无机-有机杂化树枝状香蕉形液晶化合物的合成与表征

SYNTHESIS AND CHARACTERIZATION OF AN INORGANIC-ORGANIC HYBRID BENT-CORE LIQUID CRYSTAL WITH A CUBIC SILSESQUIOXANE CORE

利用硅氢加成反应制备得到8个香蕉形液晶基元尾接于六面体倍半硅氧烷的8个顶点之上的杂化树枝状香蕉形液晶化合物.此化合物的化学结构通过核磁、红外、元素分析和GPC表征.一维和二维X-射线衍射研究表明,该化合物具有两个双层近晶C相;对样品施加三角波电压后显示该化合物具有反铁电性.

An organic-inorganic hybrid bent-core liquid crystal （BCLC） with eight bent-core mesogens end-attached to inorganic polyhedral oligomeric silsesquioxanes （POSS） cores was synthesized and characterized to study how the inorganic cubic core may affect the liquid crystalline phase behavior and electro-optical properties of the BCLC. POSS-SBC was successfully synthesized by hydrosilylation reaction of Q8M8^H and 3＇-[4-（4-dodecyloxybenzoyloxy）- benzoyloxy]-4-（10-undecen-l-yloxy） benzoyloxybiphenyl with Pt （dvs） as catalyst in high yield. Well-defined chemical structure of POSS-SBC was confirmed by NMR, IR, elemental analysis, and GPC. Liquid crystalline phase behavior of this compound was investigated by differential scanning calorimetry, 1D and 2D wide-angle X-ray diffractions, and small-angle X-ray scattering. Meanwhile, electro-optical characterization was carried out by applying a triangular wave electric field. Response current was measured, and texture change under the electric field was observed. Two bilayer antiferroelectric SmC phases can be confirmed for POSS-SBC. In the higher temperature LC phase,the arrangement of POSS cores in the layer is not ordered. It is a conventional SmCA2 PA phase with layer thickness of 8.0 nm. In the lower temperature LC phase, layer thickness decreases to 7.7 nm. POSS cores from a two-dimensionally ordered structure between two bilayers. It is a bilayer SmCAPA phase with inorganic nano-size mesophase dispersed in it. To our best knowledge, it is the first antiferroelectric LC phase with inorganic nano-size mesophase dispersed in it.