Biomimetic Molecular Discrimination in a MOF Nanochannel: Enzyme-Mimetic Strategy for Full Exclusion of Mono- from Dibranched Alkanes

The separation of hexane isomers is crucial for producing high-octane gasoline but is challenged due to their similar properties. Herein, a biomimetic separation strategy was presented inspired by the molecular recognition mechanism of enzyme active sites to achieve hexane isomer separation. Through rational design of pore geometry and chemical environment, Ni-pca-pyz, with the precision of biological systems, was developed. The framework features optimized aperture size (∼5.2 Å) and tailored surface functionality, enabling perfect discrimination between mono- and dibranched isomers. This biomimetic design resulted in excellent separation performance, with breakthrough experiments directly producing high-purity dibranched isomers with research octane numbers (RON) above 90. Theoretical calculations confirmed that the exceptional separation performance stems from the synergy between steric exclusion and favorable host–guest interactions, effectively replicating the lock-and-key recognition mechanism observed in enzymatic systems. This work establishes a biomimetic paradigm for advanced, energy-efficient separation materials.