Molecular electrostatic force, solution electrostatic energy and solubility of polar and non-polar molecules in water

Abstract

This paper gives a simple expression for calculating the electrostatic energy of a system that consists of a solute molecule surrounded by its first layer solvent shell. From the gradient of this energy, the normal force exerted by the solvent may be found. These expressions assume that the electron density of the whole system can be written as a sum of spherical Gaussian functions. A correlation is given which indicates how the solubility in water of a set of molecules is related to the minimum total electrostatic energy between the first solvation shell and the solute molecule. This shows why the geometrical and electrical indices given in previous work correlate so well with solubility. Contours of the modulus of the molecular electrostatic force (MEF) are shown to give a good definition of the molecular surface for water.