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Fusco E, Ashbrook SE, Bühl M. 13C pNMR shifts of MOFs based on Cu(II)-paddlewheel dimers - DFT predictions for spin-1/2 defects. Phys Chem Chem Phys 2023; 25:31898-31906. [PMID: 37971425 DOI: 10.1039/d3cp04618d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
We present DFT predictions (CAM-B3LYP/II level) for the paramagnetic Nuclear Magnetic Resonance (pNMR) spectra of small molecular models based on the Cu(II)-paddlewheel dimer motif that is present in metal-organic frameworks (MOFs, notably the HKUST and STAM families). We explore potential point defects with spin-1/2 discovered through electron paramagnetic resonance (EPR) experiments. We consider defects through substitution of one Cu(II) centre in the dimer with protons, or through one-electron reduction, affording a mixed-valence dimer. While most of the defects have predicted pNMR shifts at room temperature in the range of those for the non-defective MOFs, their detection and assignment should be possible based on their distinct temperature dependence.
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Affiliation(s)
- Edoardo Fusco
- EaStCHEM School of Chemistry and Centre of Magnetic Resonance, University of St Andrews, Fife KY16 9ST, UK.
| | - Sharon E Ashbrook
- EaStCHEM School of Chemistry and Centre of Magnetic Resonance, University of St Andrews, Fife KY16 9ST, UK.
| | - Michael Bühl
- EaStCHEM School of Chemistry and Centre of Magnetic Resonance, University of St Andrews, Fife KY16 9ST, UK.
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Xu J, Liu X, Liu X, Yan T, Wan H, Cao Z, Reimer JA. Deconvolution of metal apportionment in bulk metal-organic frameworks. SCIENCE ADVANCES 2022; 8:eadd5503. [PMID: 36332019 PMCID: PMC9635837 DOI: 10.1126/sciadv.add5503] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
We report a general route to decipher the apportionment of metal ions in bulk metal-organic frameworks (MOFs) by solid-state nuclear magnetic resonance spectroscopy. We demonstrate this route in Mg1-xNix-MOF-74, where we uncover all eight possible atomic-scale Mg/Ni arrangements through identification and quantification of the distinct chemical environments of 13C-labeled carboxylates as a function of the Ni content. Here, we use magnetic susceptibility, bond pathway, and density functional theory calculations to identify local metal bonding configurations. The results refute the notion of random apportionment from solution synthesis; rather, we reveal that only two of eight Mg/Ni arrangements are preferred in the Ni-incorporated MOFs. These preferred structural arrangements manifest themselves in macroscopic adsorption phenomena as illustrated by CO/CO2 breakthrough curves. We envision that this nondestructive methodology can be further applied to analyze bulk assembly of other mixed-metal MOFs, greatly extending the knowledge on structure-property relationships of MOFs and their derived materials.
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Affiliation(s)
- Jun Xu
- Tianjin Key Lab for Rare Earth Materials and Applications, School of Materials Science and Engineering and National Institute for Advanced Materials, Nankai University, Tianjin 300350, P.R. China
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Xingwu Liu
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P.R. China
- National Energy Center for Coal to Clean Fuels, Synfuels China Co. Ltd., Huairou District, Beijing 101400, P.R. China
| | - Xingchen Liu
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Tao Yan
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P.R. China
- National Energy Center for Coal to Clean Fuels, Synfuels China Co. Ltd., Huairou District, Beijing 101400, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Hongliu Wan
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P.R. China
- National Energy Center for Coal to Clean Fuels, Synfuels China Co. Ltd., Huairou District, Beijing 101400, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Zhi Cao
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P.R. China
- National Energy Center for Coal to Clean Fuels, Synfuels China Co. Ltd., Huairou District, Beijing 101400, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Jeffrey A. Reimer
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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