In order to examine the liquid crystalline properties of coumain, 3-X- and 7-Y-substituted coumarins where X=cyano and n-alkoxycarbonyl, and Y=4-n-alkyl- and 4-n-alkoxybenzoyl, 4-alkoxycinnamoyloxy, 4′-alkyl- and 4′-alkoxy-4-biphenylylcarbonyloxy, and 4-(4-alkoxybenzoyloxy)benzoyloxy (4) groups have been prepared. The compounds with X=alkoxycarbonyl group tend to exhibit strong smectic properties, and compounds with X=cyano exhibit stable nematic phases, whereas the coumarin core seems to facilitate a lateral separation of molecules in the mesophase due to its large molecular breadth. The heptyloxy homolog of 4 exhibits a reentrant behavior of the C–Nre–SA–N–I type. The thermal properties are discussed in terms of the polarity and polarizability of coumarin, and the molecular structure. The dielectric properties of the compounds have also been examined and discussed in terms of the polarity of the coumarin core.
为了研究
香豆素的液晶特性,我们制备了 3-X 和 7-Y 取代
香豆素,其中 X=
氰基和正烷氧基羰基,Y=4-正烷基和 4-正烷氧基苯甲酰基、4-烷氧基肉桂酰氧基、4′-烷基和 4′-烷氧基-4-
联苯基碳酰氧基以及 4-(4-烷氧基苯甲酰基氧基)苯甲酰氧基 (4)。X=烷氧基羰基的化合物往往表现出很强的涂抹性,而 X=
氰基的化合物则表现出稳定的向列相,而
香豆素核心由于分子广度大,似乎有利于介相中分子的横向分离。4 的庚氧基同系物表现出 C-Nre-
SA-N-I 类型的重入行为。从
香豆素的极性和极化性以及分子结构的角度讨论了热性质。此外,还根据
香豆素核心的极性对化合物的介电性能进行了研究和讨论。