Xinhua Cao,Aiping Gao,Haiting Lv,Yan Wu,Xiuxiu Wang,Yang Fan
A new gelator 1 that included m-methyl red was synthesized and fully characterized. It was found that the organogel of 1 was stable in DMSO even if the organogel was stimulated by acid or light. The organogel was thoroughly characterized using various microscopic techniques including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-vis and Fourier transform infrared (FTIR) spectra. The organogel exhibited tunable structures and optical properties under different stimulation. The regular nanoring structure was turned into microspheres after the organogel in DMSO was stimulated at 254 nm light or acid. At the same time, the color of molecule 1 in gel state and solution state was all changed after stimulation by light or acid. The hydrogen bonding and π–π stacking were found to be the main driving forces for gel formation. This dual-responsive gel held promise for soft materials application in upscale smart responsive materials.
Juan Pang,Xincheng Mao,Jialin Xu,Xiang Zhao,Jingyang Kong,Xiaohong Hu
The application of azobenzene (AZO) as a kind of photo-switch is restricted by its excitation source, i.e., 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, m-Methyl Red (m-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 m-MR and m-Methyl Red acrylic anhydride (m-MRAA) as the controls. Compared with m-MR and m-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 cis form and needed more equilibrium time for trans to cis 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.
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