Mesophase behaviour of 1,2,3-triazole-based nematic liquid crystals influenced by varying alkyl chains and halogen atom substitution
Mesophase behaviour of 1,2,3-triazole-based nematic liquid crystals influenced by varying alkyl chains and halogen atom substitution
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DOI：
10.1080/02678292.2022.2066731
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发表时间：
2022-08
期刊：
影响因子：
2.2
通讯作者：
Dan Xiong;Xiao-Yun Xiong;Z. Chen;Wenhao Yu;C. Feng;Hongmei Chen;Hailiang Ni;Bi-qin Wang;K. Zhao;P. Hu
中科院分区：
文献类型：
--
作者：
Dan Xiong;Xiao-Yun Xiong;Z. Chen;Wenhao Yu;C. Feng;Hongmei Chen;Hailiang Ni;Bi-qin Wang;K. Zhao;P. Hu
为了开发具有光学和光伏器件应用潜力的新型向列相液晶（LC）材料，研究了1,2,3-三唑基化合物中烷基链和卤素原子取代的变化，以及对中间相行为的影响。通过原位活化的串联有氧卤化和咔嗒反应，成功合成了4-（4-丙基环己基）苯基4-（1-烷基-5-氢/卤-1,2,3-三唑-4-基）苯甲酸酯系列1。除5-噻吩-1,2,3-三唑类化合物1c-Th不表现出中相性外，其余化合物1形成对映向列相，其中化合物5-氢-1,2,3-三唑类化合物1c-H （C10）和1d-H (C12)（长直链化合物）形成两种中相（近晶C相和向列相）。对于5-halo-1,2,3-三唑化合物1c-X （x =卤化物），由于卤素原子取代基对三唑的影响，其亚晶温度范围比相应的化合物1c-H更宽。密度泛函理论（DFT）分析表明，以计算得到的二面角、偶极矩、极化率和分子静电势为参数，可以定义c- x (H)系的结构-性质关系。值得注意的是，在1,2,3-三唑的5位上引入卤素原子可以大大拓宽介生温度范围，这是由于这类化合物的分子间力弱和偶极矩大。图形抽象
ABSTRACT To develop novel nematic-phase liquid-crystal (LC) materials with practical potential in optical and photovoltaic devices, the alkyl chain and halogen atom substitution in 1,2,3-triazole-based compounds were varied, and the effects on the mesophase behaviour were investigated. The 4-(4-propylcyclohexyl)phenyl 4-(1-alkyl-5-hydro/halo-1,2,3-triazol-4-yl)benzoate series 1 was successfully synthesised through tandem aerobic oxidative halogenation and click reaction via in situ activation. Except for 5-thiophene-1,2,3-triazole compound 1c-Th displaying no mesomorphism, the other compounds 1 form enantiotropic nematic mesophases, among which compounds 5-hydro-1,2,3-triazole 1c-H (C10) and 1d-H (C12) (long straight chain compounds) form two mesophases (smectic C phase and nematic phase). For 5-halo-1,2,3-triazole compounds 1c-X (× = halide), the mesomorphic temperature range was wider than for the corresponding compound 1c-H because of the effect of the halogen atom substituent on the triazole. Density functional theory (DFT) analysis showed that the structure-property relation for series 1c-X(H) could be defined by using the calculated dihedral angles, dipole moment, polarisability, and molecular electrostatic potential as parameters. Notably, introducing halogen atoms at the 5-position of 1,2,3-triazole can greatly broaden the mesogenic temperature range, ascribed to the weak intermolecular forces and large dipole moment in this class of compounds. GRAPHICAL ABSTRACT