13C pNMR of “crumple zone” Cu(II) isophthalate metal-organic frameworks
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NMR spectroscopy of paramagnetic materials (pNMR) has the potential to provide great structural insight, but many challenges remain in interpreting the spectra in detail. This work presents a study of a series of structurally analogous metal-organic frameworks (MOFs) based on 5-substituted isophthalate linkers and Cu(II) paddlewheel dimers, of interest owing to their “crumple zone” structural rearrangement on dehydration/rehydration. 13C MAS NMR spectra of the MOFs reveal a wide variation in the observed resonance position for chemically similar C species in the different MOFs but, despite this, resonances are overlapped in several cases. However, by considering a combination of the integration of quantitative spectra, the resonance position as a function of temperature and T1 relaxation measurements, the spectra can be fully assigned. It is also demonstrated that the prototypical MOF in this series, STAM-1, displays a similar crumple zone rearrangement on dehydration to the well-characterised 5-ethoxyisophthalate MOF (STAM-17-OEt) although, while the materials have similar local C environments, dehydrated STAM-1 exhibits less long-range order.
Dawson , D M , Sansome , C E F , McHugh , L N , McPherson , M J , McCormick McPherson , L J , Morris , R E & Ashbrook , S E 2019 , ' 13 C pNMR of “crumple zone” Cu(II) isophthalate metal-organic frameworks ' , Solid State Nuclear Magnetic Resonance , vol. In press . https://doi.org/10.1016/j.ssnmr.2019.05.005
Solid State Nuclear Magnetic Resonance
Copyright © 2019 Elsevier Inc. All rights reserved. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.ssnmr.2019.05.005
DescriptionSEA thanks the Royal Society and Wolfson Foundation for a merit award. REM and LNM thank the EPSRC for support (EP/N50936X/1).
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