Solvation Free Energies For Aqueous And Nonaqueous Solutions Computed Using Pm7 Atomic Charges

We describe a simple and accurate method, ESE-PM7, for calculating solvation free energies Delta G(solv)degrees in aqueous and nonaqueous solutions. The method is based on a noniterative COSMO algorithm. Molecular geometries and atomic charges calculated using the semiempirical method PM7 are used to calculate Delta G(solv)degrees. The method has been tested on 92 different solvents and 988 solutes. The mean absolute errors (MAEs) in Delta G(solv)degrees in aqueous solutions estimated by the ESE-PM7 approach are found to be 1.62 kcal/mol for 389 neutral solutes and 3.06 kcal/mol for 139 ions. The MAEs for neutral molecules in organic solvents are 0.97, 0.74, and 0.51 kcal/mol in polar protic, polar aprotic, and nonpolar solvents, respectively. The developed method can be employed to quickly screen Delta G(solv)degrees values of extended molecular systems including pharmaceutical and biological molecules.