Interpretation of cytidine proton chemical shifts and J coupling constants calculated by DFT

2006 ◽  
Vol 767 (1-3) ◽  
pp. 81-85 ◽  
Author(s):  
J.T. Fischer ◽  
S.G. Wehner ◽  
U.M. Reinscheid
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
J Coupling ◽  
J Coupling Constants ◽  
Proton Chemical Shifts

High-Resolution J-Scaling Nuclear Magnetic Resonance Spectra in Inhomogeneous Fields via Intermolecular Multiple-Quantum Coherences

2009 ◽  
Vol 63 (5) ◽  
pp. 585-590 ◽  
Author(s):  
Yanqin Lin ◽  
Zhong Chen ◽  
Shuhui Cai ◽  
Jianhui Zhong
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Chemical Shifts ◽  
Spin Systems ◽  
Coupling Constants ◽  
Multiple Quantum ◽  
J Coupling ◽  
Inhomogeneous Fields ◽  
J Coupling Constants

High-resolution nuclear magnetic resonance (NMR) spectroscopy with information on chemical shifts and J-coupling constants is a sensitive tool for studying physical, chemical, and biological properties of materials at the molecular level. In this paper, a pulse sequence is developed for acquiring high-resolution NMR spectra of liquid samples with J-scaling in inhomogeneous fields via two-dimensional intermolecular multiple-quantum coherence acquisitions. In the resulting one-dimensional projection spectra, apparent J-coupling constants were obtained with a scaling factor theoretically varying from zero (completely decoupled) to infinity relative to the original J-coupling constants while retaining information on chemical shifts, relative peak areas, and multiplet patterns. This allows either an accurate measurement of small J-coupling constants of weakly coupled spin systems or less crowded spectra for spin systems with J-splitting. Experimental observations and simulation results agree with theoretical analysis.

Theoretical studies of the structural, electronic, and 19F NMR properties of linear and branched perfluorobutanesulfonate

2013 ◽  
Vol 91 (12) ◽  
pp. 1272-1280
Author(s):  
Xue Qin Ran ◽  
John D. Goddard
Keyword(s):  
Chemical Shifts ◽  
Polarizable Continuum Model ◽  
Coupling Constants ◽  
Basis Set ◽  
Structural And Electronic Properties ◽  
J Coupling ◽  
Fermi Contact ◽  
J Coupling Constants ◽  
Polarizable Continuum ◽  
Nmr Properties

The structural and electronic properties of linear and branched perfluorobutanesulfonate (PFBS) in its anionic, acidic, and potassium or sodium salt forms were studied in a polarizable continuum model (PCM) of methanol solvent with the B3LYP functional and the 6-31G(d,p) basis set. The 19F chemical shifts and 19F−19F J-coupling constants were determined in a PCM of methanol solvent with GIAO B3LYP/6-31++G(d,p). The differences in energy, enthalpy, and free energy of the four PFBS isomers were compared. The data indicate that the linear PFBS species is less stable than the branched isomers and the isomer with the tert-butyl-like structure is the most stable. The J-coupling contributions via both a non-Fermi contact mechanism and a long chain of bonds (through-bond) indicate that 19F−19F J-coupling constants are long range in these branched PFBS isomers. The calculated and experimental 19F chemical shifts for the linear PFBS species are in good agreement. In addition, the results obtained establish the similarities between the geometries and electronic and NMR properties of linear PFBS and linear perfluorooctanesulfonate (PFOS).

Conformational dynamics detected by nuclear magnetic resonance NOE values and J coupling constants

1988 ◽  
Vol 110 (11) ◽  
pp. 3393-3396 ◽  
Author(s):  
Horst. Kessler ◽  
Christian. Griesinger ◽  
Joerg. Lautz ◽  
Arndt. Mueller ◽  
Wilfred F. Van Gunsteren ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Conformational Dynamics ◽  
Coupling Constants ◽  
J Coupling ◽  
J Coupling Constants ◽  
Nuclear Magnetic

The Molecular Structure of Allenes and Ketenes, XI Semiempirical Calculations of 1H-Chemical Shifts of Allenes

1977 ◽  
Vol 32 (11) ◽  
pp. 1296-1303 ◽  
Author(s):  
W. Runge
Keyword(s):  
Molecular Structure ◽  
Boundary Conditions ◽  
Chemical Shifts ◽  
Quantitative Description ◽  
Algebraic Model ◽  
Coupling Constants ◽  
Semiempirical Calculations ◽  
Proton Coupling ◽  
Nmr Data ◽  
Proton Chemical Shifts

A comparison between calculated and observed values demonstrates that “ansätze” derived from an algebraic model in connection with appropriate boundary conditions are able to account for a quantitative description of the proton chemical shifts of allenes.Correlations of the proton chemical shifts with other NMR data, such as 13C-chemical shifts and one-bond carbon-proton coupling constants, reveal some insigths into the nature of the 1H substituent chemical shifts of alienes.

Studies related to antitumor antibiotics. Part XXIV. High field 1H nmr analysis and conformations of saframycins A and C

1981 ◽  
Vol 59 (20) ◽  
pp. 2945-2952 ◽  
Author(s):  
J. William Lown ◽  
Alummoottil V. Joshua ◽  
Hsiao-Hsiung Chen
Keyword(s):  
High Field ◽  
Chemical Shifts ◽  
Molecular Geometry ◽  
Coupling Constants ◽  
Cytotoxic Action ◽  
Antitumor Antibiotics ◽  
Dna Templates ◽  
H Nmr ◽  
Proton Chemical Shifts ◽  
Unambiguous Assignment

A detailed analysis of the high field (400 MHz) 1H nmr spectra of the basic antitumor antibiotics saframycin A and C in CDCl3, C6D6, and in aqueous DMSO solutions has been carried out. Selective double irradiation experiments permitted the unambiguous assignment of all the proton chemical shifts and coupling constants. Consideration of the magnitudes of the latter together with specific nOe experiments permits assignment of molecular geometry and average conformations in solution. Selective shifts occurring in DMSO–D2O solutions upon addition of CF3COOD identified the 12-N atom as the site of protonation which result bears directly on the acid promoted binding of these antibiotics to DNA templates as part of their cytotoxic action.

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