NMR Determination of the Diffusion Mechanisms in Triethylamine-Based Protic Ionic Liquids
NMR Determination of the Diffusion Mechanisms in Triethylamine-Based Protic Ionic Liquids
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DOI：
10.1021/jz200357j
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发表时间：
2011-05-05
影响因子：
5.7
通讯作者：
Holland, Gregory P.
中科院分区：
文献类型：
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作者：
Blanchard, John W.;Belieres, Jean-Philippe;Holland, Gregory P.
质子离子液体（pil）是一种高导电性流体，已成为包括燃料电池在内的电化学应用的替代溶剂。本文采用脉冲场梯度刺激回波（PFG-STE）核磁共振波谱法研究了一组基于三乙胺（TEA）的pls的输运性质，以获得组成每个体系的单个分子种的自扩散系数(D)。我们报告了在两个不同的实验室对由两种不同的合成路线（传统路线和严格无水路线）产生的pil进行的自扩散系数测量。所研究的pll由TEA阳离子和不同阴离子、甲烷磺酸盐（MS）、双（三氟甲基磺酰基）亚胺（TFSI）、四氯铝酸盐（AlCl4-）和双(全氟乙基磺酰亚胺（BETI）组成。与之前的报道相反，本文提出的PFG-STE扩散测量显示，在这些颗粒中没有质子解耦（Grotthuss机制）迁移率。此外，还表明，存在适量的水（类似于1000ppm）可以对酸性质子的D产生显著影响。
Protic ionic liquids (PILs) are highly conductive fluids that have emerged as alternative solvents for electrochemical applications including fuel cells. In the present contribution, the transport properties for a set of triethylamine (TEA)-based PILs were explored with pulsed field gradient stimulated echo (PFG-STE) NMR spectroscopy to obtain the self-diffusion coefficient (D) of the individual molecular species that comprise each system. We report self-diffusion coefficients from measurements conducted in two different laboratories for PILs that were produced by two distinct synthetic routes, a conventional route and a strictly anhydrous route. The PLLs of interest are comprised of TEA cations and different anions, methane sulfonate (MS), bis(trifluoromethylsulfonyl)imide (TFSI), tetrachloroaluminate (AlCl4-), and bis(perfluoroethylsulfonypimide (BETI). In contrast with previous reports, the PFG-STE diffusion measurements presented here show no proton decoupled (Grotthuss mechanism) mobility in these PILs. Additionally, it is shown that the presence of moderate amounts of water (similar to 1000 ppm) can have a marked influence on D of the acidic proton.