Molecular design of nonchiral bent-core liquid crystals with antiferroelectric properties
Molecular design of nonchiral bent-core liquid crystals with antiferroelectric properties
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DOI：
10.1021/ja993572w
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发表时间：
2000-03-01
影响因子：
15
通讯作者：
Tschierske, C
中科院分区：
文献类型：
--
作者：
Shen, D;Pegenau, A;Tschierske, C
合成了不含希夫碱单元的新型弯核（香蕉形）液晶，并通过偏振光光学显微镜、差示扫描量热法、X射线散射和光电研究进行了研究。这些分子是间苯二酚、3,4'-二羟基联苯和4,4''-二羟基-1,1':3',1''-三联苯的4-(4-烷基苯甲酰氧基)苯甲酸酯和4-(4-烷氧基苯甲酰氧基)苯甲酸酯。根据分子结构和末端烷基链的长度，发现了三种不同的中间相：矩形柱状相、高度有序的低温中间相和反铁电可切换流体近晶中间相（SmCPA）。研究了分子结构对SmCPA相出现的影响。这些分子的自发极化相当高（P-S = 500-700 nC cm(-2)），特别是那些具有长烷基链和短弯核结构的分子具有低熔点和广泛的可转换中间相区域。此外，将描述具有半氟化末端链的反铁电可切换弯核分子的第一实例。
Novel bent-core (banana-shaped) liquid crystals without Schiff-base units have been synthesized and investigated by polarized light optical microscopy, differential scanning calorimetry, X-ray scattering, and electrooptical investigations. These molecules are 4-(4-alkylbenzoyloxy)benzoates and 4-(4-alkoxybenzoyloxy)benzoates of resorcinol, 3,4'-dihydroxybiphenyl, and 4,4"-dihydroxy-1,1':3',1"-terphenyl. Three different mesophases were found depending on the molecular structure and the length of the terminal alkyl chains: a rectangular columnar phase, a highly ordered low-temperature mesophase, and an antiferroelectric switchable fluid smectic mesophase designated as SmCPA. The influence of the molecular structure on the occurrence of the SmCPA phase was investigated. The spontaneous polarization of these molecules is quite high (P-S = 500-700 nC cm(-2)) and specially those molecules with long alkyl chains and short bent-core structures have low melting points and broad regions of this switchable mesophase. Furthermore, first examples of antiferroelectric switchable bent-core molecules with semifluorinated terminal chains will be described.