Influence of paramagnetic shift reagents on the spin-lattice relaxation times of13C nuclei and the13C?1H spin-spin coupling constants

1984 ◽  
Vol 24 (6) ◽  
pp. 924-926
Author(s):  
V. N. Torocheshnikov ◽  
N. M. Sergeev
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Paramagnetic Shift ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Spin Coupling Constants ◽  
Shift Reagents ◽  
Spin Spin Coupling

A study of 14N relaxation and nitrogen–proton spin coupling in Watson–Crick base pair models through Fourier transform measurements on NH proton spin–lattice relaxation in the rotating frame

1979 ◽  
Vol 57 (9) ◽  
pp. 1075-1079 ◽  
Author(s):  
Michael E. Moseley ◽  
Peter Stilbs
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Lattice Relaxation ◽  
Indirect Measurements ◽  
Spin Lattice ◽  
Proton Coupling ◽  
Nuclear Spin Lattice Relaxation

Indirect measurements of nitrogen-14 nuclear spin-lattice relaxation times and direct proton coupling constants are presented together with carbon-13 T1 data for a series of alkyl-substituted nucleic acid bases and mixtures thereof in DMSO-d6. With the exception of the guanine NH nitrogen, which possibly experiences a decrease in the electric field gradient upon complexation with cytosine, no indications of significant changes in the electronic environment around the nitrogen nuclei were found for any combination of bases. Forsen–Hoffman spin saturation transfer experiments on the NH and NH2 protons are also presented.

A study of 14N relaxation and nitrogen–proton spin coupling in nucleoside, indole, and ε-caprolactam systems through Fourier transform measurements of NH proton spin–lattice relaxation in the rotating frame

1978 ◽  
Vol 56 (9) ◽  
pp. 1302-1305 ◽  
Author(s):  
Michael Eugene Moseley ◽  
Peter Stilbs
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Lattice Relaxation ◽  
Indole Derivatives ◽  
Spin Lattice ◽  
Proton Coupling ◽  
Nuclear Spin Lattice Relaxation

Measurements of nitrogen-14 nuclear spin–lattice relaxation times and direct proton coupling constants are presented for a series of nucleosides and nucleoside bases and indole derivatives in DMSO-d6 and for a series of ε-caprolactam concentrations in CDCl3. The data were obtained through NH proton T1ρ measurements, a potentially useful alternative to direct 14N and 15N nuclear magnetic resonance for the study of e.g. NH hydrogen bonding.

Scalar Second-Kind Relaxation of 27Al, 69Ga and 71Ga Nuclei in Aluminium and Gallium Complexes

1983 ◽  
Vol 38 (10) ◽  
pp. 1173-1181 ◽  
Author(s):  
V. P. Tarasov ◽  
V. I. Privalov ◽  
G. A. Kirakosyan ◽  
Yu. A. Buslaev
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Lattice Relaxation ◽  
Nuclear Spins ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Exchange Processes ◽  
Scalar Contribution

Abstract Spin-spin and spin-lattice relaxation times of nuclei 69,71Ga, 27Al, 14N in anions [MClnBr4-n]-and the solvate complexes [M(CH3CN)6]3+, produced from dissolution of MCl3 and MBr3 in the mixture CH3CN + CH3NO2 (M = Ga, Al), are measured in the temperature range from -40 up to + 70 °C. It is shown that nuclear spins of 69,71Ga, 27Al relax in the anionic and cationic complexes by means of the second-kind scalar and quadrupole relaxation mechanisms (due to the relaxation of the nuclei 35,37Cl, 79,81Br, 14N). The complexes [MClnBr4-n]-and [M(CH3CN)6]3+ in the investigated solutions are inert and do not undergo exchange processes in the NMR time scale. The scalar spin coupling constants in [M(CH3CN)6]3+ are determined from the scalar contribution to the relaxation rate of 69,71Ga, 27Al, and the measured relaxation time of 14N in the solvate complex; the results are J(69Ga-14N) = 59 ± 5 Hz, J(71Ga-14N) = 74 ± 6Hz, J(27Al-14N) = 22 ± 2Hz.

1H–1H internuclear distance measurements in carbohydrates: proton transient nuclear Overhauser enhancement and spin-lattice relaxation in (13C)- and (2H)-substituted compounds

1990 ◽  
Vol 68 (12) ◽  
pp. 2171-2182 ◽  
Author(s):  
Paul C. Kline ◽  
Anthony S. Serianni ◽  
Shaw-Guang Huang ◽  
Michael Hayes ◽  
Robert Barker
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Lattice Relaxation ◽  
Substitution Effects ◽  
Distance Measurements ◽  
Spin Lattice ◽  
Nuclear Overhauser Enhancement ◽  
Nuclear Overhauser

Proton transient nuclear Overhauser enhancement (TnOe) and spin-lattice relaxation times (T1) have been used to evaluate the conformations of several monosaccharides and disaccharides containing (13C) and (2H) substitution. Absolute 1H–1H internuclear distances were determined by TnOe and DESERT (deuterium substitution effects on relaxation times) experiments on conformationally rigid methyl β-D-galactopyranoside and α- and β-D-xyloses, respectively. The DESERT method was extended to examine O-glycoside conformation in two blood-group disaccharides that were prepared enzymically with (13C) and (or) (2H) substitution. Preferred disaccharide conformations deduced from these distance measurements are compared to those determined from 13C–13C and 13C–1H spin coupling constants, theoretical calculations, and crystallographic studies. Keywords: TnOe, DESERT, carbohydrate conformation.

13C and 2H spin–lattice relaxation in neopentane-d12

1978 ◽  
Vol 56 (19) ◽  
pp. 2576-2581 ◽  
Author(s):  
Brian A. Pettitt ◽  
Roderick E. Wasylishen ◽  
Ronald Y. Donc ◽  
T. Phil Pitner
Keyword(s):  
Melting Point ◽  
Variable Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Rotation ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Single Temperature ◽  
Momentum Correlation

The results of a variable temperature study of the 2H and 13C spin–lattice relaxation times in neopentane-d12 are reported. along with those for the 13C's in neopentane at a single temperature. Orientational and angular momentum correlation times derived from these T1's exhibit the following: (i) τ2 is continuous through the melting point with an activation energy of 0.98 kcal/mol, (ii) τJ is more or less constant at 0.33 ± 0.03 ps within 40 K of either side of the melting point, and (iii) they do not conform to the theoretical relationships of extended diffusion, Fokker–Planck, or Langevin theories. The spin–rotation coupling constants are calculated to be −0.69 kHz for neopentane and −0.52 kHz for neopentane-d12

The conformational equilibrium in [13C-1-methyl]-cis-1,4-dimethylcyclohexane

1980 ◽  
Vol 58 (23) ◽  
pp. 2709-2713 ◽  
Author(s):  
Harold Booth ◽  
Jeremy Ramsey Everett
Keyword(s):  
Conformational Equilibrium ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nuclear Overhauser ◽  
In Cis ◽  
C Nmr

The conformational equilibrium in [13C-1-methyl]-cis-1,4-dimethylcyclohexane has been assessed by (a) direct integration of signals due to equatorial and axial methyl carbons in the 13C nmr spectrum at 172 K and (b) by measurement of the 13C chemical shifts of C-1 and C-4 in the spectrum at 300 K. It is concluded that a 13C isotope effect on the position of the degenerate equilibrium in cis-1,4-dimethylcyclohexane is either nonexistent, or is too small to be detected by methods of analyses employed. The 13C nmr data incidental to the study (chemical shifts, coupling constants, spin–lattice relaxation times, nuclear Overhauser enhancements, and 1-bond isotope shifts) are recorded for the title compound and its trans-isomer.

Boron-11, boron-10, and nitrogen-14 NMR relaxation rates and quadrupole coupling constants in BH3NH3

1992 ◽  
Vol 70 (9) ◽  
pp. 2420-2423 ◽  
Author(s):  
Glenn H. Penner ◽  
Stephen I. Daleman ◽  
Angela R. Custodio
Keyword(s):  
Relaxation Times ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Orbital Theory ◽  
Spin Lattice ◽  
Quadrupolar Coupling ◽  
Field Gradients

The 11B, 10B, and 14N spin–lattice relaxation times (T1) for aqueous solutions of BH3NH3 were measured by NMR spectroscopy. The results of this investigation are consistent with the nuclear quadrupolar coupling constants reported in previous nuclear quadrupolar resonance and microwave studies. The activation energy associated with rotational reorientation of BH3NH3 in aqueous solution is 11.7 ± 0.6 kJ/mol. Electric field gradients were calculated at various levels of abinitio molecular orbital theory, in order to obtain theoretical 14N and 11B quadrupolar coupling constants. At the highest level of calculation (CI(SD)/6-31G**//MP2/6-31G**), these are in agreement with recently reported microwave results but not with previously reported NQR experiments.

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