Noh, Y.
, Riccardi, D.
and Smolyanitsky, A.
(2025),
Entropic modulation of divalent cation transport, Physical Review Letters, [online], https://doi.org/10.1103/vtw2-z4f8, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959826
(Accessed November 25, 2025)
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Entropic modulation of divalent cation transport
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Abstract
Aqueous cations permeate subnanoscale pores by crossing free energy barriers dominated by competing enthalpic contributions from transiently decreased ion-solvent and increased ion-pore electrostatic interactions. This commonly accepted view is rooted in the studies of monovalent cation transport. Divalent cations, however, have significantly higher desolvation costs, requiring considerably larger pores to enable retention of the first hydration shell and subsequently transport. We show that this scenario gives rise to a strong enthalpy-entropy competition. Specifically, the first hydration shell is shown to undergo rotational ordering inside the pore, resulting in a tight transition state. Our results shed light on the basic mechanisms of transport barrier formation for aqueous divalent cations permeating nanoporous 2D membranes.Citation
Physical Review Letters
Volume
135
Issue
13
Pub Type
Journals
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Keywords
ion transport, thermodynamics, entropy, enthalpy, theory, molecular dynamics
Citation
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Created September 22, 2025, Updated September 27, 2025