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submitted on 13.06.2020 and posted on 16.06.2020by Diego Carnevale, Georges Mouchaham, Sujing Wang, Mathieu Baudin, Christian Serre, Geoffrey Bodenhausen, Daniel Abergel
The 17O 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 17O spectra at 0.037
% natural abundance could be obtained in 48 hours, thanks to DNP enhancement of
the 1H polarization by factors e(1H) = Swith/Swithout
= 28, followed by 1H®17O cross-polarization, allowing a
saving in experimental time by a factor of ca.
distinct 17O 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.