Materials Chemistry

Through-Space Interaction: What, Where and How?

Authors

Abstract

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.

Content

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Supplementary material

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TSI SI JUNKAI LIU