Triphenylamine-based conjugated polymer/I− complex as turn-on optical probe for mercury(II) ion

A kind of triphenylamine-based conjugated polymer with simple structure, poly(9,9-dioctyl)-2,7-fluorene-co-N-4-phenylethenyl-4,4′-triphenylamine (PFT-PE), was successfully synthesized via Suzuki coupling reaction. Chemical structure of PFT-PE was verified by NMR and FT-IR analyses. PFT-PE possesses high fluorescence quantum efficiency in THF solution (~0.90), and its fluorescence was efficiently quenched by the introduction of I−, accompanied by the change of its apparent color from colorless to light yellow. Specificity for the detection of I− of PFT-PE was verified by anti-interference experiments toward other common anionic ions, and the detection limit reaches ~2.9 × 10−7 M (according to 3σ rule). Interestingly, thanks to the high association constant and matching ratio between I− and Hg2+, fluorescence of PFT-PE/I− complex recovered quickly with the presence of Hg2+. Most of background cationic ions brought slight interference to the detection of Hg2+ except for Ag+ and Cu2+, and their interference can be excluded readily by additional UV–vis analysis. Detection limit of ~2.4 × 10−7 M for Hg2+ can be obtained by PFT-PE/I−, suggests that PFT-PE can act as dual-channel, high selective, immediacy and sensitive optical probe for I− and Hg2+.