北京化工大学郭金宝团队报道了卤素键合荧光分子光开关——从三维立方晶格到一维螺旋超结构的转变，用于圆偏振发光的偏振反转。相关研究成果发表在2024年6月10日出版的《德国应用化学》。

能够在圆偏振发光（CPL）信号之间切换的材料的制造既是必要的，也是具有挑战性的。

该文开发了两种新的卤素键合荧光分子光开关，即HB开关1和HB开关2，它们含有不同端基的α-氰基取代的二芳基乙烯化合物。当暴露于特定的紫外线或可见光波长时，它们表现出可控和可逆的Z/E光异构化。当这些开关集成到蓝相液晶（BPLCs）中时，BP的温度范围显著扩大。

值得注意的是，结合HB开关1的BP系统仅在特定的UV/可见光照射下，以及在冷却/加热期间实现了CPL信号的可逆偏振反转。CPL信号的光/热双重响应行为可归因于，由HB开关1的Z/E光异构化和温度变化引起的，从高对称3D BP I晶格到低对称1D螺旋超结构的相变。

该项研究强调了采用卤键组装策略设计具有可切换CPL信号的材料的重要性，为CPL有源系统开辟了新的可能性。

附：英文原文

Title: A Halogen-Bonded Fluorescent Molecular Photoswitch: Transition from 3D Cubic Lattice to 1D Helical Superstructure for Polarization Inversion of Circularly Polarized Luminescence

Author: Shan Li, Jingjing Wang, Meng Tian, Xianyu Meng, Jingxia Wang, Jinbao Guo

Issue&Volume: 2024-06-10

Abstract: The fabrication of materials that can switch between circularly polarized luminescence (CPL) signals is both essential and challenging. Here, two new halogen-bonded fluorescent molecular photoswitches, namely, HB-switch 1 and HB-switch 2, containing α-cyano-substituted diarylethene compounds with different end groups were developed. Upon exposure to specific UV or visible light wavelengths, they exhibited controllable and reversible Z/E photoisomerization. When these switches were integrated into blue-phase liquid crystals (BPLCs), the temperature range of BP significantly expanded. Notably, the BP system incorporating HB-switch 1 exclusively achieved reversible polarization inversion of CPL signals under specific UV/visible light irradiation and during cooling/heating. The photo/thermal dual-response behavior of the CPL signals can be attributed to the phase transition from a high-symmetry 3D BP I lattice to a low-symmetry 1D helical superstructure induced by the Z/E photoisomerization of HB-switch 1 and temperature changes. This study underscores the significance of employing halogen-bond assembly strategies to design materials with switchable CPL signals, opening new possibilities for CPL-active systems.

DOI: 10.1002/anie.202405615

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202405615