Evolution-Inspired Crystal Solutions

On its face, crystallization feels like it shouldn’t work; how can a multicomponent solution partition into a pure solid and leave everything else in solution, and with only modest energy input? But this is where design of crystallization processes could be most exploited! There are countless difficult chemical separations where crystallization could enhance efficiency, but my group would initially focus on those with environmental impact: direct air capture of CO₂ (DAC) and removing fermentation products from broth. Designing a molecular system to distinguish these small constituents and then cooperatively change phase is analogous to proteins recognizing their ligand and then altering conformation. Looking to nature, we see that carbonic anhydrases have conserved arginine and aspartate residues in the carbonate binding pocket, as well as histidine and cysteine to coordinate the catalytic zinc. So far, the best crystallizing carbon capture molecules (molecules that crystallize from solution, pulling sorbed CO₂ with them) have guanidine moieties that form hydrogen bonds with carbonate, can we do better by looking at nature? Or rather than trying to replicate nature's carbon capture machinery, can we recreate the process that stumbled upon that machinery?