An experimental evaluation of simplified procedures for determining the proton spin–lattice relaxation rates of natural products

1980 ◽  
Vol 58 (19) ◽  
pp. 2016-2023 ◽  
Author(s):  
Lawrence D. Colebrook ◽  
Laurance D. Hall
Keyword(s):  
Natural Products ◽  
Lattice Relaxation ◽  
Null Point ◽  
Proton Spin ◽  
Computational Method ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Spin Lattice ◽  
Simplified Procedures

A general discussion is given of the determination of the proton spin–lattice relaxation rates of natural products, with particular emphasis on use of the null-point method which, for the systems studied here, gives identical results with those obtained via the conventional (and relatively time consuming) computational method.

Proton Relaxation in Various Copper (II) Complexes and Determination of the Singlet-Triplet Separation

1980 ◽  
Vol 35 (1) ◽  
pp. 92-97 ◽  
Author(s):  
H. D. Jannek ◽  
W. Midler-Warmuth
Keyword(s):  
Copper Complexes ◽  
Lattice Relaxation ◽  
Magnetic Behaviour ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Temperature Dependent ◽  
Spin Lattice

Abstract Proton spin-lattice relaxation rates have been measured at 30 MHz as a function of temperature for a large number of dimeric copper complexes with the ligands 8-hydroxyquinoline, pyridine-N-oxide, methyl and dimethyl pyridine-N-oxide, and quinoline-N-oxide. Two carboxylates and adducts of several complexes with various solvents have also been studied. In contrast to some compounds with a normal magnetic behaviour, for most complexes a temperature dependent relaxation has been observed which agrees well with the concept of a weak antiferromagnetic interaction between the two Cu2+ ions. The singlet-triplet separations or exchange integrals have been determined.

scholarly journals NMR Spin-Lattice Relaxation and Tunnelling of Partially Deuterated Methyl Groups

1991 ◽  
Vol 46 (12) ◽  
pp. 1123-1130 ◽  
Author(s):  
H. Langen ◽  
W. Müller-Warmuth
Keyword(s):  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Spin States ◽  
Relaxation Rates ◽  
Spin Lattice ◽  
Conversion Rates ◽  
Temperature Relaxation ◽  
Field Cycling ◽  
Additional Influence

Abstract Proton spin lattice relaxation rates have been measured at 15 and 30 MHz and down to 5 K for the partially deuterated molecular crystals 4-F-toluene, 4-Cl-toluene, and 2,6-Cl2-toluene. The behaviour of these materials is governed by methyl group tunnelling. As compared with the undeuterated compounds, the low temperature relaxation is enhanced and the details depend on the removal of the symmetry coupling between rotator and spin states. The hindering barriers remain unchanged, the A to E conversion rates are faster, and relaxation is dominated by spectral density contributions J(2ωo) and J(2ω0). In one case an additional influence of level-crossing energy transfer on relaxation is observed. Field-cycling spectroscopy reveals steps rather than peaks if the proton spin Zeeman and tunnelling splittings match

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