Narcissistic Self-Sorting in Self-Assembled Cages of Rare Earth Metals and Rigid Ligands

Highly selective, narcissistic self‐sorting can be achieved in the formation of self‐assembled cages of rare earth metals with multianionic salicylhydrazone ligands. The assembly process is highly sensitive to the length of the ligand and the coordination geometry. Most surprisingly, high‐fidelity sorting is possible between ligands of identical coordination angle and geometry, differing only in a single functional group on the ligand core, which is not involved in the coordination. Supramolecular effects allow discrimination between pendant functions as similar as carbonyl or methylene groups in a complex assembly process. Equals among equals: The formation of self‐assembled cages of rare earth metals and ligands proceeds through highly selective, narcissistic self‐sorting. Pendant functionalities as similar as carbonyl and methylene groups are discriminated in this complex assembly process.