Carbonic anhydrase mimics for enhanced CO₂ absorption in an amine-based capture solvent

Two new small-molecule enzyme mimics of carbonic anhydrase were prepared and characterized. These complexes contain the salen-like ligand bis(hydroxyphenyl)phenanthroline. This ligand is similar to the salen-type ligands previously incorporated into carbonic anhydrase mimics but contains no hydrolyzable imine groups and therefore serves as a promising ligand scaffold for the synthesis of a more robust CO₂ hydration catalyst. These homogeneous catalysts were investigated for CO₂ hydration in concentrated primary amine solutions through which a dilute CO₂ (14%) fluid stream was flowed and showed exceptional activity for increased CO₂ absorption rates.