Chirality-Driven Self-Assembly of Discrete, Homochiral FeII2L3 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 (Fe2L3)-L-II cages via chirality-driven self-assembly. Specifically, the installation of chirality - at both the vertices and ligand backbones - allows the formation of discrete, homochiral (Fe2L3)-L-II 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 (Fe2L3)-L-II 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 (Fe2L3)-L-II cages formed in enantiomeric pairs.

Automated summary

Coordination chemistry is a powerful method for synthesizing supramolecular cages with specific applications. This study successfully synthesized discrete, homochiral (Fe2L3)-L-II cages through chirality-driven self-assembly. The size of these cages can be controlled by stereochemical manipulation of the iron(II) centers, and their formation requires chirality at both the vertices and ligand backbones. The smaller cages exhibit stereoselectivity with only chiral ligands, and their formation is driven by non-covalent interactions.