Chemoresponsive Supramolecular Polypseudorotaxanes with Infinite Switching Capability.

Chemoresponsive supramolecular systems with infinite switching capability are important for applications in recycled materials and intelligent devices. To attain this objective, here a chemoresponsive polypseudorotaxane is reported on the basis of a bis(p-phenylene)-34-crown-10 macrocycle (H) and a cyano-substituted viologen guest (G). H and G form a [2]pseudorotaxane (H⊃G) both in solution and in the solid state. Upon addition of AgSF6 , a polypseudorotaxane (denoted as [H⋅G⋅Ag]n ) forms as synergistically driven by host-guest complexation and metal-coordination interactions. [H⋅G⋅Ag]n depolymerizes into a [3]pseudorotaxane (denoted as H2 ⋅G⋅Ag2 ⋅acetone2 ) upon addition of H and AgSF6 , while it reforms with successive addition of G. The transformations between [H⋅G⋅Ag]n and H2 ⋅G⋅Ag2 ⋅acetone2 can be switched for infinite cycles, superior to the conventional chemoresponsive supramolecular polymeric systems with limited switching capability.