Crown Ether Functionalized Potassium-Responsive Anionocages for Cascaded Guest Delivery

In many critical biological processes, host–guest chemistry of protein receptors is regulated by effector molecules to realize cascaded delivery of messenger molecules between different targets. Mimicking these natural processes with artificial receptors remains a challenge. Herein, we report a cascaded guest delivery between two anionocages (anion-coordination-driven cages), in a reversible manner, wherein binding of K⁺ ions by a crown ether functionalized, heteroleptic A₂L₃ (A=anion, L=ligand) anionocage triggers the release and delivery of a TEA⁺ (tetraethylammonium) guest to another A₂L₃ anionocage that is a weaker and less K⁺-sensitive receptor. Elimination of the K⁺ with [2,2,2]-cryptand enables recapture of the TEA⁺ by the crown ether functionalized anionocage and thus realizes a reversed guest delivery. Moreover, integrative self-sorting of anionocages is firstly reported, leading to heteroleptic cages with enhanced guest binding affinities.