Tuning the amphiphilicity of terpyridine-based fluorescent probe in water: Assembly and disassembly-controlled H g2+ sensing, removal, and adsorption of H2S.

A water-soluble terpyridine-based cationic fluorescent probe (SP-TPy) was synthesized, which emerged with pH-dependent amphiphilicity, resulting in self-assembly and disassembly in aqueous media with the aggregation-induced emission (AIE) property. In neutral water (pH 7.4), a moderate sensing response to Hg2+ ions was given by the self-assembly of SP-TPy. However, in acidic aqueous media, the monomer of SP-TPy not only appeared to be highly selective and sensitive for Hg2+ ions, but also displayed highly efficient removal of Hg2+ ions from solution by rapid precipitation, which was attributed to the coordination-triggered reassembly of SP-TPy. The removal efficiency of SP-TPy for Hg2+ was found to be over 99%. Further study indicated that the precipitates were composed of various polyhedral porous frameworks, a property that was further used to adsorb H2S gas to form HgS complexes with higher uptake capacities. In addition, SP-TPy can be efficiently regenerated and recycled using a simple treatment with acidic water after adsorption of the H2S gas.