Synthesis and mesomorphic properties of the nematic mesophase benzoxazole derivatives with big twist angle of difluoro-biphenyl unit |
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| Authors: | Qiang Weng Longyan Duan Pei Chen Aiai Gao Xinbing Chen |
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| Institution: | 1. Key Laboratory of Applied Surface and Colloid Chemistry (MOE), Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an, PR China;2. Xi’an Modern Chemistry Research Institute, Xi’an, PR China |
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| Abstract: | Modifying the position and numbers of lateral fluorine substituent is a common method to design and adjust the mesophase of liquid crystal compounds. Here, a series of 2-(2,2?-difluoro-4?-alkoxy-1,1?-biphenyl-4-yl)-5-substituted benzoxazole with both non-polar (H, CH3) and polar (NO2) groups (coded as nPF(2)PF(2)Bx) is synthesised and characterised. All of the compounds show a conspicuous inter-ring twist angle of 38° compared with corresponding reference compounds I and II which are calculated by density functional theory method, and it is interesting to note that the final compounds nPF(2)PF(2)Bx show only nematic mesophase during heating or cooling. Meanwhile, the UV-vis absorption bands and photoluminescence emission peaks both display remarkable blue-shifted. The aforementioned results reveal that lateral difluoro substituents play a key role to stable the nematic mesophase by increasing the dihedral angle of biphenyl. |
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| Keywords: | Lateral difluoro substituent benzoxazole derivatives enantiotropic mesophase liquid crystal properties |
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