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(m-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.

Supramolecular copolymers with complex architectures and emergent functions constitute a class of challenging but enticing synthetic targets in polymer science. Individual building blocks can be tailored to endow a resulting supramolecular copolymer with increased structural and functional complexity. Herein, we describe the construction of a linear supramolecular copolymer comprising mechanically interlocked segments with hydrogen-bonding metallorhomboidal units. Specifically, a hierarchical supramolecular polymerization of a crown ether-based [2]rotaxane and a discrete organoplatinum(II) metallacycle driven by 2-ureido-4-pyrimidinone (UPy) quadruple hydrogen bonding provides the impetus for its formation. This system demonstrates enhanced structural complexity accessed by the unification of orthogonal noncovalent interactions: metal coordination, host–guest chemistry, and multiple hydrogen bonding interfaces.