Resolving solvophobic interactions inferred from experimental solvation free energies and evaluated from molecular simulations

Abstract

Ben-Naim estimated the solvent-mediated interaction between methanes based on experimental solvation free energy differences between chemically similar hydrocarbons. Interactions were predicted to be strongest in water, dominated by characteristic entropic gains. We use molecular simulations in combination with an empirical interpolation procedure that bridges interactions from outside methane’s excluded volume down to overlap to test Ben-Naim’s estimates. While Ben-Naim’s approach captures many distinctive trends, the alchemical differences between methane and a methyl unit play a non-trivial role on the predicted association strength and the sign of enthalpic and entropic components of the interaction free energy in water and ethanol.