Tracking mitochondrial dynamics during apoptosis with phosphorescent fluorinated iridium( III) complexes

Mitochondria are the control centers of apoptosis. To study mitochondrial dynamics during apoptosis, four phosphorescent fluorinated iridium(iii) complexes (Ir1-Ir4) were designed and synthesized. The complexes' emission maxima, phosphorescent quantum yields, and phosphorescent lifetimes are tuned by the degree of fluorination of the ligand. The complexes exhibit excellent photostability and low (photo)cytotoxicity in HeLa cells. As the complexes are cationic and lipophilic, they localize in mitochondria and enter cells through an energy-independent pathway. In comparison with commercially available mitochondrial trackers (e.g., MTR), Ir1-Ir4 exhibit high specificity to mitochondria even in fixed cells. Due to these outstanding properties, the complexes were successfully used to track mitochondrial dynamics during apoptosis.