Surface Enhanced Nuclear Magnetic Resonance Spectroscopy at Solid–Liquid Interfaces Using Overhauser Dynamic Nuclear Polarization

While solid-liquid interfaces are ubiquitous, detecting the associated surface sites under ambient conditions remains a grand challenge. Here, we demonstrate an approach to efficiently enhance the NMR signals of solid surfaces at the solid-liquid interface at ambient temperature that is based on exchange mediated Overhauser effect dynamic nuclear polarization (OE-DNP). We use this approach to obtain DNP enhancements for the ³¹P signals of PPh₃ ligands interacting with Rh(I) surface sites, in prototypical silica-supported materials prepared via surface organometallic chemistry. Efficient enhancement (ε_i) is obtained under ambient conditions simultaneously at the surface (ε_surface = 20-30) and in solution (ε_solution up to 50), enabling detection of species both at the surface and in solution, opening the possibility to monitor surface and interfacial chemistry.