Comparison of Structural Stability of Deep Eutectic Solvents Based on Choline chloride/Fatty acids and Thymol/Fatty acids in Aqueous Solutions: Insights from Molecular Dynamics Simulation Studies

Abstract

Abstract In this work, intermolecular interactions among the species of fatty acids-based DESs and based DESs with fatty acids as hydrogen bond donors (HBD) in the adjacent water have been investigated using molecular dynamics (MD) simulation. The results of this work provide deep insights to understand the water stability of thymol-based DESs and the eutectic mixtures of choline chloride and fatty acids at a temperature of 353.15 K and atmospheric pressure. The strength of the hydrogen bond as well as the distribution of the HBA and HBD around each other was attributed to the alkyl chain length of FAs and the type of HBD. Assessed structural properties include the combined distribution functions (CDFs), the radial distribution functions (RDFs), the angular distribution functions (ADFs), and the Hydrogen bonding network between species and Spatial distribution functions (SDF). The reported results show the remarkable role of the strength of the hydrogen bond between THY molecules and fatty acids on the stability of DES in water. The transport properties of molecules in the binary mixtures in the water was analyzed by using the mean square displacement (MSD) of the centers of mass of the species, self-diffusion coefficients, vector reorientation dynamics (VRD) of bonds and the velocity autocorrelation function (VACF) for the center of the mass of species.