Strategic Applications of Luminescent Iridium(III) Complexes as Biomolecular Probes, Cellular Imaging Reagents, and Photodynamic Therapeutics

Since the early 2000s there has been an increasing interest in using luminescent iridium(III) polypyridine complexes as biomolecular probes. Recently, the cellular uptake properties of luminescent iridium(III) polypyridine complexes have been widely investigated, and many of these complexes have been strategically functionalized to serve as cellular imaging reagents. In this chapter, we summarize the design and properties of luminescent cyclometalated iridium(III) complexes that have been applied in different biological studies. Selected examples include complexes that have been used as general cellular staining reagents, hypoxia sensors, intracellular probes for ions and molecules, and organelle-targeting bioimaging reagents. Additionally, bioimaging materials constructed from polypeptides, polymers, and nanoparticles modified with these complexes are described, and their applications are discussed. Furthermore, the emerging utilization of luminescent cyclometalated iridium(III) complexes as photosensitizers in photodynamic therapy is also reviewed.