Calorimetric Study on the Ion Pairing and Aggregation of 1-Ethyl-3-Methylimidazolium bis(trifluoromethylsulfonyl)amide ([C2mim][NTf2]) and Related Ionic Liquids in the Low-Dielectric Constant Solvent Chloroform
Calorimetric Study on the Ion Pairing and Aggregation of 1-Ethyl-3-Methylimidazolium bis(trifluoromethylsulfonyl)amide ([C2mim][NTf2]) and Related Ionic Liquids in the Low-Dielectric Constant Solvent Chloroform
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DOI：
10.1007/s10953-013-0082-y
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发表时间：
2013-10
影响因子：
1.2
通讯作者：
N. Scharf;A. Stark;M. Hoffmann
中科院分区：
文献类型：
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作者：
N. Scharf;A. Stark;M. Hoffmann
采用量热法研究了离子液体1-乙基-3-甲基咪唑双（三氟甲磺酰基）酰胺（[C2mim][NTf 2]）、1-己基-3-甲基咪唑双（三氟甲磺酰基）酰胺（[C6 mim][NTf 2]）和1-己基-3-甲基咪唑三（三氟甲磺酰基）甲基化物（[C6 mim][CTf 3]）在氯仿（CHCl 3）中的溶解行为，重点研究了[C2mim][NTf 2]的溶解行为.对[C2mim][NTf 2]的量热数据的解释得到了额外的NMR自扩散测量和粘度测量的帮助，这些测量通过斯托克斯-爱因斯坦方程提供了关于存在的物质的平均尺寸的信息。很明显，主要的平衡物种是离子对和聚集体。在288.2 K时，[C2mim][NTf 2]聚集体形成的焓贡献估计为-2.09 kJ/mol添加的IL，在318.2 K时略有下降，为-1.11 kJ·mol− 1。虽然所有三种IL在溶解到CHCl 3中时释放热量，但观察到不同的温度趋势，证明了来自打破IL相互作用的竞争贡献、溶质驻留的空腔形成以及新的溶质-溶剂相互作用的建立的精细平衡。
A calorimetric study of dissolution of the ionic liquids (ILs) 1-ethyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)amide ([C2mim][NTf2]), 1-hexyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)amide ([C6mim][NTf2]), and 1-hexyl-3-methylimidazoliumtris(trifluoromethylsulfonyl)methide ([C6mim][CTf3]) into chloroform (CHCl3) is presented with particular focus on [C2mim][NTf2]. The interpretation of the calorimetric data for [C2mim][NTf2] was aided by additional NMR self-diffusion measurements and viscosity measurements that through the Stokes–Einstein equation provided information about the average size of the species present. It is evident that the main equilibrium species are ion pairs and aggregates. An estimate for the enthalpy contribution from aggregate formation for [C2mim][NTf2] was found to be −2.09 kJ per mol of added IL at 288.2 K and slightly decreasing in magnitude to −1.11 kJ·mol−1at 318.2 K. While all three ILs release heat upon dissolution into CHCl3, different temperature trends are observed demonstrating the fine balance of competing contributions from breaking IL interactions, cavity formation for the solutes to reside in, and the establishment of new solute–solvent interactions.