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通过桥链将2个盘状介晶基元相连,不仅可以稳定盘状液晶柱状相,还有利于玻璃态柱状相的形成,提高盘状液晶作为有机半导体材料的实用性.为此,通过铜盐催化的Eglinton偶联反应合成了8个二乙炔桥连的苯并菲盘状液晶二聚体化合物[C18H6(OCnH2n+1)4(OMe)O2C-C8H16-C≡C-]2,3(n),(n=4~8),[C18H6(OC6H13)5O2C-C8H16-C≡C-]2,(6)和[C18H6(OC6H13)5O-(CH2)m-C≡C-]2,8(m),(m=1,3).差示扫描量热法(DSC)和热台偏光显微镜(POM)对其介晶性进行研究发现:(1)苯并菲周边柔链长度对液晶二聚体化合物的介晶性有影响;(2)二聚体化合物3(n)和6具有玻璃态柱状相,并且所有苯并菲二聚体化合物在降温至-50℃均未出现结晶现象;(3)与二聚体3(6)相比,分子对称性较高的化合物6具有较稳定的柱状相,及较宽的介晶温度范围;(4)连接基、中心桥链的长度和刚性对苯并菲盘状液晶二聚体介晶性有重要影响.
By connecting two discoidal mesogens through bridge chains, not only the columnar liquid crystal phase can be stabilized, but also the glassy columnar phase can be formed and the utility of the disklike liquid crystal as an organic semiconductor material can be improved.Thus, Salt-catalyzed Eglinton coupling reaction of eight diacetylene-bridged triphenylene discotic liquid crystal dimers [C18H6 (OCnH2n + 1) 4 (OMe) O2C-C8H16-C≡C-] C18H6 (OC6H13) 5O2C-C8H16-C≡C-] 2, (6) and [C18H6 (OC6H13) 5O- (CH2) mC≡C-] 2,8 (n = m), (m = 1, 3). The study of their mesogenic properties by differential scanning calorimetry (DSC) and thermal table polarization microscope (POM) (2) dimer compounds 3 (n) and 6 have a glassy columnar phase, and all of the triphenylene dimer compounds did not crystallize after cooling to -50 ° C; (3) Compared with dimer 3 (6), compound 6 with higher molecular symmetry has a more stable columnar phase and a broader mesophase temperature range; (4) The length of the linker, central bridge and The rigidity of the triphenylene discotic liquid crystal dimer has an important influence on the mesomorphism.