A Diverse Array of Large Capsules Transform in Response to Stimuli

The allosteric regulationof biomolecules, such as enzymes, enablesthem to adapt and alter their conformation to fit specific substrates,expressing different functionalities in response to stimuli. Differentstimuli can also trigger synthetic coordination cages to change theirshape, size, and nuclearity by reconfiguring the dynamic metal-ligandbonds that hold them together. Here we demonstrate an abiologicalsystem consisting of different organic subcomponents and Zn-II metal ions, which can respond to simple stimuli in complex ways.A Zn-II L-20(12) dodecahedron transformsto give a larger Zn-II L-30(12) icosidodecahedronthrough subcomponent exchange, as an aldehyde that forms bidentateligands is displaced in favor of one that forms tridentate ligandstogether with a penta-amine subcomponent. In the presence of a chiraltemplate guest, the same system that produced the icosidodecahedroninstead gives a Zn-II L-15(6) truncatedrhombohedral architecture through enantioselective self-assembly.Under specific crystallization conditions, a guest induces a furtherreconfiguration of either the Zn-II L-30(12) or Zn-II L-15(6) cages to yield an unprecedentedZn(II) L-20(8) pseudo-truncated octahedralstructure. The transformation network of these cages shows how largesynthetic hosts can undergo structural adaptation through the applicationof chemical stimuli, opening pathways to broader applications.