Bambusuril Macrocycles as Mediators of Supramolecular Interactions: Application to the Europium Cage Helicate

Herein, it is shown how bambusurils can be used for tuning and/or characterizing supramolecular systems. Indeed, the addition of bambusurils as anion scavengers to metal‐mediated self‐assemblies allows manipulation of the subtle equilibria in the given system. This is demonstrated for the case of the tetranuclear europium helical cage, which is well suited to different applications. Among the reported results, experimental evidence is provided showing that perchlorate and triflate anions act as a molecular template for the cage assembly. The complexation of inorganic anions with neutral bambusurils resulted in bulky non‐coordinating counterions that may trigger the self‐assembly process or stimulate specific interactions between components. Moreover, bambusuril was able to selectively remove coordinating nitrates from the mixture with non‐coordinating anions, enabling the regeneration of the helical cage. A bambusuril macrocycle acts as an efficient and selective anion scavenger enabling the investigation of europium cage helicates. This study provides experimental evidence for the template effect of anions during the assembly of the supramolecular cage.