Design and application of a water-soluble phosphorescent Ru(ii) complex as turn-on sensing material for Hg 2

A novel phosphorescent chemodosimeter material Ruphen-1 based on a Ru(ii) complex has been designed and developed by introducing Hg -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 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 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 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 in living cells with notable phosphorescence enhancement by confocal luminescence imaging.