In Situ Monitoring of Unique Switching Transitions in the Pressure-Amplifying Flexible Framework Material DUT-49 by High-Pressure 129Xe NMR Spectroscopy
Research output: Contribution to journal › Research article › Contributed › peer-review
Contributors
Abstract
The pronounced flexibility of special metal-organic frameworks (MOFs), so-called soft porous crystals, is attracting increasing research interest. Studies of host-guest interactions in such materials are especially powerful if the measurements are performed in situ. 129Xe NMR spectroscopy is favorable because it provides characteristic, structure-sensitive parameters such as chemical shifts. The combination of high-pressure xenon adsorption with 129Xe NMR spectroscopy was used to elucidate the adsorption-induced phase transitions in the recently discovered pressure-amplifying framework material DUT-49, showing a unique negative gas adsorption (NGA) transition. In the open-pore state, DUT-49op exhibits a hierarchical pore system involving both micro- and mesopores. After reaching a critical relative pressure of ca. 0.15, adsorbed xenon induces mesopore contraction, resulting in a purely microporous contracted-pore phase. This contraction is accompanied by release of xenon from the mesopores. Further increase of the pressure initiates the recovery of the mesopores without any indication of a structural intermediate in the NMR spectra. According to the NMR data, the structural transition induced by xenon is a collective, stepwise phenomenon rather than a continuous process. This is the first time that NGA has been studied by directly monitoring the guest and its interaction with the host framework. (Graph Presented).
Details
Original language | English |
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Pages (from-to) | 5195-5200 |
Number of pages | 6 |
Journal | Journal of Physical Chemistry C, Nanomaterials and interfaces |
Volume | 121 |
Issue number | 9 |
Publication status | Published - 9 Mar 2017 |
Peer-reviewed | Yes |