Single-Scan Heteronuclear ¹³C-¹⁵N J-Coupling NMR Observations Enhanced by Dissolution Dynamic Nuclear Polarization

Heteronuclear ¹³C-¹⁵N couplings were measured in single-scan nuclear magnetic resonance (NMR) experiments for a variety of nitrogen-containing chemical compounds with varied structural characteristics, by using a one-dimensional (1D) ¹³C-¹⁵N multiple-quantum (MQ)-filtered experiment. Sensitivity limitations of the MQ filtering were overcome by the combined use of ¹⁵N labeling and dissolution dynamic nuclear polarization (dDNP), performed at cryogenic conditions and followed by quick and optimized sample melting and transfer procedures. Coupling information could thus be obtained from nucleotide bases, amino acids, urea, and aliphatic and aromatic amides, including the measurement of relatively small J-couplings directly from the 1D filtered spectra. This experiment could pave the way for NMR-based analytical applications that investigate structural and stereochemical insights into nitrogen-containing compounds, including dipeptides and proteins, while relying on heteronuclear couplings and nuclear hyperpolarization.