Columnar liquid-crystalline imidazolium salts. Effects of anions and cations on mesomorphic properties and ionic conductivity
Columnar liquid-crystalline imidazolium salts. Effects of anions and cations on mesomorphic properties and ionic conductivity
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DOI：
10.1246/bcsj.80.1836
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发表时间：
2007-09-15
影响因子：
4
通讯作者：
Kato, Takashi
中科院分区：
文献类型：
--
作者：
Yoshio, Masafumi;Ichikawa, Takahiro;Kato, Takashi
合成了两个系列的1-甲基-3-[3，4，5-三（烷氧基）苄基]咪唑盐（1（n/X-）; n = 8，12，16和18）和1，2-二甲基-3-[3，4，5-三（十二烷氧基）苄基]咪唑盐（2（12/X-）），它们分别含有四氟硼酸根、六氟磷酸根、三氟甲基磺酸根和双（三氟甲基磺酰亚胺）阴离子（X-）。通过差示扫描量热法、偏光显微镜和X-射线衍射对这些盐的热性质进行了表征。除了1（8/X-）和1（12/ X-）含有CF_3SO_3_2和（CF_3SO_2）（2）N-，以及2（12/（CF_3SO_2）2 N-）直接熔融成各向同性离子液体外，其它盐均形成六方柱状液晶相。随着温度的升高，清亮点呈下降趋势。阴离子的大小。用交流阻抗法测定了1（16/X-）形成柱状相的离子电导率。电导率取决于阴离子的性质，这表明主要的导电机制是跳跃和/或扩散的阴离子在柱状结构。
Two series of 1-methyl-3-[3,4,5-tris(alkyloxy)benzyl]imidazolium salts (1(n/X-); n = 8, 12, 16, and 18) and 1,2dimethyl-3-[3,4,5-tris(dodecyloxy)benzyl]imidazolium salts (2(12/X-)) containing anions (X-), such as tetrafluoroborate, hexafluorophosphate, trifluoromethylsulfonate, and bis(trifluoromethylsulfonyl)imide, have been synthesized. The thermal properties of these salts were characterized by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The salts form hexagonal columnar liquid-crystalline phases except for 1(8/X-) and 1(12/ X-) containing CF3SO3_ and (CF3SO2)(2)N-, and 2(12/(CF3SO2)2N-) which melt directly to isotropic ionic liquids. The clearing points show a decreasing trend with an increase in. the size of anions. The ionic conductivities of 1(16/X-) forming columnar phases have been measured by using an alternating current impedance method. The conductivities depend on the nature of anions, suggesting that the predominant conduction mechanism is hopping and/or diffusion of anions in the columnar structures.