Specialist gelator for ionic liquids
Specialist gelator for ionic liquids
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DOI：
10.1021/la051323h
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发表时间：
2005-11-08
期刊：
影响因子：
3.9
通讯作者：
Shirai, H
中科院分区：
文献类型：
--
作者：
Hanabusa, K;Fukui, H;Shirai, H
由L-天冬酰胺酰-L-苯丙氨酸甲酯制备的环(L-β-3,7-二甲基辛基天冬酰胺酰-L-苯丙氨酰) (1) 和环(L-β-2-乙基己基天冬酰胺酰-L-苯丙氨酰) (2) 被发现是离子液体的专用胶凝剂。它们可以使多种离子液体胶凝，包括咪唑鎓、吡啶鎓、吡唑烷鎓、哌啶鎓、吗啉鎓和铵盐。测定了离子液体在 25 摄氏度下形成凝胶所需的平均最小凝胶浓度 (MGC)。凝胶强度以几乎与添加的胶凝剂浓度成正比的速率增加。以60 g L-1 浓度制备的1-丁基吡啶鎓四氟硼酸盐([C(4)py]BF4)透明凝胶(胶凝剂1/[C(4)py]BF4)的强度为。约1500克厘米(-2)。 FT-IR光谱表明凝胶化的驱动力是酰胺之间的分子间氢键，加热时从凝胶到液体的相变是由氢键的崩溃引起的。由离子液体形成的凝胶具有非常热稳定性；当凝胶以 70 g L-1（胶凝剂/离子液体）浓度制备时，在 140 摄氏度以下不会发生熔化。凝胶的离子电导率与纯离子液体的离子电导率几乎相同。该凝胶剂具有电化学稳定性和宽的电化学窗口。当由含有碳酸亚丙酯的离子液体制备凝胶时，所得凝胶的离子电导率增加到远高于纯离子液体的水平。胶凝剂还使含有支持电解质的离子液体胶凝。
Cyelo(L-beta-3,7-dimethyloctylasparaginyl-L-phenylalanyl) (1) and cyclo(L-beta-2-ethylhexylasparaginyl-Lphenylalanyl) (2), prepared from L-asparaginyl-L-phenylalanine methyl ester, have been found to be specialist gelators for ionic liquids. They can gel a wide variety of ionic liquids, including imizazolium, pyridinium, pyrazolidinium, piperidinium, morpholinium, and ammonium salts. The mean minimum gel concentrations (MGCs) necessary to make gels at 25 degrees C were determined for ionic liquids. The gel strength increased at a rate nearly proportional to the concentration of added gelator. The strength of the transparent gel of 1-butylpyridinium tetrafluoroborate ([C(4)py]BF4), prepared at a concentration of 60 g L-1 (gelator 1/[C(4)py]BF4),was. ca 1500 g cm(-2). FT-IR spectroscopy indicated that a driving force for gelation was intermolecular hydrogen bonding between amides and that the phase transition from gel to liquid upon heating was brought about by the collapse of hydrogen bonding. The gels formed from ionic liquids were very thermally stable; no melting occurs up to 140 degrees C when the gels were prepared at a concentration of 70 g L-1 (gelator/ ionic liquid). The ionic conductivities of the gels were nearly the same as those of pure ionic liquids. The gelator had electrochemical stability and a wide electrochemical window. When the gels were prepared from ionic liquids containing propylene carbonate, the ionic conductivities of the resulting gels increased to levels rather higher than those of pure ionic liquids. The gelators also gelled ionic liquids containing supporting electrolytes.