Dual-controlled guest release from coordination cages

Despite having significant applications in the construction of controlled delivery systems with high anti-interference capability, to our knowledge dual-controlled molecular release has not yet been achieved based on small molecular/supramolecular entities. Herein, we report a dual-controlled release system based on coordination cages, for which releasing the guest from the cage demands synchronously altering the coordinative metal cations and the solvent. The cages, Hg₅L₂ and Ag₅L₂, are constructed via coordination-driven self-assembly of a corannulene-based ligand. While Hg₅L₂ shows a solvent-independent guest encapsulation in all the studied solvents, Ag₅L₂ is able to encapsulate the guests in only some of the solvents, such as acetone-d₆, but will liberate the encapsulated guests in 1,1,2,2-tetrachloroethane-d₂. Hg₅L₂ and Ag₅L₂ are interconvertible. Thus, the release of guests from Hg₅L₂ in acetone-d₆ can be achieved, but requires two separate operations, including metal substitutions and a change of the solvent. Dual-controlled systems as such could be useful in complicated molecular release process to avoid those undesired stimulus-responses.