Pang Juan, Mao Xincheng, Xu Jialin, Zhao Xiang, Kong Jingyang, Hu Xiaohong
School of Material Engineering, Jinling Institute of Technology Nanjing 211169 China
RSC Adv. 2020 Sep 23;10(58):35164-35173. doi: 10.1039/d0ra06627c. eCollection 2020 Sep 21.
The application of azobenzene (AZO) as a kind of photo-switch is restricted by its excitation source, , UV light. Hence, visible light-driven azobenzene-based photo-switching is needed and has been designed in the work. In order to forecast the optimal triggered wavelength, the electrostatic potential, theoretical UV-vis spectra, as well as the energy gap for focused structures was calculated to describe the energy and orbit status of the molecules by DFT. According to the theoretical optimization results, -Methyl Red (-MR) containing copolymer was successfully synthesized as a visible light-driven photo-switch. Further, for performance evaluation, the efficiency and effectiveness of different excitation wavelengths was firstly evaluated for the copolymer using -MR and -Methyl Red acrylic anhydride (-MRAA) as the controls. Compared with -MR and -MRAA, the copolymer exhibited outstanding characteristics as a photo-switch according to its response-recovery behavior. At the same time, blue light proved to be the most efficient excitation light source. Moreover, the equilibrium response time and recovery time showed some dependence on the excitation wavelength. Secondly, the influence of the light intensity on the isomerization transition was investigated. A relatively low light density could lead to a relatively low degree of the final form and needed more equilibrium time for to transformation but showed little effect on the recovery process. Thirdly, repeatable on/off irradiation was used to evaluate the fatigue resistance of the copolymer. Good fatigue resistance without photobleaching was verified from the results. Fourthly, the influence of the solvent on visible light-driven isomerization was also evaluated. Finally, the synthesized copolymer still had the characteristic of a pH indicator with a critical point at pH 5.0 and exhibited an obvious fluorescent characteristic.
偶氮苯（AZO）作为一种光开关的应用受到其激发源（紫外光）的限制。因此，需要可见光驱动的基于偶氮苯的光开关，并且在这项工作中已经进行了设计。为了预测最佳触发波长，通过密度泛函理论（DFT）计算了聚焦结构的静电势、理论紫外-可见光谱以及能隙，以描述分子的能量和轨道状态。根据理论优化结果，成功合成了含 -甲基红（-MR）的共聚物作为可见光驱动的光开关。此外，为了进行性能评估，首先以 -MR和 -甲基红丙烯酸酐（-MRAA）为对照，评估了共聚物在不同激发波长下的效率和有效性。与 -MR和 -MRAA相比，根据其响应-恢复行为，该共聚物表现出作为光开关的优异特性。同时，蓝光被证明是最有效的激发光源。此外，平衡响应时间和恢复时间对激发波长有一定依赖性。其次，研究了光强度对异构化转变的影响。相对较低的光密度会导致最终 形式的程度相对较低，并且从 到 的转变需要更多的平衡时间，但对恢复过程影响较小。第三，使用可重复的开/关照射来评估共聚物的抗疲劳性。结果验证了其具有良好的抗疲劳性且无光漂白现象。第四，还评估了溶剂对可见光驱动异构化的影响。最后，合成的共聚物仍具有pH指示剂的特性，临界点在pH 5.0，并且表现出明显的荧光特性。
