Near-Infrared emitting AIE multinuclear cationic Ir(III) complexes assembled nanoparticles for photodynamic therapy

Near infrared (NIR) emission and impressive singlet oxygen (1O2) generation ability are highly desirable but still difficult to realize simultaneously for aggregation-induced emission (AIE) photosensitizers (PSs). Herein, mono- and tri-nuclear NIR AIE cationic Ir(III) complexes and their corresponding self-assembled nanoparticles (NPs) without any surfactants or adjuvants were designed and synthesized by integrating of the rigid 1,3,5-triphenyl benzene as extended π-conjugation bridge. The pure NPs exhibit multiple merits of stronger NIR emission, higher 1O2 production capacity, better water solubility and negligible dark toxicity compared with the Ir(III) complexes. Notably, the AIE PS3 NPs possess bright NIR emission at 730 nm, suitable spherical size below 100 nm, favorable cellular uptake and superior phototoxicity (IC50 = 1.4 × 10−6 M). These are the first pure NIR emitting multinuclear Ir(III) complexes NPs obtained by self-assembly that exhibit excellent cell imaging and photodynamic therapy (PDT) performance.