Solvent effect on selectivity of between Na+ and Li+ ion to 18-crown-6: Monte Carlo simulation study

Abstract

The solvent effects on the relative free energies of binding of Na+ and Li+ ion to 18-crown-6, i.e., selectivity and ΔlogKs (the difference of stability constant of binding) have been investigated by a Monte Carlo simulation of statistical perturbation theory (SPT) in diverse solvents. Comparing the relative free energies of binding of Na+ and Li+ ion to 18-crown-6 and ΔlogKs of Na+ and Li+ ion to 18-crown-6, in CH3OH of this study with the experimental, there is a good agreement between the studies. We have noted that Born’s function of the solvents, the electron pair donor properties of the solvent and the differences in solvation dominate the differences in the stability constant (ΔlogKs) of Na+ and Li+ ion to 18-crown-6 and as well as the relative free energies of binding of Na+ and Li+ ion to 18-crown-6, i.e., selectivity of Na+ and Li+ ion to 18-crown-6. The results of this study appear promising for providing the selectivity and association properties of crown ethers with lanthanide trivalent ions among polar solvents and the less polar or non-polar solvents.