Blue phases induced by doping chiral nematic liquid crystals with nonchiral molecules.
Blue phases induced by doping chiral nematic liquid crystals with nonchiral molecules.
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DOI：
10.1103/physreve.68.041710
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发表时间：
2003-10
期刊：
影响因子：
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通讯作者：
M. Nakata;Y. Takanishi;J. Watanabe;H. Takezoe
中科院分区：
文献类型：
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作者：
M. Nakata;Y. Takanishi;J. Watanabe;H. Takezoe
在手性双折射液晶（N* LC）中，当掺杂非手性双折射核液晶（香蕉介晶）时，发现了被认为存在于高手性体系中的蓝相I和II的出现。通过加入外消旋4-（1-甲基庚基氧基羰基）苯基4 '-辛氧基联苯-4-甲酸酯（MHPOBC）也观察到相同的效果，而非手性N-双（对丁基苯胺）（TBBA）无效。这种差异归因于不同的构象，即，已知MHPOBC具有弯曲形状，但TBBA没有。对于香蕉介晶和MHPOBC，掺杂效应在具有较高手性含量的N* LC中更为显著。这种不寻常的掺杂效应归因于客体分子和手性主体分子的手性构象之间的选择性手性相互作用和/或添加的手性客体分子的表面弹性常数的降低。
The emergence of the blue phases I and II that are thought to exist in highly chiral systems has been found in chiral nematic liquid crystals (N* LCs) when they are doped with achiral bent-core liquid crystals (banana mesogens). The same effect was also observed by adding racemic 4-(1-methylheptyl oxycarbonyl)phenyl 4'-octyloxybiphenyl-4-carboxylate (MHPOBC), while achiral terephthal-bis(p-butylaniline) (TBBA) was not effective. The difference was attributed to the different conformations, i.e., MHPOBC is known to have a bent shape, but not TBBA. The doping effect is more remarkable in N* LCs with higher chiral content for both banana mesogens and MHPOBC. This unusual doping effect was attributed to selective chiral interaction between the chiral conformers of guest molecules and chiral host molecules and/or the decrease of the surface elastic constant on adding bent-shaped guest molecules.