Wang Hao, Tang Yuqi, Krishna Bisoyi Hari, Li Quan
Advanced Materials and Liquid Crystal Institute and Materials Science Graduate Program, Kent State University, Kent, OH 44242, USA.
Institute of Advanced Materials and School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, China.
Angew Chem Int Ed Engl. 2023 Feb 13;62(8):e202216600. doi: 10.1002/anie.202216600. Epub 2023 Jan 9.
A series of macrocyclic azobenzene-based chiral photoswitches have been judiciously designed, synthesized, and characterized. In the molecular structures, binaphthyl is covalently linked to ortho-positions of azobenzene, and four different substituents are linked to 6,6'-positions of binaphthyl. The photoswitches show enhanced helical twisting power (HTP) when doping in commercially available achiral liquid crystals to form self-organized helical superstructures, i.e., cholesteric liquid crystals (CLCs). All the photoswitches exhibit reversible photoisomerization driven by visible light of different wavelengths in both organic solvent and liquid crystals. The photoswitches with shorter substituents enable handedness inversion of CLCs upon photoisomerization. These are the first examples of ortho-linked azobenzene-based photoswitches that enable handedness inversion in CLCs. The photoswitches with longer substituents display only HTP values decreasing while maintaining the same handedness.
一系列基于大环偶氮苯的手性光开关已被精心设计、合成和表征。在分子结构中，联萘共价连接到偶氮苯的邻位，并且四个不同的取代基连接到联萘的6,6'-位。当掺杂到市售的非手性液晶中以形成自组织螺旋超结构，即胆甾相液晶（CLC）时，这些光开关显示出增强的螺旋扭曲能力（HTP）。所有光开关在有机溶剂和液晶中均表现出由不同波长的可见光驱动的可逆光异构化。具有较短取代基的光开关在光异构化时能够使CLC的手性反转。这些是能够使CLC手性反转的邻位连接的偶氮苯基光开关的首个实例。具有较长取代基的光开关仅显示HTP值降低，同时保持相同的手性。
