Unusual Proton Transfer Kinetics in Water at the Temperature of Maximum Density

Emilia V. Silletta, Mark E. Tuckerman, and Alexej Jerschow

Phys. Rev. Lett. 121, 076001 – Published 13 August 2018

Abstract

Water exhibits numerous anomalous properties, many of which remain poorly understood. One of its intriguing behaviors is that it exhibits a temperature of maximum density (TMD) at $4 ° C$ . We provide here new experimental evidence for hitherto unknown abrupt changes in proton transfer kinetics at the TMD. In particular, we show that the lifetime of ${OH}^{-}$ ions has a maximum at this temperature, in contrast to hydronium ions. Furthermore, base-catalyzed proton transfer shows a sharp local minimum at this temperature, and activation energies change abruptly as well. The measured lifetimes agree with earlier theoretical predictions as the temperature approaches the TMD. Similar results are also found for heavy water at its own TMD. These findings point to a high propensity of forming fourfold coordinated ${OH}^{-}$ solvation complexes at the TMD, underlining the asymmetry between hydroxide and hydronium transport. These results could help to further elucidate the unusual properties of water and related liquids.

Received 30 April 2018
Revised 26 June 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.076001

Physics Subject Headings (PhySH)

Water

Molecular dynamics Nuclear magnetic resonance

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Emilia V. Silletta¹, Mark E. Tuckerman^1,2,3, and Alexej Jerschow^1,*

¹Department of Chemistry, New York University, New York, New York 10003, USA
²Courant Institute of Mathematical Science, New York University, New York, New York 10012, USA
³NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshan Road North, Shanghai 200062, China