Zahn Stefan
Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstraße 2, 04103 Leipzig, Germany.
Phys Chem Chem Phys. 2017 Feb 1;19(5):4041-4047. doi: 10.1039/c6cp08017k.
Deep eutectic solvents, mixtures of an organic compound and a salt with a deep eutectic melting point, are promising cheap and eco-friendly alternatives to ionic liquids. Ab initio molecular dynamics simulations of reline, a mixture consisting of urea and choline chloride, reveal that not solely hydrogen bonds allow similar interactions between both constituents. The chloride anion and the oxygen atom of urea also show a similar spatial distribution close to the cationic core of choline due to a similar charge located on both atoms. As a result of multiple similar interactions, clusters migrating together cannot be observed in reline which supports the hypothesis similia similibus solvuntur. In contrast to previous suggestions, the interaction of the hydroxyl group of choline with a hydrogen bond acceptor is overall rigid. Fast hydrogen bond acceptor dynamics is facilitated by the hydrogen atoms in the trans position to the carbonyl group of urea which contributes to the low melting point of reline.
深共熔溶剂是一种有机化合物和具有深共熔熔点的盐的混合物，是有望替代离子液体的廉价且环保的选择。对由尿素和氯化胆碱组成的混合物——reline进行的从头算分子动力学模拟表明，并非只有氢键能使两种成分之间产生类似的相互作用。氯离子阴离子和尿素的氧原子由于两者原子上的电荷相似，在靠近胆碱阳离子核心的位置也呈现出相似的空间分布。由于存在多种类似的相互作用，在reline中无法观察到一起迁移的簇，这支持了“相似者相溶”的假说。与之前的观点相反，胆碱的羟基与氢键受体的相互作用总体上是刚性的。尿素羰基反位的氢原子促进了氢键受体的快速动力学，这有助于reline的低熔点。
