Nuclear Magnetic Relaxation Studies of Preferential Solvation in Electrolyte Solutions

Abstract

Formulae are derived which describe the increase in the total proton magnetic relaxation rate relative to the intramolecular relaxation rate in a solvent mixture when solvent molecules of one kind are enriched in the solvation sphere of a dissolved ion. Experimental nuclear magnetic relaxation results regarding the application of these formulae for solutions of Mg(ClO4)2, KI and RbI in water + methanol mixtures are reported. It is shown that preferential solvation effects are present in these systems, they are ascribed to preferential hydration of the cations.