A Heterodinuclear Complex OsIr Exhibiting Near-Infrared Dual Luminescence Lights Up the Nucleoli of Living Cells

The heterodinuclear metal complex OsIr has been designed and synthesized. Upon irradiation with visible light, OsIr exhibits dual luminescence (534 and 721 nm) due to the coexistence of the iridium and osmium activating centers. The cellular uptake of OsIr examined by laser scanning confocal microscopy revealed an apparent nucleolar staining. The iridium moiety interacts with proteins and RNA to trigger a significant luminescence enhancement, whereas the osmium moiety displays a near-infrared luminescence; a ratiometric luminescence response between the two moieties was observed upon protein addition.