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Natural abundance oxygen-17 solid-state NMR of metal organic frameworks enhanced by dynamic nuclear polarization
Abstract : The 17 O resonances of Zirconium-oxo clusters that can be found in porous Zr carboxylate metal-organic frameworks (MOFs) have been investigated by magic-angle spinning (MAS) NMR spectroscopy enhanced by dynamic nuclear polarization (DNP). High-resolution 17 O spectra at 0.037 % natural abundance could be obtained in 48 hours, thanks to DNP enhancement of the 1 H polarization by factors = S with /S without = 28, followed by 1 H 17 O cross-polarization, allowing a saving in experimental time by a factor of ca. 800. The distinct 17 O sites from the oxo-clusters can be resolved at 18.8 T. Their assignment is supported by density functional theory (DFT) calculations of chemical shifts and quadrupolar parameters. Protonation of 17 O sites seems to be leading to large characteristic shifts. Markedly, natural abundance 17 O NMR spectra of diamagnetic MOFs can thus be used to probe and characterize the local environment of different 17 O sites on an atomic scale.
https://hal-cnrs.archives-ouvertes.fr/hal-03453303
Contributor : Georges Mouchaham Connect in order to contact the contributor
Submitted on : Sunday, November 28, 2021 - 8:04:52 AM
Last modification on : Tuesday, January 4, 2022 - 6:07:11 AM
Contributor : Georges Mouchaham Connect in order to contact the contributor
Submitted on : Sunday, November 28, 2021 - 8:04:52 AM
Last modification on : Tuesday, January 4, 2022 - 6:07:11 AM
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