Chatterjee Srijan, Chowdhury Tubai, Bagchi Sayan
Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
J Chem Phys. 2023 Mar 21;158(11):114203. doi: 10.1063/5.0139153.
Deep eutectic solvent is a mixture of two or more components, mixed in a certain molar ratio, such that the mixture melts at a temperature lower than individual substances. In this work, we have used a combination of ultrafast vibrational spectroscopy and molecular dynamics simulations to investigate the microscopic structure and dynamics of a deep eutectic solvent (1:2 choline chloride: ethylene glycol) at and around the eutectic composition. In particular, we have compared the spectral diffusion and orientational relaxation dynamics of these systems with varying compositions. Our results show that although the time-averaged solvent structures around a dissolved solute are comparable across compositions, both the solvent fluctuations and solute reorientation dynamics show distinct differences. We show that these subtle changes in solute and solvent dynamics with changing compositions arise from the variations in the fluctuations of the different intercomponent hydrogen bonds.
深共熔溶剂是两种或更多种组分的混合物，按一定摩尔比混合，使得该混合物在低于各单一物质的温度下熔化。在这项工作中，我们结合了超快振动光谱和分子动力学模拟，来研究深共熔溶剂（1:2氯化胆碱：乙二醇）在共熔组成处及附近的微观结构和动力学。特别地，我们比较了这些不同组成体系的光谱扩散和取向弛豫动力学。我们的结果表明，尽管溶解溶质周围的时间平均溶剂结构在不同组成之间具有可比性，但溶剂涨落和溶质重取向动力学都显示出明显差异。我们表明，溶质和溶剂动力学随组成变化的这些细微变化源于不同组分间氢键涨落的变化。
