Improved one-dimensional NMR detection of heteronuclear multiple quantum coherence involving the insensitive nucleus Se-77 as demonstrated by the compound C28H28O4Se4W2

When insensitive spins are detected by one-dimensional (1D) heteronuclear m ultiple quantum coherence (HMQC) spectroscopy, chemical shift modulation ca n easily reduce the signal intensity, leading to a poor signal-to-noise rat io (S/N) or sometimes vanishing signals. In this paper it is suggested that the 1D HMQC pulse sequence be modified by inserting a refocusing pi pulse in the multiple quantum evolution period. In this way optimal conditions fo r a good S/N can be easily achieved. The improved method is demonstrated by H-1/{Se-77} indirect detection using a newly synthesized compound C28H28O4 Se4W2 that contains the structure of W-2-Se-CH2C6H5.