Exponential Scaling of Water Exchange Rates with Ion Interaction Strength from the Perspective of Dynamic Facilitation Theory

TL;DR

This paper models water exchange rates around ions using dynamic facilitation theory, revealing an exponential relationship between exchange timescale and ion-water interaction strength.

Contribution

It introduces a coarse-grained lattice model applying dynamic facilitation theory to water exchange, highlighting the exponential scaling with interaction strength.

Findings

Water exchange timescale scales exponentially with ion-water interaction strength.

The model captures the sensitivity of exchange rates to ionic chemistry perturbations.

Dynamic facilitation theory provides a new perspective on aqueous ion exchange dynamics.

Abstract

Water exchange reactions around ionic solutes are ubiquitous in aqueous solution-phase chemistry. However, the extreme sensitivity of exchange rates to perturbations in the chemistry of an ionic solute is not well understood. We examine water exchange around model ions within the language of dynamic facilitation theory, typically used to describe glassy and other systems with collective, facilitated dynamics. Through the development of a coarse-grained, kinetically-constrained lattice model of water exchange, we show that the timescale for water exchange scales exponentially with the strength of the solute-solvent interactions.