Construction of stimuli-responsive supramolecular gel: Via bispillar[5]arene-based multiple interactions

A linear supramolecular polymer has been constructed from host-guest recognition of two complementary homoditopic monomers, a novel bispillar[5]arene and a bipyridinium salt derivative. Furthermore, the linear supramolecular polymer could self-assemble to form a supramolecular gel at high concentration, which exhibited external stimuli-responsiveness. When the competitive guest adiponitrile was added to the viscous solution at high temperature, the obtained solution could not form a supramolecular gel on cooling. Moreover, this gel could effectively sense Fe³⁺ with specific selectivity. Simultaneously, a thin film based on the supramolecular gel was prepared, which was confirmed to be a convenient test kit for detecting iron ions.