Chowdhury Tubai, Chatterjee Srijan, Deshmukh Samadhan H, Bagchi Sayan
Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
J Phys Chem B. 2023 Aug 24;127(33):7299-7308. doi: 10.1021/acs.jpcb.3c02191. Epub 2023 Aug 10.
Deep eutectic solvents, promising green alternatives to conventional solvents, consist of a hydrogen bond donor and a hydrogen bond acceptor. The hydrogen bonding components in deep eutectic solvents form an extended hydrogen bonding network, which can be tuned to specific applications by changing the hydrogen bond donors. In this work, we have changed the hydrogen bond donor from a diol to a dicarboxylic acid by systematically replacing a hydroxyl group with an acid group one at a time to investigate the solvation structure and dynamics of the deep eutectic systems. Using a combination of ultrafast vibrational spectroscopy and molecular dynamics simulations, we compared the spectral diffusion and orientational relaxation dynamics of three deep eutectic systems using the vibrational responses of a dissolved anion. Our results indicate that although the solvation structures are marginally different across the systems, distinct differences are present in the solvent fluctuation and solute reorientation dynamics. This work provides a detailed molecular understanding of carboxylic-acid-based deep eutectic systems and how they differ from alcohol-based deep eutectic systems.
深共熔溶剂是传统溶剂颇具前景的绿色替代品，由氢键供体和氢键受体组成。深共熔溶剂中的氢键组分形成了一个扩展的氢键网络，通过改变氢键供体可将其调整以适用于特定应用。在这项工作中，我们通过每次用一个酸基团系统地取代一个羟基，将氢键供体从二醇改变为二羧酸，以研究深共熔体系的溶剂化结构和动力学。结合超快振动光谱和分子动力学模拟，我们利用溶解阴离子的振动响应比较了三种深共熔体系的光谱扩散和取向弛豫动力学。我们的结果表明，尽管各体系间的溶剂化结构略有不同，但在溶剂波动和溶质重取向动力学方面存在明显差异。这项工作提供了对基于羧酸的深共熔体系及其与基于醇的深共熔体系差异的详细分子理解。
