Deterioration of western redcedar (Thuja plicata Donn ex D. Don) seeds: protein oxidation and in vivo NMR monitoring of storage oils

Deterioration of conifer seeds during prolonged storage has a negative impact on reforestation and gene conservation efforts. Western redcedar (Thuja plicata Donn ex D. Don) is a species of tremendous value to the forest industry. The seeds of this species are particularly prone to viability losses during long-term storage. Reliable tools to assess losses in seed viability during storage and their underlying causes, as well as the development of methods to prevent storage-related deterioration of seeds are needed by the forest industry. In this work, various imaging methods and biochemical analyses were applied to study deterioration of western redcedar seeds. Seedlots that exhibited poor germination performance, i.e. those that had experienced the greatest losses of viability during prolonged storage, exhibited greater abundance of oxidized proteins, detected by protein oxidation assays, and more pronounced changes in their in vivo (13)C NMR spectra, most likely due to storage oil oxidation. The proportion of oxidized proteins also increased when seeds were subjected to accelerated ageing treatments. Detection of oxidized oils and proteins may constitute a reliable and useful tool for the forest industry

Welcoming gallium- and indium-fumarate MOFs to the family:synthesis, comprehensive characterization, observation of porous hydrophobicity, and CO₂ dynamics

The properties and applications of metal–organic frameworks (MOFs) are strongly dependent on the nature of the metals and linkers, along with the specific conditions employed during synthesis. Al-fumarate, trademarked as Basolite A520, is a porous MOF that incorporates aluminum centers along with fumarate linkers and is a promising material for applications involving adsorption of gases such as CO2. In this work, the solvothermal synthesis and detailed characterization of the gallium- and indium-fumarate MOFs (Ga-fumarate, In-fumarate) are described. Using a combination of powder X-ray diffraction, Rietveld refinements, solid-state NMR spectroscopy, IR spectroscopy, and thermogravimetric analysis, the topologies of Ga-fumarate and In-fumarate are revealed to be analogous to Al-fumarate. Ultra-wideline 69Ga, 71Ga, and 115In NMR experiments at 21.1 T strongly support our refined structure. Adsorption isotherms show that the Al-, Ga-, and In-fumarate MOFs all exhibit an affinity for CO2, with Al-fumarate being the superior adsorbent at 1 bar and 273 K. Static direct excitation and cross-polarized 13C NMR experiments permit investigation of CO2 adsorption locations, binding strengths, motional rates, and motional angles that are critical to increasing adsorption capacity and selectivity in these materials. Conducting the synthesis of the indium-based framework in methanol demonstrates a simple route to introduce porous hydrophobicity into a MIL-53-type framework by incorporation of metal-bridging −OCH3 groups in the MOF pores

SpectroGrid: providing simple secure remote access to scientific instruments

Peer reviewed: YesNRC publication: Ye

In vivo nuclear magnetic resonance metabolite profiling in plant seeds

Peer reviewed: YesNRC publication: Ye

Quadrupolar metal NMR of oxide materials including catalysts

In this work, we review the basic methodology and recent applications of quadrupolar metal solid-state NMR spectroscopy in oxide systems with emphasis on materials science and catalysis. Three typical quadrupolar metal nuclei, 51V, 93Nb, and 95Mo, are discussed in detail to illustrate the complex interplay between the quadrupolar and chemical shielding interactions in oxides. In the first part, a systematic overview is given of the metal coordination environments in oxides and their corresponding NMR parameters. The importance of quantum chemical calculations in correlating experimental NMR results with a molecular level oxide structure is highlighted. In the second part, we present examples of quadrupolar metal NMR in materials science, including paramagnetic oxide systems, layered materials, ferroelectrics, silicates, and glasses. The final section is dedicated to the latest applications of NMR in heterogeneous oxide catalysis.Peer reviewed: YesNRC publication: Ye

A natural abundance 33S solid-state NMR study of layered transition metal disulfides at ultrahigh magnetic field

Using a series of layered transition metal disulfides we demonstrate that the wide-line natural abundance solid-state NMR spectra of 33S in a less symmetric environment can readily be obtained at ultrahigh magnetic field of 21.1 T and that surprisingly these closely related materials display a wide range of 33S quadrupole coupling constant and chemical shift anisotropy values.Peer reviewed: NoNRC publication: Ye

Perspectives of fast magic-angle spinning 87^{87}Rb NMR of organic solids at high magnetic fields

See also:Erratum: "Perspectives of fast magic-angle spinning 87 Rb NMR of organic solids at high magnetic fields".Wu G., Terskikh V., Wong A., in : Magn. Reson. Chem. 2021 Sep;59(9-10):1101. doi: 10.1002/mrc.5198.International audienceWe report solid-state $^{87}$Rb NMR spectra from two Rb-ionophore complexes obtained with fast magic-angle spinning (MAS) (up to 60 kHz) at 21.1 T. These Rb-ionophore complexes containing macrocycles such as benzo-15-crown-5 and cryptand [2.2.2] are typical of organic Rb salts that exhibit very large $^{87}$Rb quadrupole coupling constants (close to 20 MHz). We have also obtained static $^{87}$Rb NMR spectra for these two compounds and determined both $^{87}$Rb quadrupole coupling and chemical shift tensors. The experimental 87Rb NMR tensor parameters are compared with those obtained by quantum chemical computations. Our results demonstrate that the combination of fast MAS (60 kHz or higher) and a high magnetic field (21.1 T or higher) is sufficient to produce high-quality solid-state $^{87}$Rb NMR spectra for organic Rb solids at the natural abundance level. We anticipate that, with additional $^{87}$Rb isotope enrichment (up to 99%), the sensitivity of solid-state $^{87}$Rb NMR will be 400 times higher than $^{39}$K NMR, which makes the former an attractive surrogate probe for studying K$^+$ ion binding in biological systems

Experimental verification of the theory of nuclear quadrupole relaxation in liquids over the entire range of molecular tumbling motion

Nuclear magnetic resonance (NMR) spectra of quadrupolar nuclei (I > 1/2) in liquids often consist of broad resonances, making it difficult to obtain useful chemical information. The poor NMR spectral resolution commonly observed for quadrupolar nuclei is a direct consequence of nuclear quadrupole relaxation processes. Although all key aspects of nuclear quadrupole relaxation processes have been known for decades within the framework of the Redfield relaxation theory, direct experimental NMR relaxation data that cover a wide range of molecular motion in liquids for quadrupolar nuclei are generally lacking. Here we report a complete set of experimental nuclear quadrupole relaxation data that are obtained for 17O, a half-integer quadrupolar nucleus, over the entire range of molecular motion within the limit of the Redfield theory. A general approach utilizing the quadrupole relaxation properties in the slow motion limit will be particularly beneficial for studies of quadrupolar nuclei in biomolecules of medium and large sizes.Peer reviewed: YesNRC publication: Ye

Solid-State 17O NMR Spectroscopy of Large Protein-Ligand Complexes

Peer reviewed: YesNRC publication: Ye