Regulating the mesogenic properties of imidazolium salts by modifying N^3-substituents  

作　　者：Meng Wang Xu Pan Jian Chen Songyuan Dai 

机构地区：[1]Anhui Electric Power Design Institute [2]Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences [3]Beijing Key Laboratory of Novel Thin Film Solar Cells, North China Electric Power University

出　　处：《Science China(Information Sciences)》2015年第12期1884-1890,共7页中国科学（信息科学）（英文版）

基　　金：supported by the National Basic Research Program of China(2011CBA00700);the National Natural Science Foundation of China(21103197;21273242);China Postdoctoral Science Foundation(2013M540526)

摘　　要：In this study, a series of imidazolium salts with different N^3-substituents（3-position： methyl, vinyl, ethyl, n-propyl, n-butyl）-based ionic-liquid crystals with iodide as counterion（ILCs） are synthesized and characterized, with the aim of regulating the mesogenic properties of imidazolium salts. The imidazolium salts-based ionic-liquid crystals are characterized by thermal analysis, polarized optical microscopy, X-ray powder diffraction, and single-crystalline diffraction. Liquid crystalline phase with a Smectic A phase interdigitated bilayer structure is observed. The mesophase temperature range decreases with the increase of the alkyl chain length of N^3-substituent. While when vinyl is attached to the N^3 position, intermolecular ？-？ interactions are formed in adjacent layers, which exert a positive effect on the formation of mesophase. The layer-spacing of imidazolium salts keeps increasing with the increase of the alkyl chain length attached to both the N^1 and N^3 positions, and gradually decreases with the increasing temperature in liquid crystalline phase. The 1-alkyl-3-vinylimidazolium salt has the smallest layer-spacing, due to the intermolecular π-π interactions between the vinyl and imidazolium rings in adjacent layers.In this study, a series of imidazolium salts with different N^3-substituents（3-position： methyl, vinyl, ethyl, n-propyl, n-butyl）-based ionic-liquid crystals with iodide as counterion（ILCs） are synthesized and characterized, with the aim of regulating the mesogenic properties of imidazolium salts. The imidazolium salts-based ionic-liquid crystals are characterized by thermal analysis, polarized optical microscopy, X-ray powder diffraction, and single-crystalline diffraction. Liquid crystalline phase with a Smectic A phase interdigitated bilayer structure is observed. The mesophase temperature range decreases with the increase of the alkyl chain length of N^3-substituent. While when vinyl is attached to the N^3 position, intermolecular ？-？ interactions are formed in adjacent layers, which exert a positive effect on the formation of mesophase. The layer-spacing of imidazolium salts keeps increasing with the increase of the alkyl chain length attached to both the N^1 and N^3 positions, and gradually decreases with the increasing temperature in liquid crystalline phase. The 1-alkyl-3-vinylimidazolium salt has the smallest layer-spacing, due to the intermolecular π-π interactions between the vinyl and imidazolium rings in adjacent layers.

关 键 词：ionic liquid crystals mesogenic properties REGULATE N3-substituents 

分 类 号：O753.2[理学—晶体学] TQ325.504[化学工程—合成树脂塑料工业]