Intermolecular multiple-quantum coherences between spin 1/2 and quadrupolar nuclei in liquid nuclear magnetic resonance

An NMR pulse sequence was used to study the signal features from intermolecular multiple-quantum coherences between spin 1/2 and quadrupolar nuclei in solution NMR for the first time. General theoretical expressions were derived from the raising and lowering operator formalism. Theoretical predictions for the relative signal intensities and the optimal pulse flip angles are in excellent agreement with experimental results. Both the magic angle gradient and 2D experiments validate that the signals are indeed from intermolecular heteronuclear multiple-quantum coherences.