Organic Chemistry, Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Strasse 2, D-06120 Halle, Germany.
J Am Chem Soc. 2011 Apr 6;133(13):4906-16. doi: 10.1021/ja110065r. Epub 2011 Mar 10.
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 ̄3m 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 ̄3m phase the fluorine-rich chains are preferentially found along right- and left-handed helices wound around the 3(1) screw axes between the main aromatic columns.
我们合成了两个系列的多亲性分子，它们由刚性和线性的 p-三联苯核组成，两端带有能够形成氢键的极性甘油基团，还有两个分支的燕尾型侧链，由氟化和非氟化支链或两个氟化支链组成。我们通过差示扫描量热法、偏光显微镜和 X 射线衍射（XRD）研究了它们在热致液晶（LC）相中的自组装情况。所有分子至少在最高温度下都形成了六方柱状相。在这些相中，柱状相由芳香棒的核心和脂肪族壳组成。芳香棒形成束，这些束被旋转平均并平行于柱状长轴排列。这种独特的组织通过不同的光学和 XRD 方法得到了证明。棒束内的芳香族和甘油基团被分隔成交替的段。根据温度和分子结构，这种周期性的长程柱间相关性可能会发生，导致具有菱面体 R ̄3m 对称性的 3D 有序 LC 相。束嵌入在侧链的基质中，侧链基质分为富含氟烷基和富含脂肪族的区域。在二维柱状相中，直柱状氟化物区域沿着六边形 Voronoi 胞的边缘排列，或者对于具有更高氟化度的化合物，它们融合成一个六边形的蜂巢，包围着芳香族核心。在 R ̄3m 相中，富氟链优先沿着右手和左手螺旋缠绕在主芳香族柱之间的 3(1)螺旋轴周围。
