SYNTHESIS AND CHARACTERIZATION OF AN INORGANIC-ORGANIC HYBRID BENT-CORE LIQUID CRYSTAL WITH A CUBIC SILSESQUIOXANE CORE
无机-有机杂化树枝状香蕉形液晶化合物的合成与表征

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-8BC was successfully synthesized by hydrosilylation reaction of Q_8MH_8 and 3'-4-(4-dodecyloxybenzoyloxy)-benzoyloxy]-4-(10-undecen-1-yloxy)benzoyloxybiphenyl with Pt(dvs)as catalyst in high yield.Well-defined chemical structure of POSS-8BC 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-8BC.In the higher temperature LC phase,the arrangement of POSS cores in the layer is not ordered.It is a conventional SmC_ A2P_A 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 SmC_AP_A 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.