A “Turn-on” fluorescent chemosensor with the aggregation-induced emission characteristic for high-selective detection of Hg²⁺

A hexaphenyl-1, 3-butadiene derivative containing methylpyridinium moiety, 4, 4'-((1E, 1'E)-(((1E, 3E)-1, 2, 3, 4-tetraphenylbuta-1, 3-diene-1, 4-diyl)bis(1, 4-phenylene))bis(ethene-1, 2-diyl))bis(N-methylpyridinium) iodide (HPB-PyM), was firstly synthesized through Heck reaction of HPB-Br with 4-vinylpyridine and subsequent methylation with iodomethane. As the precursors of HPB-PyM, HPB-Br and HPB-Py showed excellent aggregation-induced emission characteristic. In contrast, HPB-PyM exhibited orange emission (λ_em=605 nm) in the solid state with aggregation-caused quenching (ACQ) characteristic. Moreover, the fluorescence of HPB-PyM via AIE mechanism could be lightened and significantly enhanced by Hg²⁺ ions. As a “turn on” probe, HPB-PyM not only exhibited a rapid, sensitive, and selective response towards Hg²⁺ but also achieved linear and colorimetric detection for Hg²⁺ with a detection limit of 4.153 μmol/L.