Monte Carlo simulations study for solvent effect on Cs+ to Rb+ ion mutation

The solvent effects on the relative free energies of solvation and the difference in partition coefficients (log P) for Cs+ to Rb+ mutation in several solvents have been investigated using Monte Carlo simulations with statistical perturbation theory. Comparing the relative free energies for interconversion of one ion pair, Cs+ to Rb+, in H2O (TIP4P) from this study with those published, that of this study is −7.52 kcal/mol, that of the published work is −7.8±1.6 kcal/mol and that of the experimental work is −7.7 kcal/mol. There is good agreement among the three studies if considering both methods used to obtain the hydration free energies and standard deviations. There is also good agreement between the calculated structural properties of this study and the published results. For those ion pairs, the solvent permittivity and the differences in solvation dominate the differences in the relative free energies of solvation and partition coefficients.