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Encapsulation‐Controlled Photoisomerization of a Styryl Derivative: Stereoselective Formation of the Anti Z ‐Isomer in the Cucurbit[7]uril Cavity
Author(s) -
Chernikova Ekaterina Y.,
Berdnikova Daria V.,
Peregudov Alexander S.,
Fedorova Olga A.,
Fedorov Yuri V.
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201901095
Subject(s) - photoisomerization , conformational isomerism , chemistry , steric effects , isomerization , cucurbituril , supramolecular chemistry , stereochemistry , stereoselectivity , photostationary state , photochemistry , cis–trans isomerism , crystallography , crystal structure , molecule , organic chemistry , catalysis
The photochemical isomerization of a styrylpyridinium dye ( SP ) bearing an unsymmetrically attached benzo‐15‐crown‐5 ether has been studied in aqueous solution in the absence and presence of cucurbit[7]uril (CB[7]). The detailed analysis of the UV/Vis and NMR spectra showes that the isomeric composition of the photostationary mixtures of SP can be modulated by the host‐guest complexation with CB[7]. It was found that steric hindrance caused by encapsulation of SP in the host cavity induces the exclusive formation of the anti conformer of Z ‐ SP in contrast with the mixture of both anti and syn conformers obtained during photoisomerization of the dye without CB[7]. Remarkably, the displacement of anti Z ‐ SP from CB[7] does not lead to the transformation of the anti Z ‐isomer into the syn Z ‐isomer pointing out the conformational memory of the system. The results provide an interesting example of the supramolecular stereorecognition by the achiral CB[7] host.