Complete multinuclear solid‐state NMR of metal‐organic frameworks: The case of α‐Mg‐formate

Abstract

Metal-organic frameworks (MOFs) are exciting porous materials with a growing number of applications ranging from catalysis to gas storage. Establishing logical connections between the local MOF structure and its properties is not often straightforward, however, solid-state NMR is a sensitive probe of local structure and can be used to shed light on processes such as guest adsorption and gas motion within MOFs. As illustrated using our recent works on the microporous a-Mg-formate (Mg 3 (HCOO) 6 ) MOF, complete multinuclear solid-state NMR characterization of MOFs is now possible, and can provide unique insight that is not readily available through other methods. A wide variety of solid-state NMR techniques have been employed, including direct-excitation, cross-polarization, fast magic-angle spinning, and two-dimensional experiments. New variable-temperature 2 H solid-state NMR data of deuterated hydrogen gas within a-Mg-formate and the resulting detailed dynamic information is also presented, analyzed, and discussed.

Exploring Host–Guest Interactions in the α-Zn3(HCOO)6 Metal-Organic Framework

“…Since α defines the space that CO 2 sweeps through during the rotation, it may be related to the strength of the interaction between CO 2 and hydrogen. 40,66 Thus, a stronger O=C=O···H interaction can result in a smaller wobbling angle. Figure 10 and Table 1 show that the α of CO 2 adsorbed in the MIL-53-based MOFs are remarkably smaller than those in the formate-based MOFs.…”

Solid‐State NMR Spectroscopy: A Powerful Technique to Directly Study Small Gas Molecules Adsorbed in Metal–Organic Frameworks

“…Due to the significant line broadening that results from the presence of strong 1 H‐ 1 H homonuclear dipolar coupling interactions, SSNMR studies are generally performed on deuterium ( 2 H and/or D) instead of 1 H. The quadrupolar nature of 2 H allows for dynamics studies using lineshape analysis, providing a better understanding on the motions of H 2 within MOFs . The first SSNMR study on the dynamics of H 2 within MOFs was performed on UiO‐66, M‐MOF‐74 (M = Zn, Mg, Ni), and α‐M 3 (COOH) 6 (M = Zn, Mg) using D 2 and static VT 2 H SSNMR spectroscopy (Figure ) .…”

“…[28] Due to the significant line broadening that resultsf rom the presence of strong 1 H-1 Hh omonuclear dipolar coupling interactions,S SNMR studies are generally performed on deuterium ( 2 Ha nd/orD )i nsteado f 1 H. The quadrupolar nature of 2 H allows for dynamics studies using lineshape analysis, [23] providing ab etter understanding on the motionso fH 2 within MOFs. [29,30] The first SSNMR study on the dynamics of H 2 within MOFs was performed on UiO-66, M-MOF-74 (M = Zn, Mg, Ni), and a-M 3 (COOH) 6 (M = Zn, Mg) using D 2 and static VT 2 H SSNMR spectroscopy (Figure 4). [29] Variations in H 2 affinity were detected, showingt hat 2 HS SNMRs pectroscopy can be used to correlate MOF structurald ifferences with H 2 binding strength.For instance, the 2 HSSNMR spectra of Zn-MOF-74 dis- Concept played an arrow resonance with ap seudo-Lorentzian lineshape, indicating rapid isotropic tumbling of the D 2 guests.…”

Welcoming Gallium- and Indium-Fumarate MOFs to the Family: Synthesis, Comprehensive Characterization, Observation of Porous Hydrophobicity, and CO2 Dynamics

“…13 C NMR experiments have been used to investigate CO 2 locations, dynamics, and relative binding strengths within MOFs. 35,38,[59][60][61][62][63][64][65][66][67][68][69][70][71][72][73] In this work, we acquired static VT 13 C NMR spectra of CO 2 -loaded Al-fumarate at temperatures ranging from 133 K to 373 K (Figure 11(a)), and those of CO 2 -loaded Ga-fumarate, In-fumarate-E, and In-fumarate-M were acquired at temperatures between 133 K to 293 K (Figure 11(b), (c), (d)); the extracted CS parameters are summarized in Table S7. At 293 K, the static 13 C NMR spectra of 13 CO 2 adsorbed in Al-fumarate features a powder pattern corresponding to a span () of 27(1) ppm and a skew () value equal to +1.…”