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 Hg(2+) 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 Hg(2+) effectively in living cells by confocal luminescence imaging.

A graphene oxide–Fe3O4 nanocomposite against drug-resistant tumors by the combination of dual-drug chemotherapy and photothermal therapy with NIR.

A novel phosphorescent chemodosimeter material Ruphen-1 based on a Ru(II) complex has been designed and developed by introducing Hg 2+ -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 Hg 2+ 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 Hg 2+ 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 Hg 2+ 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 Hg 2+ in living cells with notable phosphorescence enhancement by confocal luminescence imaging.Scheme 1 (a) The Hg 2+ -induced reaction mechanism and the design principle; (b) structure change of chemodosimeter Ruphen-1.

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 Hg(2+) 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 Hg(2+) effectively by luminescence ratio imaging.

A new quinoline-based probe was designed that shows one-photon ratiometric and two-photon off-on changes upon detecting Cd(2+) . It exhibits fluorescence emission at 407 nm originating from quinoline groups in Tris-HCl (25 mM, pH 7.40), H2 O/EtOH (8:2, v/v). Coordination with Cd(2+) causes quenching of the emission at 407 nm and simultaneously yields a remarkable redshift of the emission maximum to 500 nm with an isoemissive point at 439 nm owing to an intramolecular charge-transfer mechanism. Thus, dual-emission ratiometric measurement with a large redshift (Δλ=93 nm) and significant changes in the ratio (F500 /F439 ) of the emission intensity (R/R0 up to 27) is established. Moreover, the sensor H2 L displays excellent selectivity response, high sensitive fluorescence enhancement, and strong binding ability to Cd(2+). Coordination properties of H2 L towards Cd(2+) were fully investigated by absorption/fluorescence spectroscopy, which indicated the formation of a 2:1 H2 L/Cd(2+) complex. All complexes were characterized by X-ray crystallography, and TD-DFT calculations were performed to understand the origin of optical selectivity shown by H2 L. Two-photon fluorescence microscopy experiments have demonstrated that H2 L could be used in live cells for the detection of Cd(2+).