Molecular Dynamic Insights into the Distinct Solvation Structures of Aromatic and Aliphatic Compounds in Monoethanolamine-Based Deep Eutectic Solvents

On the Solvation Properties of Menthol-Thymol Mixtures. A Molecular Dynamics Investigation

Using classical molecular dynamics, we have investigated the solvation of catechol, resorcinol, hydroquinone and 1,4-benzoquinone at infinite dilution, in a series of menthol - thymol mixtures in which the molar fraction of thymol (xTHY) has been increased by steps of 0.1, from 0 (pure menthol) to 1 (pure thymol). The evolution of the solvation shell around the solutes reveals that when xTHY is increased, the average number of hydrogen bonds (HB) where the solute acts as HB acceptor (HBA) and the solvent as HB donor (HBD) increases, while the amount of HB, in which the solute acts as HBD and the solvent as HBA, decreases. Overall, the total number of HBs between the different benzenediols and the solvent decreases with an increase of xTHY, while for benzoquinone the total number of HB increases. This points to the fact that "acidic" or HBD molecules are better solvated in mixtures with high menthol proportion, while "basic" or HBA molecules, are better solvated in thymol rich mixtures. The results reported herein follow the same trends as experimentally reported Kamlet-Taft parameters and present insights on how the composition of these "deep eutectic" mixtures maybe tweaked in order to optimize their solvation properties.

A comparative study of deep eutectic solvents based on fatty acids and the effect of water on their intermolecular interactions

In this work, intermolecular interactions among the species of fatty acids-based DESs with different hydrogen bond acceptors (HBA) in the adjacent water have been investigated using molecular dynamics (MD) simulation. The results of this work provide deep insights into understanding the water stability of the DESs based on thymol and the eutectic mixtures of choline chloride and fatty acids at a temperature of 353.15 K and atmospheric pressure. Stability, hydrogen bond occupancy analysis, and the distribution of the HBA and HBD around each other were attributed to the alkyl chain length of FAs and the type of HBA. 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 water-eutectic mixtures were 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.