Abstract: The kinetics of water diffusion in metal-organic frameworks is critical for applications such as atmospheric water harvesting, yet its real‑time molecular‑level monitoring remains challenging. Herein, we propose an in situ electron paramagnetic resonance approach based on an encapsulated spin probe to investigate water diffusion into MOF UiO‑66. The EPR spectral lineshape is highly sensitive to the local mobility of the radical. As water molecules get adsorbed within the pores over the course of the measurement, the spectral lines gradually narrow. EPR measurements reveal that water uptake in TEMPO@UiO-66 is a slow process, taking place over more than 50 h. Molecular dynamics simulations corroborate these experimental findings, showing changes in radical motion with distinct trends during water adsorption. This approach enables real‑time monitoring of water diffusion, offering a versatile tool for studying host–guest dynamics in porous materials and guiding the development of advanced sorbents.

Cite: Albrekht Y.N. , Alimov D.V. , Larionov K.P. , Aidakova K.A. , Poryvaev A.S. , Fedin M.V.
In Situ Investigation of Water Diffusion into UiO-66 Using EPR of Encapsulated Spin Probe
Journal of Structural Chemistry (Журнал структурной химии). 2026. V.67. N8. P.1682-1693. DOI: 10.1134/s0022476626080032 WOS Scopus OpenAlex

Dates:

Submitted:	Apr 3, 2026
Accepted:	Apr 28, 2026
Published print:	Sep 4, 2026

Identifiers:

≡ Web of science:	WOS:001868313500014
≡ Scopus:	2-s2.0-105049417336
≡ OpenAlex:	W7208787305

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