Chirality-Driven Self-Assembly of Discrete, Homochiral Fe^II₂L₃ Cages

Coordination chemistry is a powerful method to synthesize supramolecular cages with distinct features that suit specific applications. This work demonstrates the synthesis of discrete, homochiral Fe^II₂L₃ cages via chirality-driven self-assembly. Specifically, the installation of chirality – at both the vertices and ligand backbones – allows the formation of discrete, homochiral Fe^II₂L₃ cages of different sizes via stereochemical control of the iron(II) centers. We observed that larger cages require multiple chiral centra (chiral ligands and vertices). In contrast, the formation of smaller cages is stereoselective with solely chiral ligands. The latter cages can also be formed from two chiral subcomponents, but only when they have matching chirality. Single-crystal X-ray diffraction of these smaller Fe^II₂L₃ cages revealed several non-covalent interactions as a driving force for narcissistic chiral self-sorting. This expected behavior was confirmed utilizing the shorter ligands in racemic form, yielding discrete, homochiral Fe^II₂L₃ cages formed in enantiomeric pairs.