Ab initio molecular dynamics simulations of SO2 solvation in choline chloride/glycerol deep eutectic solvent

Deep eutectic solvents (DESs) are mixtures of ionic compounds and molecular hydrogen bond donors. Due to the many components and their different interacting subgroups, they give rise to a plethora of many different interactions which can be studied by ab initio molecular dynamics simulations, because within this method all the forces are calculated on the fly and no parametrization prior to the calculation is necessary. Since DESs can be applied in gas capture, for example for SO2 absorption, we performed ab initio molecular dynamics studies of both the pure choline chloride/glycerol DES and the same mixed with SO2. We identified the hydrogen bonding and other specific interactions between all components. With addition of SO2, we observed a decrease in the anion-OH group interplay, because the chloride anions form complexes with the SO2 molecules. Furthermore, the SO2 molecules are incorporated into the hydrophobic network and the interaction between the hydrogen bonds of all OH groups remain constant. This decrease of anion-OH interaction might be responsible for the more fluid state of the SO2-DESs mixture than the pure DES.