scholarly journals Theoretical 13C chemical shift, 14N, and 2H quadrupole coupling–constant studies of hydrogen bonding for measurement and calculation of 13C and 15N NMR chemical–shift tensors in DNA/RNA of gum cancer cells identification: A powerful alternative

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Alireza Heidari ◽  
Ricardo Gobato ◽  
Lauro Figueroa Valverde
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Shift ◽  
Cancer Cells ◽  
Quadrupole Coupling Constant ◽  
15N Nmr ◽  
Coupling Constant ◽  
Nmr Chemical Shift ◽  
Chemical Shift Tensors ◽  
Quadrupole Coupling ◽  
13C Chemical Shift

Hydrogen Bonding Effects on the13C NMR Chemical Shift Tensors of Some Amino Acids in the Solid State

1997 ◽  
Vol 35 (9) ◽  
pp. 606-608 ◽  
Author(s):  
Guang Zheng ◽  
Liming Wang ◽  
Jianzhi Hu ◽  
Xiaodong Zhang ◽  
Lianfang Shen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Chemical Shift ◽  
Nmr Chemical Shift ◽  
Chemical Shift Tensors

The 59Co nuclear magnetic resonance spectra of polycrystalline complexes

1987 ◽  
Vol 65 (6) ◽  
pp. 1332-1335 ◽  
Author(s):  
Donald R. Eaton ◽  
Richard J. Buist ◽  
Brian G. Sayer
Keyword(s):  
Chemical Shift ◽  
Chemical Shift Anisotropy ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
X Ray ◽  
Low Field ◽  
Nmr Data ◽  
Nuclear Magnetic Resonance Spectra ◽  
Quadrupole Coupling ◽  
Low Field Nmr

The solid state 59Co nmr spectra of a number of octahedral complexes are reported. In the case of sodium hexanitrocobaltate(III) the spectra have been obtained at several different field strengths and the results are analysed to give a quadrupole coupling constant of 9.4 MHz, an asymmetry parameter of zero and an axial chemical shift tensor with an anisotropy of 180 ppm. Several other complexes have been examined at high field (11.8 T) to minimize the effects of quadrupole coupling and maximize the influence of chemical shift anisotropy. The results are, where possible, compared with single crystal X-ray and low field nmr data. It is concluded that high fields are necessary to obtain reliable chemical shift anisotropy values. The conditions necessary for obtaining reasonable quality spectra from polycrystalline samples containing quadrupolar nuclei are discussed.

35Cl AND 37Cl MAGNETIC RESONANCE OF SIMPLE CHLORINE COMPOUNDS

1965 ◽  
Vol 43 (9) ◽  
pp. 2530-2534 ◽  
Author(s):  
Yasukazu Saito
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Quadrupole Coupling Constant ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Reference Compound ◽  
Excitation Energies ◽  
Structural Applications ◽  
Quadrupole Coupling ◽  
Magnetic Resonances

The nuclear magnetic resonances of 35Cl and 37Cl in a number of simple chlorine compounds were measured. Since both the paramagnetic contribution for chemical shift and the quadrupole coupling constant of the atom are determined by the same radial distribution of the electron, a linear relationship between the chemical shifts and the quadrupole coupling constants may be expected for compounds for which the electronic excitation energies are comparable. This was demonstrated for the series of chloro-substituted methanes. By graphical extrapolation the absolute chemical shift of the reference compound, NaCl aqueous solution, was obtained. The chemical shift of Cl− aq. ion can be interpreted as the sum of the diamagnetic shift of Cl− spherical ion and a paramagnetic shift resulting from its hydration. The experimental and theoretical values of the paramagnetic chemical shift of the Cl2 molecule were −2.06 × 10−3 and −2.17 × 10−3, respectively. Paramagnetic chemical shifts and line widths of resonance spectra of simple chlorine compounds are discussed, as well as the feasibility of high-resolution chlorine resonances for structural applications.

15N NMR Chemical Shift Tensors of Substituted Hexaazaisowurtzitanes:  The Intermediates in the Synthesis of CL-20†

2004 ◽  
Vol 108 (14) ◽  
pp. 2638-2644 ◽  
Author(s):  
Jacalyn S. Clawson ◽  
Karen L. Anderson ◽  
Ronald J. Pugmire ◽  
David M. Grant
Keyword(s):  
Chemical Shift ◽  
15N Nmr ◽  
Nmr Chemical Shift ◽  
Chemical Shift Tensors

A solid-state 35/37Cl NMR study of a chloride ion receptor and a GIPAW-DFT study of chlorine NMR interaction tensors in organic hydrochlorides

2011 ◽  
Vol 89 (7) ◽  
pp. 822-834 ◽  
Author(s):  
Rebecca P. Chapman ◽  
Jennifer R. Hiscock ◽  
Philip A. Gale ◽  
David L. Bryce
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Density Functional ◽  
Chloride Ion ◽  
Quadrupole Coupling Constant ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
High Symmetry ◽  
Coupling Constant ◽  
Quadrupole Coupling

The results of a 35/37Cl solid-state nuclear magnetic resonance (SSNMR) study of the 1-butyl-3-methylimidazolium chloride complex of meso-octamethylcalix[4]pyrrole (1) are reported. Line shapes obtained from magic-angle-spinning and stationary powder samples collected at 9.4 and 21.1 T are analyzed to provide the 35/37Cl quadrupolar tensor and chemical shift (CS) tensor and their relative orientation. The relatively high symmetry of the chloride ion coordination environment is manifested in the small value of the quadrupole coupling constant, CQ(35Cl) = 1.0 MHz. The isotropic chemical shift of 120 ppm (with respect to NaCl(s)) is at the upper edge of the typical range seen for organic hydrochlorides. Consideration of chemical shift anisotropy (span, Ω = 50 ppm) and non-coincidence of the quadrupolar and CS tensors were essential to properly simulate the experimental spectra. The utility of gauge-including projector-augmented wave density functional theory (GIPAW-DFT) calculations of chlorine quadrupolar and CS tensors in organic chlorides was explored by validation against available benchmark experimental data for solid amino acid hydrochlorides. The calculations are shown to systematically overestimate the value of the 35Cl quadrupole coupling constant. Additional calculations on various hydrated and solvated models of 1 are consistent with a structure in which solvent and water of hydration are absent.

51V and 93Nb high resolution NMR study of NbVO5

1991 ◽  
Vol 6 (2) ◽  
pp. 393-400 ◽  
Author(s):  
J. Davis ◽  
D. Tinet ◽  
J.J. Fripiat ◽  
J.M. Amarilla ◽  
B. Casal ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Chemical Shift Anisotropy ◽  
Quadrupole Coupling Constant ◽  
Isotropic Chemical Shift ◽  
Coupling Constant ◽  
Nmr Study ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
High Resolution Nmr ◽  
Lower Electric Field

NbVO5 is characterized by 51V and 93Nb NMR resonance frequencies strongly upfield shifted when compared to those in model compounds V2O5 and LiNbO3. The chemical shift anisotropy dominates the 51V observed spectrum in a magnetic field of 11.7 T. The asymmetry parameter ηc is 0.2 and the quadrupole coupling constant is relatively small (1 MHz). The quadrupolar Hamiltonian overwhelmingly dominates the 93Nb spectrum (ηQ = 0.9) and the quadrupole coupling constant is huge (16.5 MHz). In agreement with the structure obtained from the x-ray powder diagram the isotropic chemical shift of 51V suggests that NbVO5 is indeed an orthovanadate. Interestingly, in NbVO5 the isotropic chemical shift of 93Nb reveals a better shielding of the 93Nb nucleus and a lower electric field gradient than in LiNbO3. Nb octahedra in NbVO5 are sharing corners whereas they share edges in LiNbO3.

Measurement and calculation of 13C and 15N NMR chemical-shift tensors of a push–pull ethylene

2009 ◽  
Vol 87 (4) ◽  
pp. 563-570 ◽  
Author(s):  
Saeed K. Amini ◽  
Mohsen Tafazzoli ◽  
Hilary A. Jenkins ◽  
Gillian R. Goward ◽  
Alex D. Bain
Keyword(s):  
Double Bond ◽  
Chemical Shift ◽  
Charge Density ◽  
Density Functional ◽  
The Other ◽  
15N Nmr ◽  
Nmr Chemical Shift ◽  
Strong Electron ◽  
Chemical Shift Tensors ◽  
Donor And Acceptor

Methyl 3-dimethylamino-2-cyanocrotonate (MDACC) has a remarkably weak carbon–carbon double bond. It has strong electron-withdrawing groups on one end and electron-donating groups on the other: a so-called push–pull ethylene. To investigate this unusual electronic structure, we have determined the crystal structure and measured both the 13C and 15N NMR chemical-shift tensors. These measurements are supplemented by shielding-tensor calculations done with density functional methods. The large difference (approximately 100 ppm) between isotropic chemical shifts of the two alkenyl carbons reflects a large charge release from the electron-donating side of C=C double bond to the electron-withdrawing groups. Comparison of the calculated orientations of the principal components of the alkenyl carbons obtained from ab initio calculations shows that the primary changes in charge density occur in the molecular plane. On the other hand, smaller charge density changes above and below the plane of the C=C double bond establish the conjugation of donor and acceptor groups with π* and π molecular orbitals of the central double bond, respectively, which lowers the barrier to rotation about this bond.

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