A quick solvation energy estimator based on electronegativity equalization.

Abstract

ESE-EE (Easy Solvation Estimation with Electronegativity equalization) is a quick method for estimation of solvation-free energies ΔGºsolv , which uses a thoroughly fitted electronegativity equalization (EE) scheme to obtain atomic charges, which are further employed in a scaled noniterative COSMO-like calculation to evaluate the electrostatic component of ΔGºsolv . Nonelectrostatic corrections including adjustable parameters are also added. For neutral solutes, ESE-EE yields a mean absolute error (MAE) in ΔGsolv ° of 1.5kcal/mol for aqueous solutions; 1.0kcal/mol for nonaqueous polar protic solvents; 0.9kcal/mol for polar aprotic solvents; and about 0.6kcal/mol for nonpolar solvents. Since ESE-EE only requires a molecular geometry as input for a ΔGºsolv prediction, it can be utilized for a rapid screening of ΔGºsolv for large neutral molecules. However, for ionic solutes, ESE-EE yields larger errors (typically several kcal/mol) and is recommendable for preliminary estimations only. Upon a special refitting, ESE-EE is able to yield partition coefficients with a good accuracy.