The application of benchtop NMR for investigating the performance of H₂S scavengers

Highly Selective Carbon‐Supported Boron for Oxidative Dehydrogenation of Propane

“…2D 11 B triple‐quantum multiple‐quantum magic‐angle spinning (3Q‐MQMAS) NMR experiments were performed on the fresh and spent catalysts to identify all boron species. This is because the indirect dimension of a 2D MQMAS spectrum reveals NMR signals that are free of second‐order quadrupolar broadening and the peak positions are determined by the isotropic chemical shift (δ iso ) and quadrupolar induced shift (QIS) [61–63] . The 2D 11 B 3Q‐MQMAS NMR spectra of fresh and spent B/OAC are near identical, further suggesting that similar species are present before and after catalysis (Figure 4b–c).…”

Organic NMR crystallography: enabling progress for applications to pharmaceuticals and plant cell walls

“…The creation of DQ coherence between two 1 H spins relies on a dipolar coupling between the two spins, with the dipolar coupling having an inverse cubed dependence on the internuclear distance: the presence or absence of DQ correlation peaks is indicative of the close proximity, typically up to 3.5 Å, or not of two hydrogen atoms. 97,104,105 Consider the two highest ppm 1 H resonances at 12.8 and 13.6 ppm corresponding to the H7 and H1 NH, for which strong 14 N-1 H correlation peaks were observed in Figure 1. For the H7 SQ 1 H resonance, there is one pair of DQ peaks at 12.8 + 8.4 = 21.2 ppm, while for the H7 SQ a The proximities were extracted from the DFT geometry-optimised (CASTEP) crystal structure of 1 (CCDC 2352028).…”

Opportunities and Challenges in Applying Solid‐State NMR Spectroscopy in Organic Mechanochemistry

“…Examples of the application of solid‐state NMR approach on several co‐crystals and complexes have been early reported, where general state‐of‐the‐art 1 H‐detected solid‐state NMR methods for structural characterization are described. [ 97,98 ] Here, as soon as deshielded hydrogen‐bonded protons are detected, a typical solid‐state NMR toolbox for co‐crystal investigation (e.g., employing NMR crystallography, see above) includes both 1 H‐ 1 H homonuclear based experiments, such as Double‐Quantum (DQ) MAS NMR, [ 99 ] as well as 1 H‐including heteronuclear approaches, in which at moderate MAS frequencies (<60 kHz) the X‐nucleus is detected. As an example, informative experiments include 1 H‐ 13 C HETCOR [ 100 ] for the determination of hydrogen donors and acceptors and the characterization of molecular association [ 97,101 ] and 1 H‐ 14 N HMQC [ 102 ] to detect intermolecular ‐N ··· H‐ hydrogen bonds.…”