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首页> 外文期刊>Chemistry: A European journal >Thermotropic MIDA Boronates as a Case Study for the Role of Dipolar Interactions in Liquid Crystalline Self-Assembly
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Thermotropic MIDA Boronates as a Case Study for the Role of Dipolar Interactions in Liquid Crystalline Self-Assembly

机译：热摩擦硼酸盐作为偶极相互作用在液晶自组装中的作用的案例研究

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摘要

A series of MIDA (N-methylimino diacetic acid) boronates carrying 4-alkoxy, 3,4-bisalkoxy, or 3,4,5-trisalkoxyphenyl substituents were synthesized and their mesomorphic properties characterized by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and Xray diffraction (XRD) techniques such as small- and wideangle X-ray scattering (SAXS and WAXS, respectively). Most derivatives were liquid crystalline. In the case of mono- and bisalkoxy-substituted derivatives, C_6 chains already induced smectic A (SmA) mesophases despite the bulky MIDA head group. With increasing chain length, columnar hexagonal (Col_h) phases replaced SmA phases in the disubstituted series. Quantum chemical calculations on a series of MIDA boronates show that the B-N bond is a dative bond with a positive charge on the boron atom and negative charges on the nitrogen and oxygen atoms. In addition, no p-interaction between the aryl moiety and B-N bond was found, thus the mesogenic unit is electronically decoupled from the MIDA head group. These theoretical findings were supported by IR and Raman spectra as well as by asingle crystal structure analysis of 4-ethoxyphenyl MIDA boronate. Calculations of the electrostatic potential of the MIDA boronate reveal a special polarity pattern that can support the formation of a two-dimensional network and is likely to explain the liquid crystalline self-assembly. The absence of any electronic cross-talk between the MIDA head group and B-aryl or B-alkyl substituents allows the efficient tailoring of the mesophase type through variation of the substituents.
机译：合成了一系列含有4-烷氧基，3,4-双烷氧基或3,4,5-三烷氧基苯基取代基的含量含量（N-甲基氨基甲酸）硼酸盐，其间隔特性以差分扫描量热法（DSC）为特征，偏振光学显微镜（POM）和X射线衍射（XRD）技术，如小型和宽阔的X射线散射（分别）。大多数衍生物是液晶。在单烷氧基取代的衍生物的情况下，尽管庞大的MIDA头组，C_6链已经诱导了近晶的A（SMA）的中间蛋白酶。随着链条长度的增加，柱状六方（COL_H）阶段在二取代的系列中取代了SMA相。在一系列Mida硼酸盐上的量子化学计算表明，B-N键是在硼原子上的正电荷和氮气原子上的负电荷。另外，发现芳基部分和B-N键之间的P型相互作用，因此介晶单元从Mida Head组电子分离。通过IR和拉曼光谱来支持这些理论发现，以及由4-乙氧基苯基Mida硼酸盐的晶体结构分析。 Mida硼酸酯的静电电位的计算揭示了一种特殊的极性图案，可以支持形成二维网络的形成，并且可能解释液晶自组装。没有任何电子串扰的MIDA头组和B-芳基或B-烷基取代基取代基通过取代基的变异允许中间相型有效剪裁。

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