields of the diarylethene with nitronyl nitroxide radicals were found to increase with the increase in the π‐conjugated chain length. Photoswitching of the magnetic interaction between two nitronyl nitroxide radicals was studied by means of ESR spectroscopy. The change in exchange interaction between open‐ and closed‐ring isomers of 1,2‐bis{6‐{4‐[4‐(1‐oxyl‐3‐oxide‐4,4,5,5‐tetramethylimidazolin‐2‐yl)phenyl]phenyl}‐2‐methyl‐1‐benzothiophen‐3‐yl}hexafluorocyclopentene was determined to be more than 30‐fold.