“…Recently, cyclometalated transition-metal complexes, particularly Pt(II) and Ir(III), have gained widespread attention due to their impressive luminescent properties and for their performance as a highly effective class of singlet oxygen photosensitizers. − Even though the success of cisplatin as an anticancer agent has ignited a pursuit for the development of several inorganic anticancer drugs, they generally induce cell death via the oxygen-independent type III pathway and are referred as photoactivated chemotherapeutic (PACT) agents rather than as PDT agents. ,, Despite numerous reported examples of Pt(II) complexes as efficient singlet oxygen sensitizers, only a few platinum complexes have demonstrated photosensitizing effects via a type I or type II mechanism . Subsequently, it was found that iridium(III) complexes act as efficient photosensitizers through a type I or type II mechanism and are suitable for live-cell imaging-guided PDT applications. , In addition, iridium complexes show excellent photophysical and photochemical properties, such as a large Stokes shift, ease in color tuning, high triplet and singlet oxygen quantum yield, long luminescence lifetimes, and high chemical and photochemical stabilities. , …”