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

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...

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Detalles Bibliográficos
Autores principales: Hayamizu, Kikuko, Chiba, Yusuke, Haishi, Tomoyuki
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society of Chemistry 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9033755/
https://www.ncbi.nlm.nih.gov/pubmed/35479919
http://dx.doi.org/10.1039/d1ra02301b
Descripción
Sumario: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 (7)Li, (23)Na, (87)Rb, (133)Cs and (1)H resonances are observed for diffusion constants in aqueous solution and the solvent H(2)O. 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 (R(ion)) 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.