Liu Jiabao, Gao Xiangyu, Niu Qingyu, Jin Mingyuan, Wang Yijin, Alshahrani Thamraa, Sun He-Lue, Chen Banglin, Li Zhiqiang, Li Peng
School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China.
Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200438, China.
Molecules. 2024 Sep 12;29(18):4335. doi: 10.3390/molecules29184335.
A tetraphenylethylene (TPE) derivative, TPEPhDAT, modified by diaminotriazine (DAT), was prepared by successive Suzuki-Miyaura coupling and ring-closing reactions. This compound exhibits aggregation-induced emission enhancement (AIEE) properties in the DMSO/MeOH system, with a fluorescence emission intensity in the aggregated state that is 5-fold higher than that of its counterpart in a dilute solution. Moreover, the DAT structure of the molecule is a good acceptor of protons; thus, the TPEPhDAT molecule exhibits acid-responsive fluorescence. TPEPhDAT was protonated by trifluoroacetic acid (TFA), leading to fluorescence quenching, which was reversibly restored by treatment with ammonia (on-off switch). Time-dependent density functional theory (TDDFT) computational studies have shown that protonation enhances the electron-withdrawing capacity of the triazine nucleus and reduces the bandgap. The protonated TPEPhDAT conformation became more distorted, and the fluorescence lifetime was attenuated, which may have produced a twisted intramolecular charge transfer (TICT) effect, leading to fluorescence redshift and quenching. MeOH can easily remove the protonated TPEPhDAT, and this acid-induced discoloration and erasable property can be applied in anti-counterfeiting.
一种由二氨基三嗪（DAT）修饰的四苯基乙烯（TPE）衍生物TPEPhDAT，通过连续的铃木-宫浦偶联反应和闭环反应制备而成。该化合物在二甲基亚砜/甲醇体系中表现出聚集诱导发光增强（AIEE）特性，其聚集态的荧光发射强度比稀溶液中的对应物高5倍。此外，分子的DAT结构是良好的质子受体；因此，TPEPhDAT分子表现出酸响应荧光。TPEPhDAT被三氟乙酸（TFA）质子化，导致荧光猝灭，用氨处理后可使其可逆恢复（开-关切换）。含时密度泛函理论（TDDFT）计算研究表明，质子化增强了三嗪核的吸电子能力并减小了带隙。质子化的TPEPhDAT构象变得更加扭曲，荧光寿命衰减，这可能产生了扭曲的分子内电荷转移（TICT）效应，导致荧光红移和猝灭。甲醇可以轻松去除质子化的TPEPhDAT，这种酸致变色和可擦除特性可应用于防伪。
