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 A2 L3 (A=anion, L=ligand) anionocage triggers the release and delivery of a TEA+ (tetraethylammonium) guest to another A2 L3 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.