Sasaki Haruna, Takanishi Yoichi, Yamamoto Jun, Yoshizawa Atsushi
†Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, 036-8561, Japan.
‡Department of Physics, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto, 605-8502, Japan.
J Phys Chem B. 2015 Mar 26;119(12):4531-8. doi: 10.1021/jp512710r. Epub 2015 Mar 12.
Chirality's effects on physical properties of materials and how chirality arises have persisted as attractive issues in chemistry. We prepared a homologous series of achiral liquid crystal trimers in which three phenylpyrimidine units are connected via flexible heptamethylene spacers. An equimolecular mixture of a trimer with a nematic (N) phase and that with smectic A (SmA), smectic C (SmC), and smectic B phases was found to exhibit an N phase, a SmC phase, and a B4 phase composed of chiral domains with opposite handedness. The chiral characteristics of the B4 phase were confirmed by uncrossing the polarizers in opposite directions. XRD measurements reveal that both SmC and B4 phases have an interdigitated layer structure. That molecular interdigitation might form a supermolecular bent configuration that can produce saddle splay curvature to drive the B4 phase.
手性对材料物理性质的影响以及手性的产生一直是化学领域引人关注的问题。我们制备了一系列同系的非手性液晶三聚体,其中三个苯基嘧啶单元通过柔性七亚甲基间隔基相连。发现一种具有向列相(N相)的三聚体与具有近晶A相(SmA相)、近晶C相(SmC相)和近晶B相的三聚体的等分子混合物呈现出一个N相、一个SmC相以及一个由具有相反手性的手性畴组成的B4相。通过沿相反方向解开偏振器,证实了B4相的手性特征。X射线衍射测量表明,SmC相和B4相均具有交错层结构。分子交错可能形成一种超分子弯曲构型,该构型可产生鞍形展曲曲率以驱动B4相。