No abstract

A highly selective and sensitive ratiometric and "turn-on" fluorescent probe for Fe(3+), 2-(1-pyrenyl) benzimidazole (L), was synthesized by a one-step process. In emission spectra, the relative intensity ratio of excimer to monomer fluorescence (IE450/IM387) of L increased 510-fold upon the addition of 30 equiv. of Fe(3+) with a detection limit of 0.2 μM (11.2 ppb) in aqueous solution. Meanwhile, the fluorescence excitation spectra of L showed a fluorescent "turn-on" probe for Fe(3+) with 30-fold enhancement in excitation band intensity of excimer.

Two probes ( and ) bearing two dansyl fluorophores were synthesized and applied to the detection of mercury(ii) ions in aqueous solution. These probes exhibited a selective response to Hg(2+) in a buffered solution, with high sensitivity and a unique fluorescence response signal which displayed a blue-shift effect in the fluorescence emission peak. The Hg(2+) recognition mechanisms of the probes were determined by NMR spectroscopy, ESI-MS and UV-vis spectroscopy. The results showed that probe and mercury(ii) ions formed an unusual 2:2 stoichiometric ratio complex, while probe and Hg(2+) formed a multidentate complex with a stoichiometric ratio of 2:1.