| Autor: |
Martins V; Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada., 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, People's Republic of China., Wang X; National High Magnetic Field Laboratory (NHMFL), 1800 East Paul Dirac Dr., Tallahassee, Florida 32310, United States., Chen K; National High Magnetic Field Laboratory (NHMFL), 1800 East Paul Dirac Dr., Tallahassee, Florida 32310, United States., Hung I; National High Magnetic Field Laboratory (NHMFL), 1800 East Paul Dirac Dr., Tallahassee, Florida 32310, United States., Gan Z; National High Magnetic Field Laboratory (NHMFL), 1800 East Paul Dirac Dr., Tallahassee, Florida 32310, United States., Gervais C; Sorbonne Université, CNRS, UMR 7574, Laboratoire de Chimie de la Matière Condensée de Paris, LCMCP, F-75005 Paris, France., Bonhomme C; Sorbonne Université, CNRS, UMR 7574, Laboratoire de Chimie de la Matière Condensée de Paris, LCMCP, F-75005 Paris, France., Jiang S; 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, People's Republic of China., Zheng A; State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China., Lucier BEG; Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada., Huang Y; Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada. |
| Abstrakt: |
The spectroscopic study of oxygen, a vital element in materials, physical, and life sciences, is of tremendous fundamental and practical importance. 17 O solid-state NMR (SSNMR) spectroscopy has evolved into an ideal site-specific characterization tool, furnishing valuable information on the local geometric and bonding environments about chemically distinct and, in some favorable cases, crystallographically inequivalent oxygen sites. However, 17 O is a challenging nucleus to study via SSNMR, as it suffers from low sensitivity and resolution, owing to the quadrupolar interaction and low 17 O natural abundance. Herein, we report a significant advance in 17 O SSNMR spectroscopy. 17 O isotopic enrichment and the use of an ultrahigh 35.2 T magnetic field have unlocked the identification of many inequivalent carboxylate oxygen sites in the as-made and activated phases of the metal-organic framework (MOF) α-Mg 3 (HCOO) 6 . The subtle 17 O spectral differences between the as-made and activated phases yield detailed information about host-guest interactions, including insight into nonconventional O···H-C hydrogen bonding. Such weak interactions often play key roles in the applications of MOFs, such as gas adsorption and biomedicine, and are usually difficult to study via other characterization routes. The power of performing 17 O SSNMR experiments at an ultrahigh magnetic field of 35.2 T for MOF characterization is further demonstrated by examining activation of the MIL-53(Al) MOF. The sensitivity and resolution enhanced at 35.2 T allows partially and fully activated MIL-53(Al) to be unambiguously distinguished and also permits several oxygen environments in the partially activated phase to be tentatively identified. This demonstration of the very high resolution of 17 O SSNMR recorded at the highest magnetic field accessible to chemists to date illustrates how a broad variety of scientists can now study oxygen-containing materials and obtain previously inaccessible fine structural information. |
