Through-Space Interaction of Tetraphenylethylene: What, Where, and How

Electronic conjugation through covalent bonds is generally considered as the basis for the electronic transition oforganic luminescent materials. Tetraphenylethylene (TPE), anefficientfluorophore with aggregation-induced emission character,fluoresces blue emission in the aggregate state, and suchphotoluminescenceisalwaysascribedtothethrough-bondconjugation (TBC) among the four phenyl rings and the centralC???C bond. However, in this work, systematic spectroscopicstudies and DFT theoretical simulation reveal that the intra-molecular through-space interaction (TSI) between two vicinalphenyl rings generates the bright blue emission in TPE but not theTBC effect. Furthermore, the evaluation of excited-state decaydynamics suggests the significance of photoinduced isomerizationin the nonradiative decay of TPE in the solution state. More importantly, different from the traditional qualitative description forTSI, the quantitative elucidation of the TSI is realized through the atoms-in-molecules analysis; meanwhile, a theoretical solid-statemodel for TPE and other multirotor systems for studying the electronic configuration is preliminarily established. The mechanisticmodel of TSI delineated in this work provides a new strategy to design luminescent materials beyond the traditional theory of TBCand expands the quantum understanding of molecular behavior to the aggregate level.

Automated summary

This study reveals a new strategy for the luminescence mechanism of tetraphenylethylene, providing a quantitative understanding of the through-space interaction and establishing a theoretical solid-state model, expanding the understanding of molecular behavior.