Dances With Hydrogen Cations

摘要

Life depends on the flow of hydrogen cations in water, yet their dynamic behaviour when in complex with water molecules is unknown. The latest computer simulations cast light on the jiggling of these hydrated ions. In water, hydrogen cations (H~+) abound, but they exist only as complexes with water molecules. One of the most important of these complexes is the Zundel cation, in which a hydrogen cation is shared by two water molecules. The structure of the Zundel cation has been known for years, owing to evidence from infrared (IR) spectra. But its dynamic behaviour - how the hydrogen cation moves between the two water molecules - is unknown. In Angewandte Chemie, Vendrell et al. report accurate computer simulations of the IR spectrum of the Zundel ion in the gas phase, and of analogues in which hydrogen atoms have been replaced with deuterium atoms. This allows the first complete characterization of the complex molecular vibrations of Zundel ions, providing information that might contribute to a long-sought-after goal - an accurate computational model of how hydrogen ions are transported through liquid water.