Measuring coupling constants spin decoupling

Full chemical-shift and coupling-constant data for OPF2H, SPF2H, and SePF2H have been obtained from and F n.m.r. measurements using heteronuclear spin-decoupling techniques. ... 

Molecules labeled with deuterium and/or tritium are useful for fundamental investigations in a variety of chemical fields, particularly spin decoupling in NMR,1 the measurement of coupling constants in ESR,2 mass spectrometry,3-4 and general reaction mechanism studies. Such tagged compounds are also valuable as tracers in biochemical and medical research. 

The derivative A of the effective field Iv Kv,) = ( y/2 7r) fi (r, ) is central to the theory of heteronuclear decoupling, where it represents the effective scaling factor of heteronuclear coupling constants (Waugh, 1982b). The parameter A is also a measure of the degree to which spins with similar chemical shifts are Hartmann-Hahn matched, because... 

Heteronuclear coupling constants (1,b7c,h) are most commonly measured from heteronuclear 2D experiments. The 3/c H couplings can be easily extracted from /-resolved spectra as well as from f or F2 proton coupled HSQC spectra. The undesired evolution of "/CH during q can be eliminated with use of an appropriate bilinear rotation decoupling (BIRD) pulse, such as BIRDd,x in. /-resolved spectroscopy35 and 111RD in Fi-coupled HSQC.36 Spin-state selective excitation techniques, S3E and S3CT37 38 (spin-state-selective coherence transfer), can also be used for the measurement of... 

In heteronuclear y-resolved spectra chemical shifts of an arbitrary nucleus X which couples with protons (this is mostly are presented on one axis and proton-X J couplings on the other. The information content is equivalent to that in a proton-coupled "C spectrum (Fig. 12) but without the severe overlap of multiplets which is usually encountered in the latter. In common with off-resonance proton decoupling, y-modulated spin echo, and DEPT experiments, it facilitates multiplicity determination. In addition, it enables proton-X coupling constants to be measured. 

N spectrum is observed without decoupling for an appropriate crosspolarization time T, the spin coupling constants can be directly measured provided that an additional tt/2 pulse is conveniently applied at the end of the cross-polarization sequence in order to remove the phase anomalies (C 25). 

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