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首页> 外文期刊>Advanced Functional Materials >Manifestation of a Chiral Smectic C Phase in Diphenylbutadiene-Cored Bolaamphiphilic Sugars
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Manifestation of a Chiral Smectic C Phase in Diphenylbutadiene-Cored Bolaamphiphilic Sugars

机译：二苯丁二烯带芯的两亲糖中手性近晶C相的表现

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摘要

A series of symmetrical bolaamphiphiles possessing a diphenylbutadiene core and glucopyranoside head groups linked together by oligomethylene spacers, were synthesized and their thermotropic liquid crystalline properties investigated by polarized light optical microscopy, differential scanning calorifnetry, X-ray diffraction and electro-optic switching. In spite of the presence of chiral centers, amphiphilic sugars in general do not exhibit macroscopic chirality and this phenomenon is attributed to strong hydrogen bonding between sugar head groups resulting in microphase-segregated layer like arrangements. In the present study all the molecules investigated exhibited the smectic C~* phase, i.e., tilted lamellar phase with macroscopic chiral ordering of the molecules. The stability of this phase increased with increase in the length of the oligomethylene spacers. Whereas for derivatives with spacers containing ≤4 methylene groups, the smectic C~* phase was observed only in the cooling phase, for those containing spacers with ≥5 methylene groups this phase was observed both in the heating and cooling cycles. The absorption and fluorescence spectra of these materials suggest that the unusual observation of macroscopic chirality in these bolaamphiphiles containing free hydroxyl groups could be attributed to self-aggregating behavior of the diphenylbutadiene core.
机译：合成了一系列对称的双亲两亲物，它们具有通过低聚亚甲基间隔基连接在一起的二苯基丁二烯核心和吡喃葡萄糖苷的头基，并通过偏光光学显微镜，差示扫描量热法，X射线衍射和电光转换研究了它们的热致液晶性能。尽管存在手性中心，但两亲性糖通常不表现出宏观手性，并且该现象归因于糖头基团之间的强氢键结合，导致了微相分离的层状排列。在本研究中，所有研究的分子均表现出近晶C〜*相，即具有宏观手性顺序的倾斜层状相。该相的稳定性随着低聚亚甲基间隔基的长度的增加而增加。对于具有间隔基≤4个亚甲基的衍生物，仅在冷却相中观察到近晶C〜*相；对于那些具有间隔基亚甲基≥5的衍生物，在加热和冷却循环中均观察到该相。这些材料的吸收和荧光光谱表明，在这些含有游离羟基的双性两亲物中宏观手性的异常观察可归因于二苯基丁二烯核心的自聚集行为。

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