Conformational Restriction-Induced Dual Visible Light-Switched Diarylethene Fluorochrome by Composite Films
Guoxing Liu, Changming Tian, Guorong Li, Haifan Zhang, Xinhui Fan, Lijie Liu, Zhanqi Cao, Song Jiang, Xin Zheng, Cao‐Yuan Niu, Xiufang Xu
Abstract
Precise design of photoactive molecules that switch reversibly upon visible-light irradiation is beneficial to develop photosensitive intelligent luminescence materials applied in biological imaging and anticounterfeiting. Herein, we designed a photochromic molecular switch (DAE-BTS) that incorporated cleverly two photoactive groups i.e. diarylethene (DAE) and benzothiazole thiophene styrene (T-BTS) via a π-extended conjugation strategy. T-BTS was undoubtedly identified as a new photo/thermo-controlled molecular switch through some standard characterizations in this work. Interestingly, when T-BTS was connected to the DAE skeleton, its photo/thermos-isomerization activation was restrained. On the contrary, incorporation of two T-BTS sections into the DAE skeleton did not affect photochromism of DAE. Hence, DAE-BTS not only possessed photochromic distinguishing feature but also maintained aggregation-induced emission enhancement characteristic. Moreover, poly(methyl methacrylate) (PMMA) and polypropylene (PP) were first innovatively integrated to form a solid-state composite film, which can supply adaptive nanopores as accommodations for DAE-BTS. The resultant luminescence film DAE-BTS/PMMA–PP exhibited much stronger solid-state fluorescence than DAE-BTS in only PMMA or PP film. Crucially, the formation of the DAE-BTS/PMMA–PP film drove DAE-BTS from the free rotating state to the restricted rotating state. This conformation-constrained strategy further achieved visible light-induced cyclization reaction of the DAE, and then the solid-state fluorescence switch was reversibly controlled by dual visible light, which might be applied in light-recording and anticounterfeiting. The study provided theoretical guidance to accurately design and prepare visible-light-activated DAE derivatives in both directions and optically modulated photoluminescence materials with excellent performance.