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Photophysical Properties of Silyl‐Substituted Stilbene Derivatives
Author(s) -
Maeda Hajime,
Horikoshi Ryo,
Yamaji Minoru,
Furuyama Taniyuki,
Segi Masahito
Publication year - 2020
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.202000397
Subject(s) - chemistry , fluorescence , intramolecular force , photochemistry , photoisomerization , silylation , excited state , absorption (acoustics) , ring (chemistry) , dipole , stereochemistry , organic chemistry , isomerization , physics , quantum mechanics , nuclear physics , acoustics , catalysis
The effects of silyl groups on the structural, absorption, fluorescence, and photoisomerization properties of stilbenes were investigated. In comparison to that of the parent stilbene ( 1 ), fluorescence quantum yields ( Φ f ) of Me 3 Si‐substituted stilbenes 2–4 and 6 in solution were higher. Derivative 5 , in which Me 3 Si groups are present at all ortho positions of the arene moieties, did not fluoresce at room temperature. The absorption and fluorescence wavelength maxima of Me 3 SiMe 2 Si‐substituted stilbene 7 occurred at longer wavelengths compared to those of the Me 3 Si analog 2 . The results of theoretical calculations showed that this difference is a consequence of an increase in the HOMO energy of 7 caused by orbital interaction between π‐system and the σ(Si–Si) orbital. Stilbene 14 , with two Me 3 Si‐C≡C groups at both para positions, had a high Φ f (0.95). The calculated transition dipole moment ( µ ) was well correlated with Φ f . Derivative 21 , which contains Ph 2 N and Me 3 SiC≡C groups exhibited solvatofluorochromism because it possesses a twisted intramolecular charge transfer (TICT) excited state in which the Ph 2 N group and the aromatic ring are orthogonal.