13 C chemical shift tensors in MOF α-Mg 3 (HCOO) 6 : Which component is more sensitive to host-guest interaction?

Autor: Xu J; Center for Rare Earth and Inorganic Functional Materials, Tianjin Key Lab for Rare Earth Materials and Applications, School of Materials Science and Engineering & National Institute for Advanced Materials, Nankai University, Tianjin, 300350, P.R. China.; Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada., Terskikh VV; Department of Chemistry, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada., Chu Y; Chinese Academy of Sciences, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Wuhan, 430071, P.R. China., Zheng A; Chinese Academy of Sciences, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Wuhan, 430071, P.R. China., Huang Y; Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada.
Jazyk: angličtina
Zdroj: Magnetic resonance in chemistry : MRC [Magn Reson Chem] 2020 Nov; Vol. 58 (11), pp. 1082-1090. Date of Electronic Publication: 2019 Dec 13.
DOI: 10.1002/mrc.4944
Abstrakt: Metal-organic frameworks (MOFs) are a class of important porous materials with many current and potential applications. Their applications almost always involve the interaction between host framework and guest species. Therefore, understanding of host-guest interaction in MOF systems is fundamentally important. Solid-state NMR spectroscopy is an excellent technique for investigating host-guest interaction as it provides information complementary to that obtained from X-ray diffraction. In this work, using MOF α-Mg 3 (HCOO) 6 as an example, we demonstrated that 13 C chemical shift tensor of organic linker can be utilized to probe the host-guest interaction in MOFs. Obtaining 13 C chemical shift tensor components (δ 11 , δ 22 , and δ 33 , where δ 11 ≥ δ 22 ≥ δ 33 ) in this MOF is particularly challenging as there are six coordinatively equivalent but crystallographically non-equivalent carbons in the unit cell with very similar local coordination environment. Two-dimensional magic-angle-turning experiments were employed to measure the 13 C chemical shift tensors of each individual crystallographically non-equivalent carbon in three microporous α-Mg 3 (HCOO) 6 samples with different guest species. The results indicate that the δ 22 component (with its direction approximately being co-planar with the formate anion and perpendicular to the C-H bond) is more sensitive to the adsorbate molecules inside the MOF channel due to the weak C-H···O hydrogen bonding or the ring current effect of benzene. The 13 C isotropic chemical shift, on the other hand, seems much less sensitive to the subtle changes in the local environment around formate linker induced by adsorption. The approach described in this study may be used in future studies on host-guest interaction within MOFs.
(© 2019 John Wiley & Sons, Ltd.)
Databáze: MEDLINE
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