heteronuclear multiple quantum coherence HMQC NMR HMQC FIX:0000149 CHMO:0000603 A type of heteronuclear NMR spectroscopy where a second frequency dimension is employed to disperse the signals and reveal correlations between protons and the nuclei to which they are covalently bound. In HMQC the magnetisation of both nuclei is allowed to evolve over time. heteronuclear two-dimensional nuclear magnetic resonance spectroscopy