Role of Nonlocal Electrostatic Effects in the Stabilization of Monovalent Cations in an Aqueous Cavity Surrounded by a Weakly Polar Environment

Earlier, we developed (Russ. J. Electrochem., 2018, vol. 54, p. 879) a new nonlocal electrostatic method for calculating an electric field distributions in systems containing spatially constrained regions filled with polar media with nonlocal dielectric properties. This method is used for nonlocal electrostatic analysis of the stabilization of a monovalent cation in a spherical cavity filled with water and surrounded by a local dielectric. For one- and three-mode models of the dielectric function, nonlocal electrostatic formulas are obtained for the field distribution inside such a cavity, if the ion is located at its center. The nonlocal electrostatic relations are derived for the change in the cation solvation energy ΔW during its transfer from solution to the center of such a cavity. It is shown that when the correlation length of water in the cavity decreased as compared with the solution (at the same values of the dielectric constant of water in the cavity and in the solution bulk), the amount of work required for the ion transfer from the solution into the cavity (−ΔW) decreased significantly as compared to that calculated by using the local theory used in the work of Roux, B. and MacKinnon, R. (Science, 1999, vol. 285, p. 100).