Issue 2, 2017

The opposite effects of sodium and potassium cations on water dynamics

Abstract

Water rotational dynamics in NaSCN and KSCN solutions at a series of concentrations are investigated using femtosecond infrared spectroscopy and theory. Femtosecond infrared measurements, consistent with previous NMR observations, detect that sodium slows down while potassium accelerates the water O–H bond rotation. Results of reported neutron scattering measurements, on the other hand, suggested that these two cations have similar structure-breaking effects on water, and therefore should both accelerate water rotation through the presumably dominating large-amplitude angular jump component. To explain this discrepancy, theoretical studies with both classical and ab initio models were carried out, which indicate that both ions indeed accelerate the large-amplitude angular jump rotation of the water molecules, while the observed cation specific effect originates from the non-negligible opposite impact of the sodium and potassium cations on the diffusive rotation of water molecules.

Graphical abstract: The opposite effects of sodium and potassium cations on water dynamics

Supplementary files

Article information

Article type
Edge Article
Submitted
26 jul 2016
Accepted
13 okt 2016
First published
14 okt 2016
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2017,8, 1429-1435

The opposite effects of sodium and potassium cations on water dynamics

Q. Zhang, H. Chen, T. Wu, T. Jin, Z. Pan, J. Zheng, Y. Gao and W. Zhuang, Chem. Sci., 2017, 8, 1429 DOI: 10.1039/C6SC03320B

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