DOI: 10.1002/chem.201201563 Characterization of Zn-Containing Metal–Organic Frameworks by Solid- State 67 Zn NMR Spectroscopy and Computational Modeling Andre Sutrisno, [a] Victor V. Terskikh, [b] Qi Shi, [c] Zhengwei Song, [c] Jinxiang Dong,* [c] San Yuan Ding, [d] Wei Wang,* [d] Bianca R. Provost, [e] Thomas D. Daff, [e] Tom K. Woo,* [e] and Yining Huang* [a] Introduction One of the most exciting advances in the field of nanopo- rous materials in recent years is the emergence of a fascinat- ing family of hybrid organic–inorganic solids, known as metal–organic frameworks (MOFs). [1, 2] They have many po- tential industrial and technological applications in the areas of catalysis, ion exchange, sensors, and in particular, gas stor- age and separation. Characterization is important because understanding the relationship between the key properties of these materials and their unique structures is crucial to the development of new applications and the performance improvement of their current uses. Although the structures of many MOFs can be deter- mined by single-crystal X-ray diffraction, a significant number of MOF structures have to be refined from more limited powder XRD data due to the lack of suitable single crystals. [3] In such cases an unambiguous structure solution Abstract: Metal–organic frameworks (MOFs) are an extremely important class of porous materials with many ap- plications. The metal centers in many important MOFs are zinc cations. However, their Zn environments have not been characterized directly by 67 Zn solid-state NMR (SSNMR) spectrosco- py. This is because 67 Zn (I = 5/2) is un- receptive with many unfavorable NMR characteristics, leading to very low sen- sitivity. In this work, we report, for the first time, a 67 Zn natural abundance SSNMR spectroscopic study of several representative zeolitic imidazolate frameworks (ZIFs) and MOFs at an ul- trahigh magnetic field of 21.1 T. Our work demonstrates that 67 Zn magic- angle spinning (MAS) NMR spectra are highly sensitive to the local Zn en- vironment and can differentiate non- equivalent Zn sites. The 67 Zn NMR pa- rameters can be predicted by theoreti- cal calculations. Through the study of MOF-5 desolvation, we show that with the aid of computational modeling, 67 Zn NMR spectroscopy can provide valuable structural information on the MOF systems with structures that are not well described. Using ZIF-8 as an example, we further demonstrate that 67 Zn NMR spectroscopy is highly sensi- tive to the guest molecules present inside the cavities. Our work also shows that a combination of 67 Zn NMR data and molecular dynamics simula- tion can reveal detailed information on the distribution and the dynamics of the guest species. The present work es- tablishes 67 Zn SSNMR spectroscopy as a new tool complementary to X-ray diffraction for solving outstanding structural problems and for determin- ing the structures of many new MOFs yet to come. Keywords: desolvation · host–guest systems · metal–organic frame- works · NMR spectroscopy · solid- state structures · zinc [a] Dr. A. Sutrisno, Prof. Y. Huang Department of Chemistry, The University of Western Ontario London, Ontario, N6A 5B7 (Canada) E-mail: yhuang@uwo.ca [b] Dr. V.V. Terskikh Steacie Institute for Molecular Sciences, National Research Council Ottawa, Ontario, K1A 0R6 (Canada) [c] Q. Shi, Z. Song, Prof. J. Dong Research Institute of Special Chemicals Taiyuan University of Technology Shanxi, Taiyuan 030024 (P.R. China) E-mail : dongjinxiangwork@hotmail.com [d] S.Y. Ding, Prof. W. Wang State Key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical Engineering Lanzhou University, Lanzhou, Gansu, 730000 (P.R. China) E-mail : wang_wei@lzu.edu.cn [e] B. R. Provost, Dr. T. D. Daff, Prof. T.K. Woo Centre for Catalysis Research and Innovation Department of Chemistry, University of Ottawa Ottawa, Ontario, K1N 6N5 (Canada) E-mail: Tom.Woo@uottawa.ca Supporting information for this article (detailed sample preparation; Figure S1–S8—additional 67 Zn static NMR spectra of as-synthesized ZIF-8 at 9.4 and 21.1 T, plots of 67 Zn C Q and span values as a function of varied structural parameters, comparison between 67 Zn experimen- tal and theoretical static NMR spectra of fully desolvated MOF-5 at 21.1 T, schematic of spherical vector used for calculating guest distri- butions, powder XRD pattern and 13 C CPMAS NMR spectra of ZIF samples, atom labeling for ZIF-8; Tables S1–S7—structural data for ZIF samples, list of calculated 67 Zn EFG and CS tensor parameters of MOF-5, list of structural data for MOF-5 from literature and pres- ent work, detailed experimental 67 Zn NMR conditions, Lennard– Jones parameters, partial atomic charges for ZIF-8, number of guest molecules in molecular dynamics simulations) is available on the WWW under http://dx.doi.org/10.1002/chem.201201563. 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