Reorientional dynamics of water molecules in anionic hydration shells.
Water molecule rotational dynamics within a chloride anion's first hydration shell are investigated through simulations. In contrast to recent suggestions that the ion's hydration shell is rigid during a water's reorientation, we find a labile hydration sphere, consistent with previous assessments of chloride as a weak structure breaker. The nondiffusive reorientation mechanism found involves a hydrogen-bond partner switch with a large amplitude angular jump and the water's departure from the anion's shell. An analytic extended jump model accounts for the simulation results, as well as available NMR and ultrafast spectroscopic data, and resolves the discrepancy between them.
Laage
Damien
D
Département de Chimie, Unité Mixte de Recherche 8640 PASTEUR, Ecole Normale Supérieure, 24 Rue Lhomond, 75231 Paris Cedex 05, France. damien.laage@ens.fr
Hynes
James T
JT