The attractive -T S DS -,W ⊕C (z) for interfacial DS - agrees with the analysis of van der Waals vs electrostatic free energy components on the basis of the Gibbs-Bogoliubov inequality presented in Ref. 55. The crux of the argument is as follows: electrostatic interactions-in this case: DS --water charge-dipole interactions-are strongly directional, while van der Waals interactions are largely non-directional. Therefore, we expect solvation in a polar solvent to lead to stronger structuring of the solvent around the solute corresponding to a broadening of the E DS -,W ⊕C (z) distribution, while there is comparatively little structuring of a nonpolar solvent around the solute. In the context of DS - adsorption to the ACWI, the difference between water, a polar solvent, and C 12 E 6 , a largely nonpolar medium, leads to the observed attractive -T S DS -,W ⊕C (z) profile. We will return to this idea when discussing DS 0 adsorption below.