High-resolution NMR spectroscopy in inhomogeneous fields via heteronuclear intermolecular multiple-quantum coherences

A heteronuclear CRAZED pulse sequence was utilized to obtain high-resolution NMR spectra via heteronuclear intermolecular zero-quantum coherences (iZQCs) or intermolecular double-quantum coherences (iDQCs) in inhomogeneous fields. It overcomes the difficulty of selective excitation in homonuclear CRAZED experiments when the chemical shifts of solvent and solute are close to each other. In the 1D spectrum extracted from the 2D data, chemical shifts, coupling constants, multiplet patterns, and relative peak areas are almost independent of the magnetic field inhomogeneity. Theoretical predictions were verified by experimental observations.