Enhancement of the NMR spectra of insensitive nuclei using PENDANT with long-range coupling constants

Abstract

The recently reported NMR pulse sequence PENDANT, that enables the simultaneous detection of all insensitive nuclei (S), of a given type, in a compound and the enhancement of the signals arising from those nuclei coupled to sensitive nuclei (I), is developed further. The sequence has been modified to enable the detection of spin–spin coupled multiplets without phase distortions. Its normal form, for use with short range coupling constants, has been adapted to facilitate the S–N enhancement of insensitive nuclei through the use of long range coupling constants. The developments are illustrated by reference to {¹H}–¹³C and {¹H}–²⁹Si spectra.