First Examples of Luminescent Cyclometalated Iridium(III) Complexes as Labeling Reagents for Biological Substrates

Abstract

The syntheses, and photophysical and electrochemical properties of the three 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 isothiocyanate and iodoacetamide groups can react with the primary amine and sulfhydryl groups of biomolecules, respectively, complexes 1 and 2 have been used to label amine- or sulfhydryl-modified oligonucleotides, and human serum albumin, to give luminescent bioconjugates.