Steric Bulk Controls Δ/Λ Handedness Enabling Stereodivergent Self-Assembly of Fe ^II ₂ L ₃ Cages

Developing a stereodivergent approach to access chiral metal-organic cages is an appealing yet challenging goal in the field of supramolecular chemistry. In this work, we report a stereodivergent method for constructing chiral cages via subcomponent self-assembly of a chiral diamine, 3-substituted 2-formylpyridines, and iron(II) ions, yielding structurally well-defined architectures. Remarkably, simply altering the steric properties of the subcomponents allows for selective control of the handedness at the metal vertices, thereby enabling the stereodivergent synthesis of chiral cages. Systematic modulation of the 2-formylpyridine substituents revealed a linear correlation between the molecular volume and diastereomeric excess, providing a predictable means of achieving stereoselective assembly. Furthermore, gas sorption studies revealed distinct N₂ uptake behaviors between the two diastereomers, with the Δ-isomer exhibiting significantly enhanced CO₂ selectivity. This work establishes a sterically governed strategy for tuning both the chirality and functional properties of metal-organic cages.