Recent progress in nuclear magnetic resonance strategies for time-resolved atomic-level investigation of crystallization from solution

Crystallization underpins essential processes in our everyday life, creating exceptional materials. Yet, fundamental understanding of the mechanisms underlying crystallization processes is still lacking because of the scarcity of experimental approaches allowing atomic-level investigation of the sequence of intermediate phases formed during crystallization as a function of time.We review recent progress of Nuclear Magnetic Resonance (NMR) in tackling this challenge across the last four years. New in-situ and ex-situ strategies are discussed, in which cryogenic conditions are combined with dynamic nuclear polarization (DNP) NMR to monitor crystallization. Under these conditions, both the temporal and structural resolution of the analysis increase, enabling the detection of – previously elusive – transient forms. We conclude with suggestions of future directions that could extend the capabilities of NMR even further, bringing key mechanistic details of crystallization process that could expand our fundamental understanding of crystallization and improve control over crystallization outcome.