A ferroelectrically switchable columnar liquid crystal phase with achiral molecules: Superstructures and properties of liquid crystalline ureas
A ferroelectrically switchable columnar liquid crystal phase with achiral molecules: Superstructures and properties of liquid crystalline ureas
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DOI：
10.1021/ja046100c
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发表时间：
2005-03-02
影响因子：
15
通讯作者：
Yamamoto, M
中科院分区：
文献类型：
--
作者：
Kishikawa, K;Nakahara, S;Yamamoto, M
合成了新型柱状液晶化合物N，N '-双（3，4，5-三烷氧基苯基）脲1a-c（R = n-C8 H17，n-C12 H25，n-C16 H33），用差示扫描量热法研究了它们的相变.通过X射线衍射、偏光显微镜和红外光谱对超结构进行了研究。该化合物具有矩形和六方柱状相，其中每一柱中的脲分子以强氢键沿一个方向堆叠。为了确认铁电转换，进行了光电实验，并且1b和1c的六方柱状相响应于所施加的三角波电场（0.1-18 Hz）给出了自发极化的尖锐峰。这是由非手性分子产生的铁电可切换柱状液晶相的第一个例子。
Novel columnar liquid crystalline compounds N,N'-bis(3,4,5-trialkoxylphenyl)ureas 1a-c (R = n-C8H17, n-C12H25, and n-C16H33) were synthesized, and their phase transitions were measured by differential scanning calorimetery. The superstructures were investigated by X-ray diffraction, polarized light optical microscopy, and IR spectroscopy. The compounds exhibited both rectangular and hexagonal columnar phases in which the urea molecules in each column were stacked in one direction with strong hydrogen bonds. To confirm the ferroelectric switching, optoelectronic experiments were carried out, and the hexagonal columnar phases of 1b and 1c gave a sharp peak of spontaneous polarization in response to an applied triangular wave electric field (0.1-18 Hz). This is the first example of ferroelectrically switchable columnar liquid crystal phases generated by achiral molecules.