Switching between Stacked Toroids and Helical Supramolecular Polymers in Aqueous Nanotubules.

Although significant advances have been made in supramolecular tubules, reversible polymerization in the tubular walls while maintaining their intact structure remains a great challenge. Here, reversible helical supramolecular polymerization of stacked toroids is reported, while maintaining tubular structures in aqueous solution. At room temperature, the tubules consist of discrete toroid stackings with hydrophobic interior. Upon heating, the tubules based on toroid stackings undergo a reversible helical supramolecular polymerization to transform into helical tubules by interconnecting between spirally open toroids. The helical polymerization arises from a tilting transition of the closed toroids that transform into spirally open toroids driven by the thermal dehydration of a hydrophilic oligoether dendron surrounding the toroid frameworks.