Inverse detection and heteronuclear editing in 1H-15N correlation and 1H-1H double-quantum NMR spectroscopy in the solid state under fast MAS

Signal enhancement in heteronuclear correlation spectra as well as signal selection in H-1 experiments can be achieved through inverse, i.e., H-1, detection in the solid state under fast MAS conditions. Using recoupled polarization transfer (REPT), a heteronuclear H-1-N-15 single-quantum correlation (HSQC) experiment is presented whose symmetrical design allows the frequency dimensions to be easily interchanged. By observing the N-15 dimension indirectly and detecting on H-1, the sensitivity is experimentally found to be increased by factors between 5 and 10 relative to conventional N-15 detection. In addition, the inverse H-1-N-15 REPT-HSQC scheme can be readily used as a filter for the H-1 signal. As an example, we present the combination of such a heteronuclear filter with a subsequent H-1-H-1 DQ experiment, yielding two-dimensional N-15-edited H-1-H-1 DQ MAS spectra. In this way, specific selection or suppression of H-1 resonances is possible in solid-state MAS experiments, by use of which the resolution can be improved and information can be unravelled in H-1 spectra. (C) 2001 Academic Press.