Dielectric spectroscopy of water dynamics in functionalized UiO-66 metal-organic frameworks
Journal
Molecules
Journal Volume
25
Journal Issue
8
Pages
1962
Date Issued
2020
Author(s)
Balčiūnas, Sergejus
Pavlovaite D
Kinka M
Yeh J.-Y
Han P.-C
Shieh F.-K
Wu K.C.-W
Šimenas, Mantas
Grigalaitis R
Banys J.
Abstract
We present a dielectric spectroscopy study of dipolar dynamics in the hydrated UiO-66(Zr) type metal-organic frameworks (MOFs) functionalized with ?NH2 and ?F groups. Experiments are performed in a broad temperature and frequency ranges allowing us to probe several dipolar relaxations. For both samples at temperature below 220 K, we observe confined supercooled water dynamics, which can be described by the Arrhenius law. At slightly higher temperature, a second less pronounced dipolar relaxation is identified, and its origin is discussed. At even higher temperature, the dielectric permittivity exhibits anomalous increase with increasing temperature due to the proton conductivity. Upon further heating, the permittivity shows a sudden decrease indicating a reversible removal of water molecules. Measurements of the dehydrated samples reveal absence of all three dipolar processes. ? 2020 by the authors.
Subjects
metal organic framework; organometallic compound; phthalic acid derivative; UiO-66; water; algorithm; chemical model; chemical structure; chemistry; impedance spectroscopy; temperature; Algorithms; Dielectric Spectroscopy; Metal-Organic Frameworks; Models, Chemical; Molecular Structure; Organometallic Compounds; Phthalic Acids; Temperature; Water
Type
journal article