Dynamic Nuclear Polarization with Vanadium(IV) Metal Centers

Dynamic nuclear polarization (DNP) harnesses the large polarization of electron spins to dramatically increase nuclear magnetic resonance (NMR) sensitivity. This study expands the scope of DNP beyond its traditional focus on hyperpolarizing the solvent network using exogenous polarizing agents (PAs). We introduce H-1 DNP with endogenous V4+ centers positioned in a set of vanadyl complexes with tunable V4+-H-1 distances. We traced the polarization transfer from V4+ to H-1 spins, specifically differentiating between direct V4+-(1)Hs polarization transfer and the H-1 spin-diffusion-mediated bulk solvent H-1 polarization buildup and illuminated the effect of the V4+-H-1 distance on these processes. These results deepen our understanding of polarization pathways and expand the catalog of PAs to broad-line transition metals. This study establishes crucial first steps toward employing strategically positioned endogenous paramagnetic metal centers for DNP and the conceptual framework of hyperfine DNP spectroscopy that merges both spatial and chemical diagnosis of target nuclear spins.

Automated summary

This study extends the application of dynamic nuclear polarization technology by introducing endogenous metal centers for nuclear magnetic resonance enhancement. By tracing polarization transfer, the research deepens understanding of polarization pathways and expands the catalog of polarizing agents.