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Through-Space Interaction: What, Where and How?

preprint
submitted on 07.04.2021, 10:33 and posted on 08.04.2021, 11:09 by Junkai LIU, Haoke Zhang, lianrui hu, jun wang, Jacky W. Y. Lam, Lluís Blancafort, Ben Zhong Tang

Electronic conjugation through covalent bonds is generally considered as the basis for the electronic transition of organic luminescent materials. Tetraphenylethylene (TPE), an efficient fluorophore with aggregation-induced emission (AIE) character, its blue photoluminescence in aggregate state is always ascribed to the through-bond conjugation (TBC) among the four phenyl rings and the central C=C bond. Herein, systematic spectrometry studies and ab initio theoretical simulation were conducted for TPE and its derivatives, and intramolecular through-space interaction (TSI) between two vicinal phenyl rings is proved as the origin of the blue emission. Furthermore, aided by the evaluation of excited-state decay dynamics, the non-luminescent nature of TPE in solution is revealed as the result of excited-state evolution towards conical intersections via isomerization and cyclization. In aggregate state, the excited-state TSI (ESTSI) is stabilized by the restriction of intramolecular motions, and strong blue emission from through-space conjugation is induced. The mechanistic model of ESTSI delineated in this work provides a new strategy to design luminescent materials beyond the traditional theory of TBC, and expands the quantum understanding of molecular behavior into the aggregate level.

History

Email Address of Submitting Author

jliucj@connect.ust.hk

Institution

The Hong Kong University of Science and Technology

Country

Hong Kong, China

ORCID For Submitting Author

0000-0001-5023-0822

Declaration of Conflict of Interest

No conflict of interest

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