Ion Pair Recognition Based Supramolecular Polymer Showing Rapid and Reversible Sol–Gel Transition through van der Waals Interactions

Ion pair receptors have shown potential in controllable recognition of cations and anions simultaneously, which has made a vital contribution to various research fields. Herein, rationally designed ion pairs were integrated into a calix[4]pyrrole skeleton, resulting in the formation of an ion pair recognition based linear supramolecular polymer. The effect of simultaneous host–guest and cation−π interactions between carboxylate-functionalized calix[4]pyrrole and cetyltrimethylammonium was investigated by nuclear magnetic resonance spectroscopy, viscosity measurements, scanning electron microscopy, and differential scanning calorimetry. The resulting supramolecular polymer was found to show temperature-induced rapid and reversible sol–gel transition through van der Waals interactions of cetyl units.