Syntheses and characterization of novel asymmetric bent-core mesogens exhibiting polar smectic phases
作者:Kinga Gomola、Lingfeng Guo、Surajit Dhara、Yoshio Shimbo、Ewa Gorecka、Damian Pociecha、Jozef Mieczkowski、Hideo Takezoe
DOI:10.1039/b820566c
日期:——
Three series of asymmetric bent-core compounds were synthesized and their mesomorphic properties were studied. All the compounds possess 2-methylresorcinol as a central unit and a stilbene bridge as a main element in the structure. Molecules of series I and series II possess only saturated terminal chains while those of series III have one or both unsaturated chain/s. The mesophases were characterized by using optical polarizing microscopy, differential scanning calorimetry, X-ray diffraction, electrooptic and dielectric measurements, and miscibility studies. All the compounds exhibit the isotropic to SmAPR phase transition and the B1RevTilted phase at lower temperatures. For compounds with one olefinic terminal chain, the temperature range of the SmAPR phase was found to be narrower in comparison to compounds with both saturated terminal chains. A detailed dielectric investigation was carried out on both the SmAPR and B1RevTilted phases and two different types of dynamical behaviour were observed.
合成了三系列非对称弯曲核心化合物,并研究了它们的介晶性质。所有化合物均以2-甲基间苯二酚为中央单元,以二苯乙烯桥为主要结构元素。第一和第二系列的分子仅具有饱和的末端链,而第三系列的分子则有一个或两个不饱和链。通过光学偏振显微镜、差示扫描量热法、X射线衍射、电光和介电测量以及相容性研究,对介晶相进行了表征。所有化合物均展现出各向同性到SmAPR相的转变以及在较低温度下的B1RevTilted相。与双饱和末端链的化合物相比,具有一个烯烃末端链的化合物其SmAPR相的温度范围更窄。详细介电研究表明,SmAPR和B1RevTilted相显示出两种不同类型的动态行为。