High resolution solid state NMR in paramagnetic metal-organic frameworks
C A Klug1, M W Swift2, J B Miller1
1Chemistry Division, U.S. Naval Research Laboratory, Washington, DC, USA.
Solid State Nuclear Magnetic Resonance
|July 6, 2022
Summary
Nuclear magnetic resonance (NMR) spectroscopy reveals detailed insights into the metal-organic framework ZIF-67. This study demonstrates NMR
Area of Science:
- Materials Science
- Solid-State Chemistry
- Spectroscopy
Background:
- Metal-organic frameworks (MOFs) like ZIF-67 are porous materials with diverse applications.
- Understanding guest molecule interactions within MOFs is crucial for optimizing their performance.
Purpose of the Study:
- To investigate the utility of nuclear magnetic resonance (NMR) spectroscopy for characterizing ZIF-67 and guest molecules.
- To assign NMR signals to specific sites within the ZIF-67 structure.
Main Methods:
- Utilized 1H and 13C nuclear magnetic resonance (NMR) spectroscopy.
- Analyzed orbital chemical shifts and paramagnetic effects from cobalt ions.
- Performed first-principles calculations for comparison with experimental data.
Main Results:
- Observed spinning sideband manifolds due to hyperfine interactions between paramagnetic cobalt and NMR-active nuclei.
- Achieved good agreement between experimental and calculated chemical shifts and relaxation rates.
- Demonstrated high-resolution NMR spectra for molecules within the MOF pores.
Conclusions:
- NMR spectroscopy is a powerful tool for the high-confidence assignment of peaks in ZIF-67.
- Fast spin-lattice relaxation rates were observed for guest molecules due to couplings with Co2+ nodes.
- NMR can effectively identify and characterize guest species in MOFs for various applications.
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