A new NMR crystallographic approach to reveal the calcium local structure of atorvastatin calcium

2019 ◽  
Vol 21 (12) ◽  
pp. 6319-6326 ◽  
Author(s):  
Sean T. Holmes ◽  
Wei D. Wang ◽  
Guangjin Hou ◽  
Cecil Dybowski ◽  
Wei Wang ◽  
...  
Keyword(s):  
Local Structure ◽  
Solid State Nmr ◽  
Euler Angles ◽  
Coordination Environment ◽  
Chemical Shift Tensors ◽  
Atorvastatin Calcium ◽  
Nmr Parameters ◽  
Quadrupolar Coupling ◽  
Ligand Coordination

We combine experimental and computational determination of 43Ca solid-state NMR parameters (chemical shift tensors, quadrupolar coupling tensors, and Euler angles) to constrain the structure of the local calcium–ligand coordination environment.

Cobalt-59 chemical shift and quadrupolar tensors of simple octahedral cobalt(III) complexes

2001 ◽  
Vol 79 (3) ◽  
pp. 296-303
Author(s):  
Christopher W Kirby ◽  
William P Power
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Principal Components ◽  
Solid State Nmr ◽  
Nmr Spectra ◽  
Line Shapes ◽  
Quadrupolar Coupling ◽  
Molecular Frame ◽  
Specific Ligand

Analysis of the solid-state powder 59Co NMR spectra of ten simple inorganic cobalt(III) complexes at 11.75, and in most cases, 4.7 T have permitted the assignment of specific ligand planes to ranges of values of the observed chemical shift principal components. The relevant chemical shift components were determined from the simulations of the powder line shapes. These simulations also provided the relative orientations of the chemical shift (CS) and electric field gradient (efg) tensors, as well as magnitude and asymmetry of the 59Co quadrupolar coupling. Using symmetry arguments and ab initio calculations, as appropriate or necessary, the orientations of the efg tensors in the molecular frame were deduced. This allowed the determination of the CS tensors in the molecular frame and thus assignment of the ligand planes responsible for the observed values of chemical shifts.Key words: cobalt, chemical shift, quadrupolar coupling, solid state NMR.

scholarly journals Efficient polynomial analysis of MAS spinning sidebands and application to order parameter determination in anisotropic samples

2021 ◽  
Author(s):  
Günter Hempel ◽  
Paul Sotta ◽  
Didier R. Long ◽  
Kay Saalwächter
Keyword(s):  
Solid State Nmr ◽  
Order Parameter ◽  
Magic Angle Spinning ◽  
Parameter Determination ◽  
Magic Angle ◽  
Chemical Shift Tensors ◽  
Fitting Procedure ◽  
The Common ◽  
Angle Spinning

Abstract. Chemical shift tensors in 13C solid-state NMR provide valuable localized information on the chemical bonding environment in organic matter, and deviations from isotropic static-limit powder lineshapes sensitively encode dynamic-averaging or orientation effects. Studies in 13C natural abundance require magic-angle spinning (MAS), where the analysis must thus focus on spinning sidebands. We propose an alternative fitting procedure for spinning sidebands based upon a polynomial expansion that is more efficient 5 than the common numerical solution of the powder average. The approach plays out its advantages in the determination of CST principal values from spinning-sideband intensities and order parameters in non-isotropic samples, which is here illustrated on the example of stretched glassy polycarbonate.

Determination Of Aluminum Coordination Environments In Amorphous AI2O3 By Solid State Nmr Spectroscopy

1993 ◽  
Vol 321 ◽  
Author(s):  
William S. Rees ◽  
Lamy J. Chopin
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Microstructural Development ◽  
Coordination Environment ◽  
Solid State Nmr Spectroscopy ◽  
Recent Developments ◽  
Nmr Techniques

ABSTRACTIt previously has been difficult to probe the localized coordination environment of aluminum atoms in amorphous alumina samples by solid state NMR spectroscopy. Such an in situ technique has benefits in probing the structure of the material and monitoring the evolution of the microstructural development during thermal processing. The recent developments of more sophisticated NMR techniques by Pines, et al., specifically devised for treatment of problems unique to the solid state spectroscopy of quadrupolar nuclei, have permitted a glimpse into these Materials. As a result of applying these experimental techniques to new materials systems, a better understanding of the solid state structure of amorphous aluminas derived from polymer pyrolysis has emerged. Correlations between the onset and completion of crystallization and the localized structure may now be possible.

DETERMINATION OF THE LOCAL STRUCTURE OF METALLIC GLASSES BY EXAFS

1982 ◽  
Vol 43 (C9) ◽  
pp. C9-43-C9-46 ◽  
Author(s):  
A. Sadoc ◽  
A. M. Flank ◽  
D. Raoux ◽  
P. Lagarde
Keyword(s):  
Metallic Glasses ◽  
Local Structure

scholarly journals Relativistic Effects on NMR Parameters of Halogen-Bonded Complexes

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4399 ◽  
Author(s):  
Ibon Alkorta ◽  
José Elguero ◽  
Manuel Yáñez ◽  
Otilia Mó ◽  
M. Merced Montero-Campillo
Keyword(s):  
Relativistic Effects ◽  
Lewis Base ◽  
Coupling Constants ◽  
Basic Site ◽  
Lewis Bases ◽  
Nmr Parameters ◽  
Quadrupolar Coupling ◽  
Binary Complexes ◽  
Computational Level ◽  
Bonded Complexes

Relativistic effects are found to be important for the estimation of NMR parameters in halogen-bonded complexes, mainly when they involve the heavier elements, iodine and astatine. A detailed study of 60 binary complexes formed between dihalogen molecules (XY with X, Y = F, Cl, Br, I and At) and four Lewis bases (NH3, H2O, PH3 and SH2) was carried out at the MP2/aug-cc-pVTZ/aug-cc-pVTZ-PP computational level to show the extent of these effects. The NMR parameters (shielding and nuclear quadrupolar coupling constants) were computed using the relativistic Hamiltonian ZORA and compared to the values obtained with a non-relativistic Hamiltonian. The results show a mixture of the importance of the relativistic corrections as both the size of the halogen atom and the proximity of this atom to the basic site of the Lewis base increase.

Sign in / Sign up

Export Citation Format

Share Document