Theoretical study of the water/1,2-dichloroethane interface: Structure, dynamics, and conformational equilibria at the liquid–liquid interface

Abstract

Very little is known about the structure and dynamics of the interface between liquid water and liquid 1,2-dichloroethane (DCE), despite the fact that a molecular level understanding of this and similar interfaces is of fundamental importance for the proper interpretation of many studies of charge transfer at interfaces. Molecular dynamics calculations are used to show that the interface is molecularly sharp with capillary wavelike distortions whose structure and dynamics closely resemble those expected from the capillary wave model. Molecular level structural information such as pair correlation functions and hydrogen bonding statistics is also consistent with this picture. The orientation of water at the interface is similar to what is known at other water interfaces. The dynamics of water and DCE translational and rotational motion are only slightly modified at the interface. The DCE gauche–trans isomerization reaction is investigated at the interface and in the bulk. A continuum electrostatic model for the torsional potential of mean force is developed. Although this model can qualitatively account for the different conformational population in the bulk and at the interface, the difference is significantly overestimated.