Correlated spectroscopy coupling constant measurement

Marion D, Wuthrich K (1983) Application of phase sensitive two-dimensional correlated spectroscopy (COSY) for measurement of IH-IH spin-spin coupling constants in proteins. Biochem Biophys Res Commun 113 967-974... 

Exchange correlation spectroscopy (E. COSY), a modified form of COSY, is useful for measuring coupling constants. The pulse sequence of the E. COSY experiment has a mixing pulse )3 of variable angle. A number of experiments with different values of /3 are recorded that eliminate the multiplet components of unconnected transitions and leave only the multiplet components for connected transitions. This simplified 2D plot can then be used to measure coupling constants. 

In addition to these limited procedures a number of experimental methods (vibrational spectroscopy, dipole moment measurements, electron diffraction, NMR, etc.) have been employed to determine the relative stabilities of these complexes.11,23 Intense effort has been directed towards establishing some kind of correlation between NMR parameters and stability of the borane complexes. The chemical shifts alone rarely show good correlation. However, complexation shifts (the chemical shift difference between the free and complexed borane or ligand) and various spin-spin coupling constants correlate better with calorimetric data, especially for ligands or boranes belonging to structurally similar series (Table 2).10,24... 

Undoubtedly the Chalk River ISOL will be used, as others are, in the identification and spectroscopy of exotic nuclei. The nuclear chart in figure 5 illustrates the scope for such studies. However, the extreme purity of isotopes separated by our ISOL has been essential in the past to precision studies of the weak interaction, in one case the lifetimes of superallowed 0+ 0+ transitions [K.OS83], in another 8-v-a triple correlation coefficients in the decay of 2( Na [CLI83] both yielded measurements of the weak vector coupling constant. These types of measurements will be extended to other nuclei, since they exploit the best qualities of the accelerator and separator. 

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