摘要/Abstract

弯曲形液晶以其独特的光电性能倍受关注.但目前所报道的弯曲形液晶化合物因其向列相温度范围较窄，相转化温度高，不利于基础与应用研究，发展缓慢.以2，5-二取代-1，3，4-噻二唑为弯曲中心，二氟亚甲氧基（CF₂O）为桥键，直链烷基（n＝5～10，12）为末端链基，设计合成了一系列新型弯曲形液晶化合物.所有目标化合物通过IR、¹H NMR、¹³C NMR、⁹F NMR进行结构表征，并通过差热扫描仪（DSC）和偏光显微镜（POM）对液晶相态进行测定.实验结果表明：所有目标化合物分子，都能呈现较宽的向列相态，最宽达92.74℃（化合物6a）；较之结构相当的噁二唑类弯曲液晶化合物，其熔点稍高，液晶相态的温度范围更宽.为进一步设计合成新型宽温向列相弯曲型液晶提供了素材和理论依据.
关键词: 噻二唑, 二氟亚甲氧基, 弯曲形液晶, 向列相, 合成
Bent-core liquid crystal has attracted much attention because of its unique photoelectric performance. However, the bent-Core liquid crystal has been developed slowly because of its narrow temperature range and high phase transformation temperature. In this paper, a series of novel bent-core liquid crystal compounds were designed and synthesized, which were based on 2, 5-disubstitueted-1, 3, 4-thiadiazole as the central units, difluorooxymethylene (CF₂O) as the linking group and straight alkyl as the terminal chain. The chemical structures of the target compounds were confirmed by IR, ¹H NMR, ¹³C NMR, and ¹⁹F NMR. Then, their transition temperatures and phase textures were investigated by using differential scanning calorimetric (DSC) and polarizing optical microscopy (POM). The result suggested that all the target compounds exhibited nematic phase and existed wide temperature range of nematic phase, and the widest range of nematic phase was 92.74℃. Compared with the structure oxadiazole bend-core liquid crystal, the melting point is slightly higher and liquid crystal phase temperature range is wider, which could provide material and theoretical basis for the further design and synthesis of novel wide-temperature nematic phase bent-core liquid crystal.
Key words: thiadiazole, difluorooxymethylene, bent-core liquid crystal, nematic phase, synthesis


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