Fetisov Evgenii O, Harwood David B, Kuo I-Feng William, Warrag Samah E E, Kroon Maaike C, Peters Cor J, Siepmann J Ilja
Department of Chemistry and Chemical Theory Center, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States.
Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory , Livermore, California 94550, United States.
J Phys Chem B. 2018 Jan 25;122(3):1245-1254. doi: 10.1021/acs.jpcb.7b10422. Epub 2018 Jan 5.
First-principles molecular dynamics simulations in the canonical ensemble at temperatures of 333 and 363 K and at the corresponding experimental densities are carried out to investigate the behavior of the 1:2 choline chloride/urea (reline) deep eutectic solvent and its equimolar mixture with water. Analysis of atom-atom radial and spatial distribution functions and of the H-bond network reveals the microheterogeneous structure of these complex liquid mixtures. In neat reline, the structure is governed by strong H-bonds of the trans- and cis-H atoms of urea to the chloride ion. In hydrous reline, water competes for the anions, and the H atoms of urea have similar propensities to bond to the chloride ions and the O atoms of urea and water. The vibrational spectra exhibit relatively broad peaks reflecting the heterogeneity of the environment. Although the 100 ps trajectories allow only for a qualitative assessment of transport properties, the simulations indicate that water is more mobile than the other species and its addition also fosters faster motion of urea.
在333 K和363 K温度下的正则系综中，以及在相应的实验密度下，进行了第一性原理分子动力学模拟，以研究1:2氯化胆碱/尿素（低共熔溶剂）及其与水的等摩尔混合物的行为。对原子-原子径向和空间分布函数以及氢键网络的分析揭示了这些复杂液体混合物的微观非均相结构。在纯低共熔溶剂中，结构由尿素的反式和顺式H原子与氯离子之间的强氢键控制。在含水低共熔溶剂中，水与阴离子竞争，尿素的H原子与氯离子以及尿素和水的O原子形成键的倾向相似。振动光谱显示出相对较宽的峰，反映了环境的非均质性。尽管100 ps的轨迹仅允许对传输性质进行定性评估，但模拟表明水比其他物种更具流动性，并且水的加入也促进了尿素更快的运动。
