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Opposite ESIPT characteristic of two AIE-active isomers with different linkage sites

Author:
Dong, Yujie, Shen, Junjie, Li, Weijun, Zhao, Ruiyang, Pan, Yuyu, Song, Qingbao, Zhang, Cheng
Source:
Tetrahedron 2019 v.75 no.18 pp. 2670-2675
ISSN:
0040-4020
Subject:
chemical reactions, imidazoles, isomers, moieties
Abstract:
In this work, we report two isomers composed of 1-phenyl-1H-phenanthro[9,10-d]imidazole (PI), hydroxyl and tetraphenylethylene (TPE), abbreviated as m-PITPE and p-PITPE. It is found that they exhibit similar aggregation-induced emission (AIE) behavior but totally different excited-state intramolecular proton transfer (ESIPT) characteristic, as a result of the different linkage sites of PI on TPE moiety. Theoretical calculations and their different experimental responses to F− demonstrate that only the para-linkage isomer displays ESIPT. In m-PITPE with meta-linkage, the electron cloud distribution only locates at the TPE part in the singlet excited (S1) states, which results in the localized excited state without ESIPT characteristic.
Agid:
6350559