Green, Efficient Detection and Removal of Hg 2+ by Water-Soluble Fluorescent Pillar[5]arene Supramolecular Self-Assembly.

Developing a water-soluble supramolecular system for the detection and removal of Hg 2+ is extremely needed but remains challenging. Herein, we reported the facile construction of a fluorescent supramolecular system ( H ⊃ G ) in 100% water through the self-assembly of carboxylatopillar[5]arene sodium salts ( H ) and diketopyrrolopyrrole-bridged bis(quaternary ammonium) guest ( G ) by host-guest interaction. With the addition of Hg 2+ , the fluorescence of H ⊃ G could be efficiently quenched. Since Hg 2+ showed synergistic interactions (coordination and Hg 2+ - cavity interactions with G and H , respectively), crosslinked networks of H ⊃ G @Hg 2+ were formed. A sensitive response to Hg 2+ with excellent selectivity and a low limit of detection (LOD) of 7.17 × 10 -7 M was obtained. Significantly, the quenching fluorescence of H ⊃ G @Hg 2+ can be recovered after a simple treatment with Na 2 S. The reusability of H ⊃ G for the detection of Hg 2+ ions was retained for four cycles, indicating the H ⊃ G could be efficiently used in a reversible manner. In addition, the H ⊃ G could efficiently detect Hg 2+ concentration in real samples (tap water and lake water). The developed supramolecular system in 100% water provides great potential in the treatment of Hg 2+ detection and removal for environmental sustainability.