A Novel Technique To Predict the Solubility of Planar Molecules

Abstract

We present a new computational technique to quantify the solubility of planar molecules in a solvent. Solubility is calculated as the critical concentration at which solute molecules cease to stack as columns, but rather aggregate in all directions. An explicit expression for the solubility is obtained, which involves the potential of mean force between two solute molecules as a function of their center-of-mass distance in the limit of infinite dilution. This function can be easily obtained from molecular dynamics simulations involving a pair of solute molecules in a solvent using the umbrella-sampling method. As a validation of our approach, we use a generic coarse-grained molecular model to represent the molecular interactions of polycyclic-aromatic-hydrocarbon. Within that coarse-grained model, the solubility of pyrene and acenaphthene in heptane is estimated through large molecular dynamics simulations and compared to the experimental results. The umbrella-sampling method, applied to single pairs of t...