Liquid structure of the choline chloride-urea deep eutectic solvent (reline) from neutron diffraction and atomistic modelling
Liquid structure of the choline chloride-urea deep eutectic solvent (reline) from neutron diffraction and atomistic modelling
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DOI：
10.1039/c5gc02914g
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发表时间：
2016-01-01
期刊：
影响因子：
9.8
通讯作者：
Edler, Karen J.
中科院分区：
文献类型：
--
作者：
Hammond, Oliver S.;Bowron, Daniel T.;Edler, Karen J.
在303 K下测定了典型的深共晶溶剂（DES）线的液体结构，即氯化胆碱和尿素的1:1摩尔混合物。本文采用H/D同位素取代法获得了液相中子衍射实验数据，并对实验数据进行了经验势结构精化（EPSR）模型拟合。从EPSR得到的径向分布函数（RDFs）揭示了液体中存在预期的氢键网络，不仅尿素和氯化物之间，而且所有DES组分之间都存在显著的有序相互作用。空间密度函数（sdf）用于绘制溶剂的三维结构。有趣的是，人们发现胆碱通过羟基对这种键合网络有很大的贡献，从而在所有物种之间形成了一个有秩序的径向分层结构。计算的孔隙尺寸分布函数表明，DESs内存在的孔洞比以前孔洞理论所认为的要小得多。这些观察结果对这些“设计溶剂”的未来发展具有重要意义。
The liquid structure of the archetypal Deep Eutectic Solvent (DES) reline, a 1 : 2 molar mixture of choline chloride and urea, has been determined at 303 K. This is the first reported liquid-phase neutron diffraction experiment on a cholinium DES. H/D isotopic substitution is used to obtain differential neutron scattering cross sections, and an Empirical Potential Structure Refinement (EPSR) model is fitted to the experimental data. Radial distribution functions (RDFs) derived from EPSR reveal the presence of the anticipated hydrogen bonding network within the liquid, with significant ordering interactions not only between urea and chloride, but between all DES components. Spatial density functions (SDFs) are used to map the 3D structure of the solvent. Interestingly, choline is found to contribute strongly to this bonding network via the hydroxyl group, giving rise to a radially layered structure with ordering between all species. The void size distribution function calculated for reline suggests that the holes present within DESs are far smaller than previously suggested by hole theory. These observations have important implications in the future development of these 'designer solvents'.