High-efficient luminescence induced by the restriction of benzothiazole group torsion for the HBT-H-H molecule in the aggregate state

Wentian Zhang; Hang Yin; Jie Guo; Xin Zhao; Ying Shi

doi:10.1016/j.saa.2023.123319

High-efficient luminescence induced by the restriction of benzothiazole group torsion for the HBT-H-H molecule in the aggregate state

Spectrochim Acta A Mol Biomol Spectrosc. 2024 Jan 5:304:123319. doi: 10.1016/j.saa.2023.123319. Epub 2023 Sep 1.

Authors

Wentian Zhang¹, Hang Yin², Jie Guo¹, Xin Zhao¹, Ying Shi³

Affiliations

¹ Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China.
² Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China. Electronic address: yinhang@jlu.edu.cn.
³ Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China. Electronic address: shi_ying@jlu.edu.cn.

PMID: 37688882
DOI: 10.1016/j.saa.2023.123319

Abstract

The aggregation-induced emission (AIE) effect has been demonstrated to have great potential application in different areas, from organic electronics to biomedical research and physical process monitoring. In general, molecules with AIE characteristic exhibit fluorescence enhancement in the aggregated state by restricting intramolecular motion consumption. The combination of AIE and excited-state intramolecular proton transfer (ESIPT) is meaningful for promoting luminescence. Recently, HBT-H-H molecule, as a derivative of 2-(2-Hydroxyphenyl)benzothiazole (HBT), has drawn extensive attention from researchers. The molecule possesses the intramolecular hydrogen bonding structure which has the potential for ESIPT. Moreover, the fluorescence quantum yield of HBT-H-H in the aggregation state is 35 times higher than that in Toluene. However, the interplay between excited state dynamics and the AIE effect for this molecule is not clear. Especially, how does AIE effect beat non-radiative transition channel by affecting motions of molecular structure. Herein, we investigated the excited state dynamics of HBT-H-H molecule by the spin-flip time-dependent density functional theory and QM/MM method. We found that the molecule relaxes to the conical intersection region through the twisting motion of the benzothiazole group in Toluene solvent. While the AIE effect effectively inhibits this process by preventing the torsion of benzothiazole group, which induces the emission enhancement. The interplay between the excited-state dynamics and AIE effect for the HBT-H-H molecule delineated in this work not only benefits the deep understanding of molecular behavior to the aggregate level, but also provides a guide for the synthesis of AIE materials with favorable performance.

Keywords: Aggregation induced emission; Bon-Oppenheimer molecular dynamics; Conical intersection; Spin-flip time-dependent density functional theory; Spin-orbit coupling.