Pulsed Field Gradient ‘Inverse’ HOESY Applied to the Isotope Pairs1H,31P and1H,7Li*

For many heteronuclei, inverse (1H detected) heteronuclear Overhauser effect spectroscopy (HOESY) should be superior in theory over heteronucleus detected HOESY. In practice, strong t1 noise artifacts completely cancel the benefits of inverse HOESY. However, pulsed field gradient (PFG)-enhanced inverse HOESY yields 2D spectra without any t1 noise, consisting only of genuine cross peaks. The applicability of the method is demonstrated for thymolphthalein monophosphate hydrate using 31P,1H PFG-HOESY and for n-butyllithium using 7Li,1H PFG-HOESY. In addition to the absence of t1 noise, the merit of PFG-inverse HOESY is improved digital resolution in the usually crowded 1H domain.