Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit
作者:Govindaswamy Shanker、Marko Prehm、Carsten Tschierske
DOI:10.3762/bjoc.8.54
日期:——
dimesogens exhibit broad ranges of cybotactic nematic phases (N(cybA) and N(cybC)), in some cases accompanied by additional mesophases (CybA or SmC) at lower temperature. The combination of the 3,5-diphenyl-1,2,4-oxadiazole unit with one cyanobiphenyl core leads to the removal of tilted smectic and cybotactic nematic phases (SmC, N(cybC)), which are replaced by the nontilted CybA phases and nematic phases composed
三种新型末端连接的ABA-异三聚体和异二聚体,由弯曲的3,5-二苯基-1,2,4-恶二唑中心单元和一或两个棒状4-氰基联苯核或一个2-苯基-1组成,合成了由柔性间隔物连接的 3,4-噻二唑核,并通过光学偏光显微镜 (PM)、差示扫描量热法 (DSC) 和 X 射线衍射 (XRD) 研究了它们的介晶行为。所有 dimesogens 都表现出广泛的细胞内向列相(N(cybA) 和 N(cybC)),在某些情况下,在较低温度下还伴有额外的中间相(CybA 或 SmC)。3,5-二苯基-1,2,4-恶二唑单元与一个氰基联苯核的组合导致倾斜的近晶相和胞内相向列相(SmC,N(cybC))的去除,它们被非倾斜的 CybA 相和由 SmA 型簇 (N(cybA)) 组成的向列相取代。弯曲核介晶的正交晶胞向列相对于实现正交型双轴向列相特别感兴趣。XRD 和光学观察区分了正交 (N(cybA)) 和偏斜 (N(cybC))