Issue 33, 2021

Dynamic ionic radius of alkali metal ions in aqueous solution: a pulsed-field gradient NMR study

Abstract

The dynamic behavior of alkali metal ions, Li+, Na+, K+, Rb+ and Cs+ in aqueous solutions is one of the most important topics in solution chemistry. Since these alkali metals contain nuclear magnetic resonance (NMR) active nuclei, it is possible to directly measure the diffusion constants of the alkali metal ions using the pulsed field gradient (PFG) NMR method. In this paper, the 7Li, 23Na, 87Rb, 133Cs and 1H resonances are observed for diffusion constants in aqueous solution and the solvent H2O. Until now, the values of the diffusion constant have been lacking when discussing hydration effects around alkali metal ions. It is known that the static ionic radius (Rion) increases with increasing the atomic number, and the experimental diffusion constants also increase with increasing the atomic number, which is opposite to the Stokes–Einstein (SE) relation. It suggests that alkali metal ions diffuse through a space of 10−6 m accompanying the hydrated spheres with a time interval of 10−3 s. For each alkali metal ion, the dynamic ionic radius is evaluated.

Graphical abstract: Dynamic ionic radius of alkali metal ions in aqueous solution: a pulsed-field gradient NMR study

Supplementary files

Article information

Article type
Paper
Submitted
23 Mar 2021
Accepted
19 May 2021
First published
07 Jun 2021
This article is Open Access
Creative Commons BY license

RSC Adv., 2021,11, 20252-20257

Dynamic ionic radius of alkali metal ions in aqueous solution: a pulsed-field gradient NMR study

K. Hayamizu, Y. Chiba and T. Haishi, RSC Adv., 2021, 11, 20252 DOI: 10.1039/D1RA02301B

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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