Supramolecular Polymerization Controlled by Reversible Conformational Modulation.

We report a new method for fabricating supramolecular polymers with controlled structure and molecular weight through reversible conformational modulation. To this end, the crown-ether-based "taco complex" was introduced. We prepared a monomer containing a bis(-phenylene)-32-crown-10 in the core, which can supramolecularly polymerize efficiently in solution. When the conformation of the crown ether core was folded into a taco complex, the linear supramolecular polymerization could be significantly depressed, thus decreasing the molecular weight of the supramolecular polymer. In addition, extracting the depolymerizing agent with aqueous solution of cucurbit[7]uril could disassociate the taco complex and regenerate the supramolecular polymer with molecular weight as high as before. It is anticipated that this study can provide a facile and general methodology for controllable supramolecular polymerization.