Optically Enhanced Solid-State 1H NMR Spectroscopy

Low sensitivity is the primary limitation to extending nuclear magnetic resonance (NMR) techniques to more advanced chemical and structural studies. Thanks to Photochemically induced dynamic nuclear polarization (photo-CIDNP) of a donor–acceptor chromophore molecule, we report the first example of optically enhanced solid-state 1H NMR spectroscopy in the high-field regime. These findings enable a new strategy for hyperpolarized NMR beyond the current limits of conventional microwave-driven DNP.

Low sensitivity is the primary limitation to extending nuclear magnetic resonance (NMR) techniques to more advanced chemical and structural studies. Photochemically induced dynamic nuclear polarization (photo-CIDNP) is an NMR hyperpolarization technique where light is used to excite a suitable donor–acceptor system, creating a spin-correlated radical pair whose evolution drives nuclear hyperpolarization. Here, we report the first example of optically enhanced solid-state 1H NMR spectroscopy in the high-field regime. This is achieved via photo-CIDNP of a donor–chromophore–acceptor molecule in a frozen solution at 0.3 T and 85 K, where spontaneous spin diffusion among the abundant strongly coupled 1H nuclei relays polarization through the whole sample, yielding a 16-fold bulk 1H signal enhancement under continuous laser irradiation at 450 nm. These findings enable a new strategy for hyperpolarized NMR beyond the current limits of conventional microwave-driven DNP.