Photofunctional Cyclometalated Iridium(III) Polypyridine Complexes Bearing a Perfluorobiphenyl Moiety for Bioconjugation, Bioimaging, and Phototherapeutic Applications

Chemoselective reactions are useful for the covalent attachment of functional entities to biomolecules to create novel constructs for biological applications. In this work, we modified cyclometalated iridium(III) polypyridine complexes with a perfluorobiphenyl (PFBP) moiety to afford novel reagents for bioconjugation, bioimaging, and phototherapeutic applications. Reactions of the PFBP complexes with peptides containing an FCPF (pi-clamp) sequence via the selective cysteine conjugation yielded luminescent peptide conjugates that displayed rich photophysical and photochemical properties. Importantly, the conjugation of complexes to organelle-targeting peptides was found to modulate their intracellular localization behavior, which was further shown to be important to their photosensitization properties and photocytotoxicity.