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Direct Observation of Aggregation‐Induced Emission Mechanism
Author(s) -
Guan Jianxin,
Wei Rong,
Prlj Antonio,
Peng Jie,
Lin KunHan,
Liu Jitian,
Han Han,
Corminboeuf Clémence,
Zhao Dahui,
Yu Zhihao,
Zheng Junrong
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202004318
Subject(s) - conical intersection , tetraphenylethylene , chromophore , chemical physics , excited state , photochemistry , intermolecular force , chemistry , spectroscopy , molecule , photoexcitation , relaxation (psychology) , excitation , polarization (electrochemistry) , aggregation induced emission , fluorescence , atomic physics , psychology , social psychology , physics , organic chemistry , quantum mechanics , electrical engineering , engineering
The mechanism of aggregation‐induced emission, which overcomes the common aggregation‐caused quenching problem in organic optoelectronics, is revealed by monitoring the real time structural evolution and dynamics of electronic excited state with frequency and polarization resolved ultrafast UV/IR spectroscopy and theoretical calculations. The formation of Woodward–Hoffmann cyclic intermediates upon ultraviolet excitation is observed in dilute solutions of tetraphenylethylene and its derivatives but not in their respective solid. The ultrafast cyclization provides an efficient nonradiative relaxation pathway through crossing a conical intersection. Without such a reaction mechanism, the electronic excitation is preserved in the molecular solids and the molecule fluoresces efficiently, aided by the very slow intermolecular charge and energy transfers due to the well separated molecular packing arrangement. The mechanisms can be general for tuning the properties of chromophores in different phases for various important applications.