Superstructure of a Substituted Zeolitic Imidazolate Metal–Organic Framework Determined by Combining Proton Solid‐State NMR Spectroscopy and DFT Calculations

Abstract

We report the supercell crystal structure of a ZIF-8 analog substituted imidazolate metal-organic framework (SIM-1) obtained by combining solid-state nuclear magnetic resonance and powder X-ray diffraction experiments with density functional theory calculations.

Fast synthesis of zeolitic imidazolate framework ZIF-94 using NaOH and recycling reagents

“…Figure 3A depicts the XRD patterns of all the products obtained by method A that are consistent with the simulated pattern. 38 This confirms high crystallinity of the samples and that all the materials share the SOD type structure corresponding to ZIF-94. 38 The thermal stability was determined by TGA (Figure 3B), where two weight losses can be appreciated.…”

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

“…1 H SSNMR can be employed to obtain detailed structural data that is truly complementary to XRD, yet this characterization route is not straightforward due to strong 1 H‐ 1 H homonuclear dipolar coupling that can severely broaden spectra, which arises from the spatial density of hydrogen in MOFs along with the very high 1 H gyromagnetic ratio (γ). Using high‐resolution 1 H SSNMR techniques it is possible to obtain well‐resolved 1 H resonances in MOFs, including those from chemically different species such as phenyl, methyl, amine, and hydroxyl groups. A more challenging situation arises when there are chemically identical but crystallographically non‐equivalent hydrogen atoms; in this situation, the similar 1 H chemical shifts (CSs) and strong 1 H‐ 1 H dipolar coupling result in very complicated lineshapes and overlapping resonances within a narrow CS range that cannot be resolved.…”

Structural Studies of Polyaramid Fibers: Solid-State NMR and First-Principles Modeling

“…However, in the literature depending on the method used and the nucleus studied, a small deviation from a linear slope of unity is observed. − While in the earlier literature this issue was often discussed or both methods were considered, in more recent literature it is often dismissed and the chemical shifts are related by an enforced slope of unity. − It was also discussed to calculate, similar to an external reference in the solid-state NMR experiments, a reference compound to relate to . However, since these compounds are often very mobile (TMS, adamantane), this is also prone to errors.…”