A bis-naphthalimide functionalized pillar[5]arene-based supramolecular π-gel acts as a multi-stimuli-responsive material

Abstract

In this work, a novel supramolecular π-gel has been constructed using a naphthalimide functionalized pillar[5]arene-based gelator (MP5). The gelator MP5 simultaneously contains a naphthalimide moiety as the π⋯π interaction site as well as a fluorophore. Interestingly, the MP5-based supramolecular π-gel (MP5-G) exhibits strong aggregation-induced emission (AIE). MP5-G exhibited good thermal-responsiveness, acid and base-responsiveness and cation and amino acid-responsiveness. Meanwhile, this supramolecular π-gel also shows selective fluorescence sensing for Fe³⁺via cation–π interactions with high selectivity and sensitivity, and the detection limit of MP5-G for Fe³⁺ is 6.06 × 10⁻⁸ M. Even more meaningfully, MP5-G could remove Fe³⁺ from water solution with excellent recyclability and ingestion capacity, and the Fe³⁺ removal rate can reach up to 99.8%. Furthermore, the Fe³⁺ coordinated supramolecular gel, MP5-FeG, shows selective fluorescence “turn-on” sensing for L-Cys. The detection limit of MP5-FeG for L-Cys is 1.0 × 10⁻⁸ M. Simultaneously, thin films based on these supramolecular gels were prepared, which were confirmed to be convenient test kits for detecting Fe³⁺ and L-Cys. In addition, these supramolecular π-gels could be used as sensitive ion sensors, sensitive logic gates and fluorescent display materials.