超纯轴手性双咔唑室温磷光 解决咔唑室温磷光来自杂质的难题

Room-Temperature Phosphorescence of Pure Axially Chiral Bicarbazoles

Jintong Song, Yanying Wang, Lang Qu, Lizhi Fang, Xiangge Zhou, Zong-Xiang Xu,* Cheng Yang,* Peng Wu,* and Haifeng Xiang*

J. Phys. Chem. Lett. 2022, 13, 5838−5844

https://doi.org/10.1021/acs.jpclett.2c01614

Ultralong room-temperature phosphorescence (RTP) is greatly important in a series of applications, but obtaining RTP from metal-free organic materials is still an enormous challenge due to the spin-forbidden nature of triplet excitons. Because of its electron-rich nature and easy derivatization, carbazole (Cz) is widely used to build organic RTP and thermally activated delayed fluorescence (TADF) materials. However, Liu et al. (Nat. Mater.2021, 20, 175) recently demonstrated that the RTP of Cz is induced by charge traps of its isomeric impurity in commercial sources. Here, on the basis of the classical El-Sayed rule and the recently discovered intersystem crossing promotion principles (twisted structure and charge transfer), we designed and prepared highly pure (>99.9%) (R/S)-octahydro-binaphthyl-based bicarbazoles (BiCz) for high-performance RTP (ΦP = 23%; τp = 1.09 s). Interestingly, BiCz exhibited photoactivated TADF and RTP in isolated and aggregated states, respectively, and thus would be an efficient tool for rejuvenating Cz-based RTP.