Hydrogen bond in imidazolium based protic and aprotic ionic liquids
Hydrogen bond in imidazolium based protic and aprotic ionic liquids
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DOI：
10.1016/j.molliq.2015.08.005
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发表时间：
2016-05
影响因子：
6
通讯作者：
Hikari Watanabe;Hiroyuki Doi;Soshi Saito;Masaru Matsugami;K. Fujii;R. Kanzaki;Y. Kameda;Y. Umebayashi
中科院分区：
文献类型：
--
作者：
Hikari Watanabe;Hiroyuki Doi;Soshi Saito;Masaru Matsugami;K. Fujii;R. Kanzaki;Y. Kameda;Y. Umebayashi
通过高能全散射（HETS）实验研究了由咪唑鎓[h2Im+]、N-甲基咪唑鎓[C1hIm+]和N,N'-二甲基咪唑鎓[C1mIm+]组成的双（三氟甲磺酰）酰胺TFSA基质子和非质子离子液体的液体结构。根据这些离子液体的 r2{GX-ray(r) - 1} 形式的微分径向分布函数中 6 和 9 Å 左右的峰，建议了由 N-甲基基团取代质子引起的最近相邻的阳离子-阴离子取向变化。据推测，NH · · · O 氢键导致阳离子-阴离子取向变化。为了进一步了解 PIL 中的氢键，进行了 MD 模拟，并且与实验吻合良好。根据三种离子液体的空间分布函数（SDF），TFSA−的O原子优先选择阳离子中具有最大正部分原子电荷的咪唑鎓的NH氢，而F原子位于咪唑鎓环平面的正上方和正下方。此外，NH······O氢键键长短，键角呈线性，而C2H···O相互作用长且弯曲。基于结构方面并结合热力学观点讨论了 PIL 中的 NH · · · O 氢键。
Liquid structure of bis-(trifluoromethanesulfonyl)amide TFSA−based protic and aprotic ionic liquids composed of imidazolium [h2Im+],N-methylimidazolium [C1hIm+] andN,N’-dimethylimidazolium [C1mIm+] were investigated by high-energy total scattering (HETS) experiments. The nearest neighboring cation–anon orientation variations by theN-methyl groups substitution to proton were suggested based on the peaks at around 6 and 9 Å in the differential radial distribution functions as the form ofr2{GX-ray(r) - 1} for these ionic liquids. It was supposed that the NH · · · O hydrogen bond causes the cation–anion orientation variations. To obtain further insight into the hydrogen bond in the PIL, MD simulations performed and agreed well with the experiments. According to spatial distribution functions (SDF) for the three ionic liquids, the O atom of TFSA−prefers the NH hydrogen of the imidazolium that has the most positive partial atomic charge in the cation, while the F atom locates right above and right below the imidazolium ring plane. In addition, the NH · · · O hydrogen bond has short bond lengths and linear bond angles, while the C2H · ·O interaction is long and bent. The NH · · · O hydrogen bond in the PIL was discussed based on structural aspect accompanied by a thermodynamic viewpoint.