Elucidation of correlated disorder in zeolite IM-18

2019 ◽  
Vol 75 (3) ◽  
pp. 333-342 ◽  
Author(s):  
Xiaoge Wang ◽  
Yihan Shen ◽  
Rongli Liu ◽  
Xiaolong Liu ◽  
Cong Lin ◽  
...  
Keyword(s):  
Single Crystal ◽  
Polycrystalline Sample ◽  
Simulation Method ◽  
Magic Angle Spinning ◽  
Two Dimensions ◽  
Mas Nmr ◽  
Double Quantum ◽  
Magic Angle ◽  
Disordered Structures ◽  
Angle Spinning

Classical crystallography is based on the translational periodicity of crystals and the analysis of discrete Bragg reflections. However, it is inadequate for determining disordered structures, of which the diffuse scattering is vital to evaluate the disorder level. The correlated disorder of IM-18 presents as zigzag chains arranged in translational periodicity and the double four-ring units randomly distributed along two dimensions. Supercell models regulated by multiple probabilities were systematically built to simulate the single-crystal and powder X-ray diffraction patterns in order to ascertain the specific disorder configuration in the single-crystal or polycrystalline samples of IM-18. The presence of defects in the polycrystalline sample was proved by combining 29Si magic angle spinning (MAS) NMR and 1H–1H double quantum MAS NMR spectra, and was quantitatively explored by the simulation method. The method could also elucidate other disordered structures in polycrystalline or single-crystal samples, despite the presence of defects or multidimensional disorder.

scholarly journals Single-Crystal 31P and 7Li NMR of the Ionic Conductor LiH2PO4

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 302
Author(s):  
Otto E. O. Zeman ◽  
Viktoria Kainz ◽  
Thomas Bräuniger
Keyword(s):  
Single Crystal ◽  
Rotation Axis ◽  
Polycrystalline Sample ◽  
Magic Angle Spinning ◽  
Ionic Conductor ◽  
Dihydrogen Phosphate ◽  
Magic Angle ◽  
Orthorhombic Crystal ◽  
Quadrupolar Coupling ◽  
Angle Spinning

The electronic surroundings of phosphorus and lithium atoms in the ionic conductor lithium dihydrogen phosphate (LDP) have been studied by single-crystal nuclear magnetic resonance (NMR) spectroscopy at room temperature. From orientation-dependent NMR spectra of a large homegrown LDP single crystal, the full 31P chemical shift (CS) and 7Li quadrupole coupling (QC) tensor was determined, using a global fit over three rotation patterns. The resulting CS tensor is characterized by its three eigenvalues: δ 11 P A S = ( 67.0 ± 0.6 ) ppm, δ 22 P A S = ( 13.9 ± 1.5 ) ppm, and δ 33 P A S = ( − 78.7 ± 0.9 ) ppm. All eigenvalues have also been verified by magic-angle spinning NMR on a polycrystalline sample, using Herzfeld–Berger analysis of the rotational side band pattern. The resulting 7Li QC tensor is characterized by its quadrupolar coupling constant χ = Q 33 P A S = ( − 71 ± 1 ) kHz and the two eigenvalues Q 11 P A S = ( 22.3 ± 0.9 ) kHz, and Q 22 P A S = ( 48.4 ± 0.8 ) kHz. The initially unknown orientation of the mounted crystal, expressed by the orientation of the rotation axis in the orthorhombic crystal frame, was included in the global data fit as well, thus obtaining it from NMR data only.

scholarly journals Determination of the Full 207Pb Chemical Shift Tensor of Anglesite, PbSO4, and Correlation of the Isotropic Shift to Lead–Oxygen Distance in Natural Minerals

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Otto Zeman ◽  
Jennifer Steinadler ◽  
Rupert Hochleitner ◽  
Thomas Bräuniger
Keyword(s):  
Chemical Shift ◽  
Single Crystal ◽  
Polycrystalline Sample ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Isotropic Chemical Shift ◽  
Natural Minerals ◽  
Angle Spinning ◽  
Data Acquisition And Processing

The full 207 Pb chemical shift (CS) tensor of lead in the mineral anglesite, PbSO 4 , was determined from orientation-dependent nuclear magnetic resonance (NMR) spectra of a large natural single crystal, using a global fit over two rotation patterns. The resulting tensor is characterised by the reduced anisotropy Δ δ = ( - 327 ± 4 ) ppm, asymmetry η C S = 0 . 529 ± 0 . 002 , and δ i s o = ( - 3615 ± 3 ) ppm, with the isotropic chemical shift δ i s o also verified by magic-angle spinning NMR on a polycrystalline sample. The initially unknown orientation of the mounted single crystal was included in the global data fit as well, thus obtaining it from NMR data only. By use of internal crystal symmetries, the amount of data acquisition and processing for determination of the CS tensor and crystal orientation was reduced. Furthermore, a linear correlation between the 207 Pb isotropic chemical shift and the shortest Pb–O distance in the co-ordination sphere of Pb 2 + solely surrounded by oxygen has been established for a large database of lead-bearing natural minerals.

scholarly journals Single-crystal X-ray diffraction and NMR crystallography of a 1:1 cocrystal of dithianon and pyrimethanil

2017 ◽  
Vol 73 (3) ◽  
pp. 149-156 ◽  
Author(s):  
Ann-Christin Pöppler ◽  
Emily K. Corlett ◽  
Harriet Pearce ◽  
Mark P. Seymour ◽  
Matthew Reid ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Chemical Shifts ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Double Quantum ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Crystallography

A single-crystal X-ray diffraction structure of a 1:1 cocrystal of two fungicides, namely dithianon (DI) and pyrimethanil (PM), is reported [systematic name: 5,10-dioxo-5H,10H-naphtho[2,3-b][1,4]dithiine-2,3-dicarbonitrile–4,6-dimethyl-N-phenylpyrimidin-2-amine (1/1), C14H4N2O2S2·C12H13N2]. Following an NMR crystallography approach, experimental solid-state magic angle spinning (MAS) NMR spectra are presented together with GIPAW (gauge-including projector augmented wave) calculations of NMR chemical shieldings. Specifically, experimental 1H and 13C chemical shifts are determined from two-dimensional 1H–13C MAS NMR correlation spectra recorded with short and longer contact times so as to probe one-bond C—H connectivities and longer-range C...H proximities, whereas H...H proximities are identified in a 1H double-quantum (DQ) MAS NMR spectrum. The performing of separate GIPAW calculations for the full periodic crystal structure and for isolated molecules allows the determination of the change in chemical shift upon going from an isolated molecule to the full crystal structure. For the 1H NMR chemical shifts, changes of 3.6 and 2.0 ppm correspond to intermolecular N—H...O and C—H...O hydrogen bonding, while changes of −2.7 and −1.5 ppm are due to ring current effects associated with C—H...π interactions. Even though there is a close intermolecular S...O distance of 3.10 Å, it is of note that the molecule-to-crystal chemical shifts for the involved sulfur or oxygen nuclei are small.

scholarly journals Combination of solid state NMR and DFT calculation to elucidate the state of sodium in hard carbon electrodes

2016 ◽  
Vol 4 (34) ◽  
pp. 13183-13193 ◽  
Author(s):  
Ryohei Morita ◽  
Kazuma Gotoh ◽  
Mika Fukunishi ◽  
Kei Kubota ◽  
Shinichi Komaba ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Dft Calculation ◽  
Magic Angle Spinning ◽  
The State ◽  
Mas Nmr ◽  
Magic Angle ◽  
Multiple Quantum ◽  
Hard Carbon ◽  
Angle Spinning

We examined the state of sodium electrochemically inserted in HC prepared at 700–2000 °C using solid state Na magic angle spinning (MAS) NMR and multiple quantum (MQ) MAS NMR.

scholarly journals Sampling Method Affects HR-MAS NMR Spectra of Healthy Caprine Brain Biopsies

Metabolites ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 38
Author(s):  
Annakatrin Häni ◽  
Gaëlle Diserens ◽  
Anna Oevermann ◽  
Peter Vermathen ◽  
Christina Precht
Keyword(s):  
Nmr Spectroscopy ◽  
Sampling Method ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
1H Nuclear Magnetic Resonance ◽  
Rapid Changes ◽  
Tissue Degradation ◽  
Angle Spinning

The metabolic profiling of tissue biopsies using high-resolution–magic angle spinning (HR-MAS) 1H nuclear magnetic resonance (NMR) spectroscopy may be influenced by experimental factors such as the sampling method. Therefore, we compared the effects of two different sampling methods on the metabolome of brain tissue obtained from the brainstem and thalamus of healthy goats by 1H HR-MAS NMR spectroscopy—in vivo-harvested biopsy by a minimally invasive stereotactic approach compared with postmortem-harvested sample by dissection with a scalpel. Lactate and creatine were elevated, and choline-containing compounds were altered in the postmortem compared to the in vivo-harvested samples, demonstrating rapid changes most likely due to sample ischemia. In addition, in the brainstem samples acetate and inositols, and in the thalamus samples ƴ-aminobutyric acid, were relatively increased postmortem, demonstrating regional differences in tissue degradation. In conclusion, in vivo-harvested brain biopsies show different metabolic alterations compared to postmortem-harvested samples, reflecting less tissue degradation. Sampling method and brain region should be taken into account in the analysis of metabolic profiles. To be as close as possible to the actual situation in the living individual, it is desirable to use brain samples obtained by stereotactic biopsy whenever possible.

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