Calamitic Bolaamphiphiles with (Semi)Perfluorinated Lateral Chains: Polyphilic Block Molecules with New Liquid Crystalline Phase Structures
作者:Xiaohong Cheng、Marko Prehm、Malay Kumar Das、Jens Kain、Ute Baumeister、Siegmar Diele、Dag Leine、Alfred Blume、Carsten Tschierske
DOI:10.1021/ja036213g
日期:2003.9.1
were studied. A wide variety of unique liquid crystalline phases were found upon elongation of the lateral semiperfluorinated chains. For short- and medium-chain length a series of columnar phases were observed, and upon further elongation of the lateral chain a series of novel mesophases with layer structures were found. In the columnar phases, the nonpolar lateral chains segregate into columns, which
作为关键步骤,通过钯催化的交叉偶联反应合成了由刚性联苯单元、两个末端极性 1,2-二醇单元和侧向连接(半)全氟化链组成的新型双亲分子。通过偏光光学显微镜、DSC和X射线散射研究了这些化合物的热致液晶行为,并研究了侧链的长度、数量、结构和位置对介晶性质的影响。在侧向半全氟化链伸长时发现了多种独特的液晶相。对于短链和中链长度,观察到一系列柱状相,并且随着侧链的进一步伸长,发现了一系列具有层状结构的新型中间相。在柱状相中,非极性侧链分离成柱状,这些柱状体嵌入由联苯单元组成的蜂窝状圆柱体网络中。二醇基团的氢键网络串提供保持整体结构的内聚力。改变侧链的长度会影响柱的直径,从而决定包围这些柱所需的联苯单元的数量。这些单位的数量 [4 (c2mm, p4mm)、5 (p2gg)、6 (p6mm)、8 (c2mm) 或 10 (p2gg)] 定义了圆柱体的形状以及柱状相的晶格类型。有人提出,具有 p2gg