A semi-rigid ligand could capture effectively Yb3+ ions to form a stable Yb3+ complex and provide a potential cavity to accommodate alkali metal ions. Only K+ ions could induce the Yb3+ complex to form a 1D coordination polymer and promote the in situ formation of an NIR membrane coated with bigger Yb3+ complex crystallites under mild conditions.

A novel phosphorescent chemodosimeter material Ruphen-1 based on a Ru(II) complex has been designed and developed by introducing Hg2+-promoted desulfurization and intramolecular cyclic guanylation of thiourea reaction into the luminophor. Ruphen-1 not only possessed a longer excitation wavelength, large Stokes shift and good water solubility, but also exhibited high selectivity and sensitivity only toward Hg2+ with a rapid turn-on phosphorescence response in an aqueous system over a wide range of pH (4.0–9.0). The detection limit for Hg2+ could reach 5.4 nM under physiological conditions (pH 7.2). The spectral response mechanism and structure changes of the chemodosimeter have been analyzed in detail through theoretical calculations and ESI-MS. Furthermore, by investigating the change in the phosphorescence lifetime of the chemodosimeter and employing the time-resolved emission spectra method, Ruphen-1 could effectively eliminate the interference of background fluorescence and further improve Hg2+ detection accuracy. Finally, Ruphen-1 showed low cytotoxicity toward living cells through the MTT assay, and exhibited potential applications in the detection and monitoring of the distribution of Hg2+ in living cells with notable phosphorescence enhancement by confocal luminescence imaging.

A novel Ru(II) complex-based phosphorescent probe Rubpy-1 was designed and synthesized conveniently by incorporating of chemodosimeter into the luminophor, which exhibits good water solubility, longer excitation wavelength, and rapid turn-on phosphorescent response only toward Hg2+ in aqueous system under physiological pH. The spectral response mechanism and Hg2+-promoted structure change of the chemodosimeter were analyzed in detail by theoretical calculations and electrospray ionization mass spectrometry. When time-resolved photoluminescence techniques were used, the Rubpy-1 could eliminate effectively the signal interference from the short-lived background fluorescence in complicated media, accompanied by the significant improvement of the signal-to-noise ratio and the accuracy of the detection. Furthermore, Rubpy-1 showed low cytotoxicity and excellent membrane permeability toward living cells, which was successfully applied to monitor intracellular Hg2+ effectively by confocal luminescence imaging.Keywords: cell imaging; chemodosimeter; Hg2+ recognition; phosphorescence; Ru(II) complex; TRES

A novel iridium(III) complex-based probe Ir4-1 has been designed and synthesized conveniently by incorporating the chemodosimeter into phosphorescent luminophor, which displayed ratiometric luminescence change from yellowish-green to reddish-yellow only toward Hg2+ ions in aqueous media via desulfurization and intramolecular cyclization with a broad pH range of 5–10. The phosphorescent chemodosimeter could eliminate effectively the signal interference from the short-lived fluorescent background, and the signal-to-noise ratio of the detection was improved distinctly by using time-resolved photoluminescence technique. Furthermore, the mechanism of phosphoresce change of the chemodosimeter was analyzed in detail by time-dependent density functional theory (TD-DFT) calculations, and the probe with long-wavelength emission could be applied to label cells and monitor intracellular Hg2+ effectively by luminescence ratio imaging.

A novel “turn-on” phosphorescent chemodosimeter based on a cyclometalated Ir(III) complex has been designed and synthesized, which displays high selectivity and sensitivity toward Hg2+ in aqueous media with a broad pH range of 4–10. Furthermore, by time-resolved photoluminescence techniques, some interferences from the short-lived background fluorescence can be eliminated effectively and the signal-to-noise ratio of the emission detection can be improved distinctly by using the chemodosimeter. Finally, the chemodosimeter can be used to monitor Hg2+ effectively in living cells by confocal luminescence imaging.

•A sensitive and selective Al3+ fluorescent chemosensor based on Schiff's base complex was developed.•The limit of detection for Al3+ is 0.17 μM in aqueous solution.•The chemosensor operated in aqueous solution.•The chemosensor can be applied in fluorescence microscopic imaging.A Schiff base-type fluorescent chemosensor, 2,2′-bipyridyl-3,3′-bis-(N,N′-disalicylidene)-formyhydrazone has been synthesized and characterized. Among the various metal ions, only Al3+ induces the fluorescence enhancement of the formylhydrazone and results in “OFF–ON” type sensing with excellent selectivity and high sensitivity in aqueous system. The lowest detection limit for Al3+ is 0.17 μM, which is much lower than the permissible concentration of Al3+ for drinking water in China. Also, the chemosensor can be applied to the monitoring of Al3+ ion in aqueous solution with a pH span 6–8. Furthermore, fluorescence microscopic imaging also indicates that the formylhydrazone chemosensor has the potential for the detection of Al3+ in the biological environment.

A semi-rigid ligand could capture effectively Yb3+ ions to form a stable Yb3+ complex and provide a potential cavity to accommodate alkali metal ions. Only K+ ions could induce the Yb3+ complex to form a 1D coordination polymer and promote the in situ formation of an NIR membrane coated with bigger Yb3+ complex crystallites under mild conditions.

A novel phosphorescent chemodosimeter material Ruphen-1 based on a Ru(II) complex has been designed and developed by introducing Hg2+-promoted desulfurization and intramolecular cyclic guanylation of thiourea reaction into the luminophor. Ruphen-1 not only possessed a longer excitation wavelength, large Stokes shift and good water solubility, but also exhibited high selectivity and sensitivity only toward Hg2+ with a rapid turn-on phosphorescence response in an aqueous system over a wide range of pH (4.0–9.0). The detection limit for Hg2+ could reach 5.4 nM under physiological conditions (pH 7.2). The spectral response mechanism and structure changes of the chemodosimeter have been analyzed in detail through theoretical calculations and ESI-MS. Furthermore, by investigating the change in the phosphorescence lifetime of the chemodosimeter and employing the time-resolved emission spectra method, Ruphen-1 could effectively eliminate the interference of background fluorescence and further improve Hg2+ detection accuracy. Finally, Ruphen-1 showed low cytotoxicity toward living cells through the MTT assay, and exhibited potential applications in the detection and monitoring of the distribution of Hg2+ in living cells with notable phosphorescence enhancement by confocal luminescence imaging.