Manipulation of Charged Porous Cages as Tunable Platforms for Strong Gas Adsorption

Metal–organic frameworks (MOFs) have long been explored for their tunable structures and applications in gas separation and catalysis, yet systems capable of engaging in metal-to-ligand π-backbonding remain scarce. Expanding beyond MOFs, our study leverages porous coordination cages (PCCs) as modular building blocks to construct highly tunable porous salts. By incorporating coordinatively unsaturated, π-basic ruthenium sites within charged PCCs, we achieve selective and reversible carbon monoxide chemisorption, a property rarely observed in hybrid porous materials. We further demonstrate that nonporous molecular ruthenium complexes can be incorporated as charge-balancing counterions, yielding materials with tailored porosities and adsorption properties. These findings introduce a strategy for designing porous salts that integrate molecular reactivity with tunable porosity, offering promising avenues for next-generation separations, sensing, and catalysis. Our approach bridges molecular design principles with material functionality, expanding the toolkit for designing adaptive porous materials beyond traditional MOFs.