SELECTIVE AND HETERONUCLEAR ROESY RELAXATION THEORY

The intramolecular dipole-dipole relaxation of weakly coupled AMX spin systems is analyzed for an expanded class of rotating-frame Overhauser enhancement spectroscopy experiments. In these experiments, the three nuclei may be locked in frames rotating at different frequencies, two nuclei may be locked at one frequency and the third at a second, or some of the nuclei may not be spin locked. The experiments can be carried out on chemically shifted homonuclear systems, heteronuclear systems, or combinations of both. These selectively locked (and heteronuclear) Overhauser enhancement spectroscopy experiments restrict the relaxation pathways available to the spin system in various, well-defined ways. This provides additional flexibility in tailoring experiments to (1) extract specific types of structural and other information contained in relaxation data and (2) preclude various indirect relaxation pathways that may complicate or compromise data analysis. © 1991.