Axial-Bundle Phases - New Modes of 2D, 3D, and Helical Columnar Self-Assembly in Liquid Crystalline Phases of Bolaamphiphiles with Swallow Tail Lateral Chains
Axial-Bundle Phases - New Modes of 2D, 3D, and Helical Columnar Self-Assembly in Liquid Crystalline Phases of Bolaamphiphiles with Swallow Tail Lateral Chains
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DOI：
10.1021/ja110065r
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发表时间：
2011-04-06
影响因子：
15
通讯作者：
Tschierske, Carsten
中科院分区：
文献类型：
--
作者：
Prehm, Marko;Liu, Feng;Tschierske, Carsten
合成了两个系列的由刚性和线性的对三联苯核和两个支链组成的多亲性分子，所述的两个支链由一个氟化和一个非氟化分支或两个氟化分支组成，所述的两个系列的多亲性分子由刚性和线性的对三联苯核和两个末端具有能够形成氢键的极性甘油基团组成，和X射线衍射（XRD）关于它们在热致液晶（LC）相中的自组装。至少在最高温度下，所有分子都形成了柱状晶相。在这些相中，柱由芳香族棒的核和脂肪族壳组成。芳族棒形成束，其被旋转平均并且平行于塔长轴。这种独特的组织结构通过不同的光学和XRD方法得到证明。棒束内的芳香族和甘油基团被分离成交替的片段。取决于温度和分子结构，这种周期性的长程柱间关联可以发生，导致具有菱形R（3）的3D有序LC相。这些束嵌入在侧链的基质中，该基质被分成氟代烷基和富烃区域。在2D柱状相中，氟化区域采取沿六方Voronoi晶胞的边缘沿着延伸的直柱的形式，或者对于具有较高的结晶度的化合物，熔合到包围芳香族核的六方蜂窝。在酵母相上的R（3）中，富氟链优先沿沿着右旋和左旋螺旋缠绕在主芳族柱之间的3，螺旋轴上。
Two series of polyphilic molecules composed of a rigid and linear p-terphenyl core, terminated at both ends with polar glycerol groups capable of hydrogen bonding, and two branched swallow tail-type lateral chains, composed of a fluorinated and a nonfluorinated branch or two fluorinated branches, were synthesized and investigated by differential scanning calorimetry, polarizing microscopy, and X-ray diffraction (XRD) with respect to their self-assembly in thermotropic liquid crystalline (LC) phases. Hexagonal columnar phases were formed by all molecules, at least at the highest temperature. In these phases the columns are composed of a core of aromatic rods and an aliphatic shell. The aromatic rods form bundles which are rotationally averaged and lie parallel to the column long axis. This unique organization is proven by different optical and XRD methods. The aromatic and glycerol groups inside the rod bundles are segregated into alternating segments. Depending on temperature and molecular structure, long-range intercolumnar correlation of this periodicity could take place, leading to a 3D-ordered LC phase with rhombohedral R (3) over barm symmetry. The bundles are embedded in the matrix of the lateral chains, which is divided into fluoroalkyl- and aliphatic-rich regions. In the 2D columnar phase the fluorinated regions take the form of either straight columns running along the edges of the hexagonal Voronoi cells or, for compounds with a higher degree of fluorination, fuse to a hexagonal honeycomb enclosing the aromatic cores. In the R (3) over barm phase the fluorine-rich chains are preferentially found along right- and left-handed helices wound around the 3, screw axes between the main aromatic columns.