Two new phosphorescent Ir(III) complexes as efficient selective sensors for the Cu2+ ion

Two new cationic iridium(III) complexes were successfully synthesized as highly sensitive and selective phosphorescent sensors for detection of Cu2+ in MeOH/H2O (1:1) solution and in living cells. These cationic Ir(III) complexes were prepared by reactions of two different Ir(III) chloro-bridged dimers with 2,2'-dipyridine tethered DPA (di(2-picolyl)amine) moiety as the ancillary ligand. These phosphorescent sensors displayed significant reversible phosphorescence quenching upon binding to Cu2+ ions with a 10 ppb detection limit. They had strong binding ability with Cu2+ ions and the binding ratios were approximately 1:1, and also exhibited good cell permeability and good imaging characteristics in detecting Cu2+ ions in living cells. It is worth mentioning that one of the phosphorescent sensors is almost nontoxic to Hela cells, indicating that it greatly increases the possibility of application in biochemistry.