7. Hyperpolarization of Nitrogen-15 Schiff Bases by Reversible Exchange Catalysis with para-Hydrogen
NMR with thermal polarization requires relatively concentrated samples, particularly for nuclei with low abundance and low gyromagnetic ratios, such as 15N. We expand the substrate scope of SABRE, a recently introduced hyperpolarization method, to allow access to 15N-enriched Schiff bases. These substrates show fractional 15N polarization levels of up to 2?% while having only minimal 1H enhancements.