HyperBIRD: A Sensitivity-Enhanced Approach to Collecting Homonuclear-Decoupled Proton NMR Spectra†

Samples prepared following dissolution dynamic nuclear polarization (DNP) enable the detection of NMR spectra from low-γ nuclei with outstanding sensitivity, yet have limited use for the enhancement of abundant species like 1H nuclei. Small- and intermediate-sized molecules, however, show strong heteronuclear cross-relaxation effects: spontaneous processes with an inherent isotopic selectivity, whereby only the 13C-bonded protons receive a polarization enhancement. These effects are here combined with a recently developed method that delivers homonuclear-decoupled 1H spectra in natural abundance samples based on heteronuclear couplings to these same, 13C-bonded nuclei. This results in the HyperBIRD methodology; a single-shot combination of these two effects that can simultaneously simplify and resolve complex, congested 1H NMR spectra with many overlapping spin multiplets, while achieving 50–100 times sensitivity enhancements over conventional thermal counterparts.