The hydrosilylation of four isomers of tetra(dimethylsiloxy)tetraphenylcyclotetrasiloxane with (4′-cyanobiphenyl-4-yl)undec-10-enoate in the presence of a platinum catalyst afforded four liquid-crystalline stereoisomers of phenylcyclotetrasiloxane with mesogenic cyanobiphenyl groups. The reaction was performed for the first time. The influence of the spatial structure of the stereoisomers of tetraphenylcyclotetrasiloxanes with mesogenic groups on the formation of the liquid-crystalline state by thermooptical, X-ray diffraction, and calorimetric methods. The temperatures and enthalpies of phase transitions were determined, and their reversibility was shown. Differences in both the textures of melts formed on cooling and the phase state and in interplanar distances were found by optical microscopy and X-ray diffraction methods. Based on these data, the spatial structure of the isomers was concluded to affect the phase composition and type of packing in the liquid-crystalline state.
在
铂催化剂存在下,用(4′-
氰基
联苯-4-基)十一-10-烯酸酯对四(二甲基
硅氧基)四苯基环四
硅氧烷的四种异构体进行氢
硅烷化反应,得到了四种带有中生
氰基
联苯基团的苯基环四
硅氧烷液晶立体异构体。该反应是首次进行。通过热光学、X 射线衍射和量热法研究了带有介源基团的四苯基环四
硅氧烷立体异构体的空间结构对液晶态形成的影响。确定了相变的温度和焓,并显示了其可逆性。通过光学显微镜和 X 射线衍射方法发现了冷却时形成的熔体质地和相态以及平面间距离的差异。根据这些数据,得出了异构体的空间结构会影响液晶态的相组成和堆积类型的结论。