Donovan, K.J. and L. Frydman, HyperBIRD: A Sensitivity-Enhanced Approach to Collecting Homonuclear-Decoupled Proton NMR Spectra. Angew Chem Int Ed Engl, 2014: p. n/a-n/a.
Samples prepared following dissolution dynamic nuclear polarization (DNP) enable the detection of NMR spectra from low-gamma nuclei with outstanding sensitivity, yet have limited use for the enhancement of abundant species like 1 H nuclei. Small- and intermediate-sized molecules, however, show strong heteronuclear cross-relaxation effects: spontaneous processes with an inherent isotopic selectivity, whereby only the 13 C-bonded protons receive a polarization enhancement. These effects are here combined with a recently developed method that delivers homonuclear-decoupled 1 H spectra in natural abundance samples based on heteronuclear couplings to these same, 13 C-bonded nuclei. This results in the HyperBIRD methodology; a single-shot combination of these two effects that can simultaneously simplify and resolve complex, congested 1 H NMR spectra with many overlapping spin multiplets, while achieving 50-100 times sensitivity enhancements over conventional thermal counterparts.