Trân Hoàn Quân, Kawano Shinichiro, Thielemann Rebecca E, Tanaka Kentaro, Ravoo Bart Jan
Organisch-Chemisches Institut and Center for Soft Nanoscience, Universität Münster, Correnstrasse 36, 48149, Münster, Germany.
Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
Chemistry. 2024 Jan 8;30(2):e202302958. doi: 10.1002/chem.202302958. Epub 2023 Nov 23.
The design of responsive liquid crystals enables a diversity of technological applications. Especially photochromic liquid crystals gained a lot of interest in recent years due to the excellent spatiotemporal control of their phase transitions. In this work we present calamitic light responsive mesogens based on a library of arylazopyrazole photoswitches. These compounds show liquid-crystalline behavior as shown by differential scanning calorimetry, grazing incidence X-ray diffraction and polarized optical microscopy. UV-vis spectroscopy and NMR analysis confirmed the excellent photophysical properties in solution and thin film. Additionally, polarized optical microscopy studies of the pristine compounds show reversible phase transition upon irradiation with light. Moreover, as a dopant in the commercially available liquid crystal 4-cyano-4'-pentylbiphenyl (5CB), the temperature range was reduced to ambient temperatures while preserving the photophysical properties. Remarkably, this co-assembled system shows reversible liquid-crystalline to isotropic phase transition upon irradiation with light of different wavelengths. The spatiotemporal control of the phase transition of the liquid crystals offers opportunities in the development of optical devices.
响应型液晶的设计实现了多种技术应用。特别是光致变色液晶近年来因其相变具有出色的时空控制能力而备受关注。在这项工作中，我们展示了基于一系列芳基偶氮吡唑光开关的棒状光响应液晶基元。这些化合物表现出液晶行为，差示扫描量热法、掠入射X射线衍射和偏光显微镜均证实了这一点。紫外可见光谱和核磁共振分析证实了它们在溶液和薄膜中的优异光物理性质。此外，对原始化合物的偏光显微镜研究表明，光照下会发生可逆的相变。此外，作为市售液晶4-氰基-4'-戊基联苯（5CB）中的掺杂剂，温度范围降低到了环境温度，同时保留了光物理性质。值得注意的是，这种共组装体系在不同波长光照下会发生可逆的液晶相向各向同性相的转变。液晶相变的时空控制为光学器件的开发提供了机遇。
