二元羧酸与4,4′-联吡啶氢键缔合组装主链型超分子液晶

合成了 4 ,4′ 二羧酸 1 ,6 二酚氧基正己烷 ,与等摩尔的 4 ,4′ 联吡啶采用缓慢挥发溶剂的方法组装 ,所得复合体系经DSC分析和偏光显微镜观察表明形成了超分子液晶 ,红外光谱证实了羧基与吡啶基之间氢键的形成

THE MAIN-CHAIN SUPRAMOLECULAR LIQUID CRYSTAL OBTAINED BY HYDROGEN BONDING SELF-ASSEMBLY OF 4,4′-DICARBOXY-1,6-DIPHENOXY HEXANE AND 4,4′-BIPYRIDINE

4,4′-Dicarboxy-1,6-diphenoxy hexane was synthesized,having a m.p. of 303^0℃,and its hydrogen bonding associated complex with equal molar 4,4′-bipyridine exhibited thermally stable supramolecular liquid crystal behavior evidenced by DSC,polarized optical microscopy(POM) and FTIR studies.The DSC transition peak temperatures were 209.5,234.6,246.2℃ in the 2nd heating and 243.2,211.9,173.9℃ in the 1st cooling respectively,and the transition peak temperatures were reproducible during different thermal cycles except a little difference in the first heating.By comparison with the building blocks,the FTIR measurements indicated clearly the formation of strong hydrogen bonding between the carboxyl and pyridyl groups in the complex.The two broad bands at 1883.2 cm -1 and 2441.7 cm -1 were assigned to the stretching vibration of O-H group of the carboxylic acid in the hydrogen-bonded state of carboxyl-pyridyl units.The carbonyl peak of the carboxylic dimer at 1675.1 cm -1 shifted to 1682.9 cm -1 in the spectrum of the complex,and the two peaks 2543.5 cm -1 and 2659.5 cm -1 which were assigned to the Fermi resonance of the carboxylic dimer disappeared.