Solvent Effects in Chloroform Solution: Parametrization of the MST/SCRF Continuum Model

Abstract

The suitability of the self-consistent reaction field (SCRF) strategy for the study of solutes in chloroform solution has been examined. The SCRF method developed by Miertus, Scrocco and Tomasi (MST) has been parametrized at both ab initio 6-31G* and semiempirical AM1, MNDO, and PM3 levels. The reliability of the MST/SCRF model has been assessed from the comparison with results derived from classical Monte Carlo−free energy perturbation simulations and from mixed Monte Carlo−quantum mechanical/molecular mechanical computations, as well as with experimental data. The parametrized MST/SCRF method estimates the free energy of solvation with a root-mean-square deviation of 0.4 kcal/mol from the experimental value for the molecules studied. Further confidence in the optimized method stems from its ability to reproduce the tautomeric change of 2- and 4-pyridone upon transfer from gas phase to chloroform and the partition coefficient for compounds not considered in the parametrization. The results indicate the suitability of the MST/SCRF model for the study of solvent effects in dilute chloroform solutions.