Department of Chemistry, University of Basel, CH-4056 Basel, Switzerland.
Department of Chemistry, University of Zurich, CH-8057 Zürich, Switzerland.
J Am Chem Soc. 2022 Aug 10;144(31):14170-14180. doi: 10.1021/jacs.2c04169. Epub 2022 Jul 27.
The spectroscopy and structural dynamics of a deep eutectic mixture (KSCN/acetamide) with varying water content is investigated from 2D IR (with the C-N stretch vibration of the SCN anions as the reporter) and THz spectroscopy. Molecular dynamics simulations correctly describe the nontrivial dependence of both spectroscopic signatures depending on water content. For the 2D IR spectra, the MD simulations relate the steep increase in the cross-relaxation rate at high water content to the parallel alignment of packed SCN anions. Conversely, the nonlinear increase of the THz absorption with increasing water content is mainly attributed to the formation of larger water clusters. The results demonstrate that a combination of structure-sensitive spectroscopies and molecular dynamics simulations provides molecular-level insights into the emergence of heterogeneity of such mixtures by modulating their composition.
研究了具有不同含水量的深共晶混合物（KSCN/乙酰胺）的光谱和结构动力学，从二维红外（以 SCN 阴离子的 C-N 伸缩振动作为报道者）和太赫兹光谱进行研究。分子动力学模拟正确描述了这两种光谱特征随含水量的变化的复杂依赖性。对于二维红外光谱，MD 模拟将高含水量下交叉弛豫速率的急剧增加与堆积 SCN 阴离子的平行排列相关联。相反，随着含水量的增加，太赫兹吸收的非线性增加主要归因于较大的水分子簇的形成。结果表明，通过调节混合物的组成，将结构敏感的光谱学和分子动力学模拟相结合，可以提供对这种混合物异质性出现的分子水平的见解。
