A water-soluble and highly phosphorescent cyclometallated iridium complex with versatile sensing capability

Abstract A water-soluble and highly phosphorescent cyclometallated iridium complex [(pq) 2 Ir(bpy-COOK)] + Cl - (where pq=2-phenylquinoline, bpy-COOK= potassium 2,2′-bipyridine-4,4′-dicarboxylate) (Ir) has been synthesized and characterized. Its phosphorescence can be sensitively and selectively quenched by tryptophan through a photoinduced electron-transfer (PET) process. Furthermore, the phosphorescence of Ir is drastically increased upon binding with bovine serum albumin (BSA), and the enhanced signal is effectively quenched in the presence of Cu 2+ . Thus, Ir can be used as a multifunctional chemosensor for tryptophan, BSA, and Cu 2+ determination as well as for cell imaging.