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Slowing Down of the Molecular Reorientation of Water in Concentrated Alkaline Solutions.

ABSTRACT: It is generally accepted that the hydroxide ion (OH-) is a strong hydrogen bond acceptor and that its anomalously high diffusion constant in water results from a Grotthuss-like structural diffusion mechanism. However, the spatial extent over which OH- ions influence the dynamics of the hydrogen-bond network of water remained largely unclear. Here, we measure the ultrafast dynamics of OH groups of HDO molecules interacting with the deuterated hydroxide ion OD-. For solutions with OD- concentrations up to 4 M, we find that HDO molecules that are not directly interacting with the ions have a reorientation time constant of ?2.7 ps, similar to that of pure liquid water. When the concentration of OD- ions is increased, the reorientation time constant increases, indicating a strong slowing down of the structural dynamics of the solution.

SUBMITTER: Cota R

PROVIDER: S-EPMC7520889 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Slowing Down of the Molecular Reorientation of Water in Concentrated Alkaline Solutions.

Cota Roberto R van Dam Eliane P EP Woutersen Sander S Bakker Huib J HJ

The journal of physical chemistry. B 20200909 38

It is generally accepted that the hydroxide ion (OH-) is a strong hydrogen bond acceptor and that its anomalously high diffusion constant in water results from a Grotthuss-like structural diffusion mechanism. However, the spatial extent over which OH- ions influence the dynamics of the hydrogen-bond network of water remained largely unclear. Here, we measure the ultrafast dynamics of OH groups of HDO molecules interacting with the deuterated hydroxide ion OD-. Fo ...[more]

PMID: 32841025

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