Cascading transformations within a dynamic self-assembled system.

Molecular subcomponents such as phosphate groups are often passed between biomolecules during complex signalling cascades, the flow of which define the motion of the machinery of life. Here, we show how an abiological system consisting of organic subcomponents knitted together by metal-ion coordination can respond to simple signals in complex ways. A Cu(I)(3) helicate transformed into its Zn(II)(2)Cu(I) analogue following the addition of zinc(II), and the ejected copper(I) went on to induce the self-assembly of a Cu(I)(2) helicate from other free subcomponents present in solution. The addition of an additional subcomponent, 8-aminoquinoline, resulted in the formation of a third, more stable Cu(I)(3) helicate, requiring the destruction of both the Zn(II)(2)Cu(I) and Cu(I)(2) helicates to scavenge sufficient Cu(I) for the new structure. This system thus demonstrates two examples in which the application of one signal provokes two distinct responses involving the creation or destruction of complex assemblies as the system seeks thermodynamic equilibrium following perturbation.