31P chemical-shift tensors in barium diethyl phosphate and urea-phosphoric acid: model compounds for phospholipid head-group studies

Biochemistry ◽  
1978 ◽  
Vol 17 (14) ◽  
pp. 2711-2718 ◽  
Author(s):  
J. Herzfeld ◽  
R. G. Griffin ◽  
R. A. Haberkorn
Keyword(s):  
Chemical Shift ◽  
Phosphoric Acid ◽  
Head Group ◽  
Model Compounds ◽  
Chemical Shift Tensors ◽  
Diethyl Phosphate

scholarly journals Modeling Small Structural and Environmental Differences in Solids with 15 N NMR Chemical Shift Tensors

ChemPhysChem ◽  
2021 ◽  
Author(s):  
Luther Wang ◽  
Alexander B. Elliott ◽  
Sean D. Moore ◽  
Gregory J. O. Beran ◽  
Joshua D. Hartman ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Nmr Chemical Shift ◽  
Chemical Shift Tensors

scholarly journals Chemical-shift tensors of heavy nuclei in network solids: a DFT/ZORA investigation of 207Pb chemical-shift tensors using the bond-valence method

2015 ◽  
Vol 17 (38) ◽  
pp. 25014-25026 ◽  
Author(s):  
Fahri Alkan ◽  
C. Dybowski
Keyword(s):  
Chemical Shift ◽  
Quantum Chemistry ◽  
Principal Components ◽  
Bond Valence ◽  
Cluster Models ◽  
Magnetic Shielding ◽  
Heavy Nuclei ◽  
Chemical Shift Tensors ◽  
Accurate Computation ◽  
Bond Valence Model

Accurate computation of 207Pb magnetic shielding principal components is within the reach of quantum chemistry methods by employing relativistic ZORA/DFT and cluster models adapted from the bond valence model.

Determination of chemical shifts in 6-condensed syringylic lignin model compounds

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lucas Lagerquist ◽  
Jani Rahkila ◽  
Patrik Eklund
Keyword(s):  
Chemical Shift ◽  
Methoxy Group ◽  
Chemical Shifts ◽  
Model Compounds ◽  
Correlation Peak ◽  
Lignin Model Compounds ◽  
Benzylic Alcohols ◽  
Lignin Model ◽  
C Nmr

Abstract A small library of 6-substituted syringyl model compounds with aliphatic, carboxylic, phenylic, benzylic alcohols and brominated substituents were prepared. The influence of the substituents on the chemical shifts of the compounds was analyzed. All of model compounds showed a characteristic increase in the 13C NMR chemical shift of the methoxy group vicinal to the substitution. This 13C NMR peak and its corresponding correlation peak in HSQC could potentially be used to identify 6-condensation in syringylic lignin samples.

scholarly journals Elucidating Tricin-Lignin Structures: Assigning Correlations in HSQC Spectra of Monocot Lignins

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 916 ◽  
Author(s):  
Wu Lan ◽  
Fengxia Yue ◽  
Jorge Rencoret ◽  
José del Río ◽  
Wout Boerjan ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Model Compounds ◽  
Heteronuclear Correlation ◽  
Nmr Methods ◽  
Nuclear Magnetic ◽  
Lignin Structure

Tricin [5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one] is a flavone that has been found to be incorporated in grass lignin polymers via 4′–O–β coupling. Herein, we investigated the tricin-lignin structure using nuclear magnetic resonance (NMR) methods by comparing the 1H–13C heteronuclear correlation (HSQC) NMR spectra of the isolated lignin with a series of dimeric and trimeric tricin-4′–O–β-ether model compounds. Results showed that the tricin moiety significantly affects the chemical shift of the Cβ/Hβ of 4′–O–β unit, producing peaks at around δC/δH 82.5–83.5/4.15–4.45, that differ from the Cβ/Hβ correlations from normal 4–O–β units formed solely by monolignols, and that have to date been unassigned.

Local-structure effects on 31P NMR chemical shift tensors in solid state

2019 ◽  
Vol 150 (14) ◽  
pp. 144706 ◽  
Author(s):  
Ivan Yu. Chernyshov ◽  
Mikhail V. Vener ◽  
Ilya G. Shenderovich
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Local Structure ◽  
31P Nmr ◽  
Nmr Chemical Shift ◽  
Chemical Shift Tensors

Are the amide bonds in N-acyl imidazoles twisted? A combined solid-state 17O NMR, crystallographic, and computational study

2015 ◽  
Vol 93 (4) ◽  
pp. 451-458 ◽  
Author(s):  
Xianqi Kong ◽  
Aaron Tang ◽  
Ruiyao Wang ◽  
Eric Ye ◽  
Victor Terskikh ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Crystal Structures ◽  
Computational Study ◽  
Chemical Shifts ◽  
Amide Bond ◽  
Chemical Shift Tensors ◽  
Amide Bonds ◽  
Bond Rotation ◽  
Quadrupole Coupling

We report synthesis of 17O-labeling and solid-state 17O NMR measurements of three N-acyl imidazoles of the type R-C(17O)-Im: R = p-methoxycinnamoyl (MCA-Im), R = 4-(dimethylamino)benzoyl (DAB-Im), and R = 2,4,6-trimethylbenzoyl (TMB-Im). Solid-state 17O NMR experiments allowed us to determine for the first time the 17O quadrupole coupling and chemical shift tensors in this class of organic compounds. We also determined the crystal structures of these compounds using single-crystal X-ray diffraction. The crystal structures show that, while the C(O)–N amide bond in DAB-Im exhibits a small twist, those in MCA-Im and TMB-Im are essentially planar. We found that, in these N-acyl imidazoles, the 17O quadrupole coupling and chemical shift tensors depend critically on the torsion angle between the conjugated acyl group and the C(O)–N amide plane. The computational results from a plane-wave DFT approach, which takes into consideration the entire crystal lattice, are in excellent agreement with the experimental solid-state 17O NMR results. Quantum chemical computations also show that the dependence of 17O NMR parameters on the Ar–C(O) bond rotation is very similar to that previously observed for the C(O)–N bond rotation in twisted amides. We conclude that one should be cautious in linking the observed NMR chemical shifts only to the twist of the C(O)–N amide bond.

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