Multi-stimuli-responsive supramolecular gel constructed by pillar[5]arene-based pseudorotaxanes for efficient detection and separation of multi-analytes in aqueous solution

Abstract

Here, a novel pseudorotaxanes-type crosslinker of a supramolecular polymer network (WP5-PN) has been constructed from a host water-soluble pillar[5]arene (WP5) and a guest naphthalene dimethylamine derivative (PN) via a stepwise process involving multiple non-covalent interactions. The obtained supramolecular polymers were able to transform into a supramolecular polymer gel (WP5-PN-G) and show AIE properties in DMSO–H₂O binary solution. Interestingly, due to the dynamic and reversible nature of non-covalent interactions, the resultant supramolecular polymer gels exhibited external stimuli-responsiveness to different parameters, such as temperature, acid–base, competitive guest and mechanical stress. Moreover, WP5-PN-G showed fluorescent response for Fe³⁺ and Cu²⁺, while its xerogel showed excellent recyclable separation properties for these metal ions with adsorption rates up to 98.07% and 95.38%, respectively. Moreover, by rational introduction of these metal ions into the WP5-PN-G, corresponding metal ion coordinated metallogels, such as WP5-PN-FeG and WP5-PN-CuG were obtained. These metallogels could selectively and sensitively sense F⁻ and CN⁻, respectively. The detection limits of these metallogels for F⁻ and CN⁻ were about 1 × 10⁻⁸ M. The WP5-PN-G has potential applications in multi-analytes detection and separation as well as fluorescent display materials.