Dynamic nuclear polarization (DNP) solid-state nuclear magnetic resonance (NMR) offers a recent approach to dramatically enhance NMR signals and has enabled detailed structural information to be obtained in a series of amorphous photocatalytic copolymers of alternating pyrene and benzene monomer units, the structures of which cannot be reliably established by other spectroscopic or analytical techniques. Large 13C cross-polarization (CP) magic angle spinning (MAS) signal enhancements were obtained at high magnetic fields (9.4-14.1 T) and low temperature (110-120 K), permitting the acquisition of a 13C INADEQUATE spectrum at natural abundance and facilitating complete spectral assignments, including when small amounts of specific monomers are present. The high 13C signal-to-noise ratios obtained are harnessed to record quantitative multiple contact CP NMR data, used to determine the polymers' composition. This correlates well with the putative pyrene:benzene stoichiometry from the monomer feed ratio, enabling their structures to be understood.
- aromatic compounds