Deriving Accurate Interproton Distances from ROESY Spectra with Limited Knowledge of Scalar Coupling Constants via the CARNIVAL Algorithm. An Iterative Complete-Relaxation-Matrix Approach

1995 ◽  
Vol 107 (1) ◽  
pp. 51-59 ◽  
Author(s):  
H. Liu ◽  
D.L. Banville ◽  
V.J. Basus ◽  
T.L. James
Keyword(s):  
Coupling Constants ◽  
Scalar Coupling ◽  
Matrix Approach ◽  
Limited Knowledge ◽  
Relaxation Matrix ◽  
Complete Relaxation ◽  
Interproton Distances

scholarly journals Accuracy in determining interproton distances using Nuclear Overhauser Effect data from a flexible molecule

2011 ◽  
Vol 7 ◽  
pp. 145-150 ◽  
Author(s):  
Catharine R Jones ◽  
Craig P Butts ◽  
Jeremy N Harvey
Keyword(s):  
Nuclear Overhauser Effect ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Dynamical Analysis ◽  
Flexible Molecules ◽  
Large Numbers ◽  
Distance Restraints ◽  
Nuclear Overhauser ◽  
Interproton Distances

The determination of accurate NOE-derived interproton distances and confirmation/prediction of relative populations in multi-conformer, flexible small molecules was investigated with the model compound 4-propylaniline. The low accuracy assumed for semi-quantitative NOE distance restraints is typically taken to suggest that large numbers of constraints need to be used in the dynamical analysis of flexible molecules, and this requires, for example, the measurement and Karplus-type analysis of scalar coupling constants (3 J CH and 3 J HH). Herein we demonstrate that, contrary to this common perception, NOE measurements alone are accurate enough to establish interproton distances, and hence conformational detail, in flexible molecules to within a few percent of their ensemble-averaged values, hence reducing the demand for additional restraints in such dynamic analyses.

NOE intensities from multiple conformations in solution analyzed by the complete relaxation matrix approach

1998 ◽  
Vol 15 (3-4) ◽  
pp. 401-406 ◽  
Author(s):  
A. Donati ◽  
C. Rossi ◽  
S. Martini ◽  
N. B. Ulyanov ◽  
T. L. James
Keyword(s):  
Matrix Approach ◽  
Relaxation Matrix ◽  
Complete Relaxation ◽  
Multiple Conformations

scholarly journals NMR Properties of the Cyanide Anion, a Quasisymmetric Two-Faced Hydrogen Bonding Acceptor

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1298
Author(s):  
Ilya G. Shenderovich ◽  
Gleb S. Denisov
Keyword(s):  
Hydrogen Bonding ◽  
Experimental Studies ◽  
Polarizable Continuum Model ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Cyanide Anion ◽  
Molecular Systems ◽  
Polarizable Continuum ◽  
Chemical Shieldings ◽  
Nmr Properties

The isotopically enriched cyanide anion, (13C≡15N)−, has a great potential as the NMR probe of non-covalent interactions. However, hydrogen cyanide is highly toxic and can decompose explosively. It is therefore desirable to be able to theoretically estimate any valuable results of certain experiments in advance in order to carry out experimental studies only for the most suitable molecular systems. We report the effect of hydrogen bonding on NMR properties of 15N≡13CH···X and 13C≡15NH···X hydrogen bonding complexes in solution, where X = 19F, 15N, and O=31P, calculated at the ωB97XD/def2tzvp and the polarizable continuum model (PCM) approximations. In many cases, the isotropic 13C and 15N chemical shieldings of the cyanide anion are not the most informative NMR properties of such complexes. Instead, the anisotropy of these chemical shieldings and the values of scalar coupling constants, including those across hydrogen bonds, can be used to characterize the geometry of such complexes in solids and solutions. 1J(15N13C) strongly correlates with the length of the N≡C bond.

scholarly journals “Ensemble” iterative relaxation matrix approach: A new NMR refinement protocol applied to the solution structure of crambin

1993 ◽  
Vol 15 (4) ◽  
pp. 385-400 ◽  
Author(s):  
Alexandre M. J. J. Bonvin ◽  
J. Antoon C. Rullmann ◽  
Rolf M. J. N. Lamerichs ◽  
Rolf Boelens ◽  
Robert Kaptein
Keyword(s):  
Solution Structure ◽  
Matrix Approach ◽  
Relaxation Matrix

scholarly journals THE CASE OF ASYMPTOTIC SUPERSYMMETRY

2013 ◽  
Vol 28 (14) ◽  
pp. 1350053 ◽  
Author(s):  
BRUCE L. SÁNCHEZ-VEGA ◽  
ILYA L. SHAPIRO
Keyword(s):  
Fixed Point ◽  
Renormalization Group ◽  
Gauge Coupling ◽  
High Energy ◽  
Systematic Investigation ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Asymptotic State ◽  
Stable Fixed Point ◽  
Scalar Couplings

We start systematic investigation for the possibility to have supersymmetry (SUSY) as an asymptotic state of the gauge theory in the high energy (UV) limit, due to the renormalization group running of coupling constants of the theory. The answer on whether this situation takes place or not, can be resolved by dealing with the running of the ratios between Yukawa and scalar couplings to the gauge coupling. The behavior of these ratios does not depend too much on whether gauge coupling is asymptotically free (AF) or not. It can be shown that the UV stable fixed point for the Yukawa coupling is not supersymmetric. Taking this into account, one can break down SUSY only in the scalar coupling sector. We consider two simplest examples of such breaking, namely N = 1 supersymmetric QED and QCD. In one of the cases one can construct an example of SUSY being restored in the UV regime.

Carbon magnetic resonance studies of some phenyl, furyl and thienyl organometallics. Some comments on carbon-metal scalar coupling

1974 ◽  
Vol 27 (2) ◽  
pp. 417 ◽  
Author(s):  
D Doddrell ◽  
KG Lewis ◽  
CE Mulquiney ◽  
W Adcock ◽  
W Kitching ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Coupling Constant ◽  
Aryl Substituent ◽  
Magnetic Resonance Studies ◽  
Thienyl Group ◽  
13C Chemical Shift

13C chemical shift variations within a series of phenyl, furyl and thienyl Group IVB organometallics appear to be best understood in terms of the usual alkyl and aryl substituent effects on 13C chemical shifts and not variations in dπ ?pπ metal-aryl interactions. Large changes in 13C-metal scalar coupling constants have been observed suggesting that other factors besides the s-character of the carbon-metal bond is responsible in determining the coupling constant.

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