Aggregation-induced emission and thermally activated delayed fluorescence of 2,6-diaminobenzophenones

作     者：Masaki Shimizu Masaki Nakatani Kenta Nishimura 

作者机构：Faculty of Molecular Chemistry and Engineering Kyoto Institute of Technology 

出 版 物：《Science China Chemistry》 (中国科学（化学英文版）)

年 卷 期：2018年第61卷第8期

页      面：925-931页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学] 

基　　金：supported by Grants-in-Aid for JSPS KAKENHI (15H03795) MEXT KAKENHI 15K13671 the Nagase Science and Technology Foundation the Ogasawara Foundation for the Promotion of Science and Engineering 

主　　题：donor-acceptor system delayed fluorescence temperature sensor 

摘      要：Exploration of novel organic luminophores that exhibit thermally activated delayed fluorescence(TADF) in the aggregated state is very crucial for advance of delayed luminescence-based applications such as time-gated bio-sensing and temperature *** report herein that synthesis, photophysical properties, molecular and crystal structures, and theoretical calculations of 2,6-bis(diarylamino)benzophenones. Absorption spectra in solution and calculations using density functional theory(DFT) method revealed that the optical excitation took place through intramolecular charge-transfer from one diarylamino moiety to an aroyl group. While the benzophenones did not luminesce in solution, the solids of the benzophenones emitted green light with moderate-to-good quantum yields. Thus, the benzophenones exhibit aggregation-induced emission. Based on the lifetime measurement, the green emission of the solids was found to include TADF. The emergence of the TADF is supported by the small energy gap between the excited singlet and triplet states, which was estimated by time-dependent DFT calculations. Thin films of poly(methyl methacrylate) doped by the benzophenones also showed green prompt and delayed fluorescence whose lifetimes were in the order of microseconds. Linear correlation between logarithm value of TADF lifetime and temperature was observed with the benzophenone in powder, suggesting that the benzophenones can serve as molecular thermometers workable under aqueous conditions.