Recent advances of the cyclometalated iridium(III) complexes for electrochemiluminescence sensing

Cyclometalated iridium(III) complexes have attracted much attention in electrochemiluminescence (ECL) assay in recent years due to their significant photophysical and electrochemical properties. The cyclometalated iridium(III) complexes, the iridium(III) metal center often as signaling unit, are usually designed with functional groups for specific target recognition owing to their flexible regulation of properties, which facilitates their broad application in chemical sensing, compared to the most investigated ECL reagent Ru(bpy)₃²⁺. Here, we pay much attention to the developments of the cyclometalated iridium(III) complexes as signal emitter for ECL sensing, briefly introduce the synthesis, type and ECL mechanism of the cyclometalated iridium(III) complexes, and emphatically describe the advances of ECL chemical sensing and biosensing based on the cyclometalated iridium(III) complexes, and highlight the strategies on the improvement of the cyclometalated iridium(III) complexes, including water solubility, ECL behaviour and wavelength tunability. The challenges and future perspectives of the cyclometalated iridium(III) complexes-based ECL method are also discussed.