Boosting H and C NMR signals by orders of magnitude on a bench.

Sensitivity is often the Achilles' heel of liquid-state nuclear magnetic resonance (NMR) experiments. This problem is perhaps most pressing at the lowest fields (e.g.

Identifying routes for transferring spin polarization from parahydrogen to protic solvents.

Repeatable hyperpolarization of high concentrations of mobile protons (>6 M) using parahydrogen in protic methanol/water mixtures is reported here. Different ammonium buffers with increasing mobile proton concentrations were added to an IrCl(COD)(IMes) catalyst in the presence of pyridine. We reach a maximum molar polarization of 1.

Full optimization of dynamic nuclear polarization on a 1 tesla benchtop polarizer with hyperpolarizing solids.

Hyperpolarization by dissolution dynamic nuclear polarization (dDNP) provides the opportunity to dramatically increase the weak nuclear magnetic resonance (NMR) signal of liquid molecular targets using the high polarization of electron radicals. Unfortunately, the solution-state hyperpolarization can only be accessed once since freezing and melting of the hyperpolarized sample happen in an irreversible fashion. A way to expand the application horizon of dDNP can therefore be to find a recyclable DNP alternative.

Reversible Parahydrogen Induced Hyperpolarization of N in Unmodified Amino Acids Unraveled at High Magnetic Field.

Amino acids (AAs) and ammonia are metabolic markers essential for nitrogen metabolism and cell regulation in both plants and humans. NMR provides interesting opportunities to investigate these metabolic pathways, yet lacks sensitivity, especially in case of N. In this study, spin order embedded in p-H is used to produce on-demand reversible hyperpolarization in N of pristine alanine and ammonia under ambient protic conditions directly in the NMR spectrometer.

Isotopological Fingerprinting Using H/D Scrambling Identifies the Stereochemistry of Hyperpolarization Catalysts Transferring Spin Polarization from Parahydrogen to Substrates Using Signal Amplification by Reversible Exchange.

Hyperpolarization using signal amplification by reversible exchange (SABRE) relies on target molecules and parahydrogen coordinating to a transition metal catalyst. Identification of this coordinated state becomes increasingly important, especially since bio-relevant targets such as pyruvate and amino acids exhibiting multiple binding sites are becoming compatible with SABRE. In this report, we present a fingerprinting method to discriminate and identify ligand binding sites without requiring the presence of a sensitive or isotope-labeled heteroatom.

Long-Term Generation of Longitudinal Spin Order Controlled by Ammonia Ligation Enables Rapid SABRE Hyperpolarized 2D NMR.

The front cover artwork front cover artwork is provided by NMRCoRe, the Flemish NMR/X-Ray platform for Convergence Research and was designed by Ir. Ewoud Vaneeckhaute and Dr. Eric Breynaert.

Long-Term Generation of Longitudinal Spin Order Controlled by Ammonia Ligation Enables Rapid SABRE Hyperpolarized 2D NMR.

Symmetry breaking of parahydrogen using iridium catalysts converts singlet spin order into observable hyperpolarization. In this contribution, iridium catalysts are designed to exhibit asymmetry in their hydrides, regulated by in situ generation of deuterated ammonia governed by ammonium buffers. The concentrations of ammonia (N) and pyridine (P) provide a handle to generate a variety of stereo-chemically asymmetric N-heterocyclic carbene iridium complexes, ligating either [3xP], [2xP;N], [P;2xN] or [3xN] in an octahedral SABRE type configuration.

H Diffusion-Ordered Nuclear Magnetic Resonance Spectroscopic Analysis of Water-Extractable Arabinoxylan in Wheat ( L.) Flour.

The structural heterogeneity of water-extractable arabinoxylan (WE-AX) impacts wheat flour functionality. H diffusion-ordered (DOSY) nuclear magnetic resonance (NMR) spectroscopy revealed structural heterogeneity within WE-AX fractions obtained via graded ethanol precipitation. Combination with high-resolution H-H correlation NMR spectroscopy (COSY) allowed identifying the relationship between the xylose substitution patterns and diffusion properties of the subpopulations.

C-DOSY-TOSY NMR Correlation for In Situ Analysis of Structure, Size Distribution, and Dynamics of Prebiotic Oligosaccharides.

Arabinoxylan oligosaccharides (AXOS) are a complex mixture of cereal derived, water-soluble prebiotics, obtained by enzymatic hydrolysis of arabinoxylan, a group of dietary fibers exerting numerous nutritional and health-beneficial effects. Such complex biomolecular mixtures are notoriously difficult to characterize without initial physical fractionation. Here we present the analysis of AXOS using a variety of state-of-the-art sensitivity-enhanced C-DOSY methods, enabling virtual separation and identification of the components.