Liquid crystalline properties of unsymmetrical bent-core compounds containing chiral moieties
作者:R. Amaranatha Reddy、B. K. Sadashiva、U. Baumeister
DOI:10.1039/b419479a
日期:——
The synthesis, characterization and mesomorphic properties of new unsymmetrical bent-core compounds containing chiral moieties are reported. These compounds have been derived from either 3-hydroxybenzoic acid or 2,7-dihydroxynaphthalene as the central unit. The chiral group is incorporated either within the bent-core structure as a linking group or is appended in the terminal position. The influence of the position of the chiral moiety on the mesomorphic properties has been investigated. The bent-core compounds containing a chiral group (octan-2-ol) in the terminal chain exhibit a direct transition from chiral calamitic phases such as SmC*, SmC*γ to a polar banana phase with a two-dimensional lattice (ColobPA*) on decreasing temperature. In order to prove this phase sequence, the corresponding compound with a racemic octan-2-ol group at the terminal chain has been synthesized. The preliminary observations and investigations are presented for comparison with the chiral compound. Possible explanations for this unusual phase sequence and the models for the ColobPA*
(SmSPA*) phase are also discussed on the basis of X-ray and electric field experiments.
报告了含有手性分子的新型非对称弯曲核化合物的合成、表征和介形性质。这些化合物以 3-羟基苯甲酸或 2,7-二羟基萘为中心单元。手性基团或作为连接基团加入到弯曲核心结构中,或附加在末端位置。我们研究了手性基团的位置对介形性质的影响。在末端链中含有手性基团(辛烷-2-醇)的弯曲核化合物表现出随着温度的降低,从手性钙钛矿相(如 SmC*、SmC*γ)直接过渡到具有二维晶格的极性香蕉相(ColobPA*)。为了证明这一相序,我们合成了末端链上带有外消旋辛烷-2-醇基团的相应化合物。初步观察和研究结果与手性化合物进行了比较。在 X 射线和电场实验的基础上,还讨论了这种不寻常相序的可能解释以及 ColobPA* (SmSPA*) 相的模型。