First examples of luminescent cyclometalated iridium(III) complexes as labeling reagents for biological substrates

The syntheses, and photophysical and electrochemical properties of the thre e luminescent cyclometalated iridium (III) complexes [Ir(ppy)(2)(phen-NCS)] -(PF6) (1), [Ir(ppy)(2)(phen-NHCOCH2I)](PF6) (2), and [Ir-(ppy)(2)(phen-NH2 )](PF6) (3) (ppy(-) = 2-phenylpyridinate anion, phen-NCS = 5-isothiocyanato -1,10-phenanthroline, phen-NHCOCH2I = 5-(iodoacetamido)-1,10-phenanthroline , phen-NH2 = 5-amino-1,10-phenanthroline) are reported. Since the isothiocy anate and iodoacetamide groups can react with the primary amine and sulfhyd ryl groups of biomolecules, respectively, complexes 1 and 2 have been used to label amine- or sulfhydryl-modified oligonucleotides, and human serum al bumin, to give luminescent bioconjugates.