Ratiometric Iridium(III) Complex-Based Phosphorescent Chemodosimeter for Hg2+ Applicable in Time-Resolved Luminescence Assay and Live Cell Imaging

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.