Nucleic acid intercalators and avidin probes derived from luminescent cyclometalated iridium(III)-dipyridoquinoxaline and -dipyridophenazine complexes

Abstract

Six luminescent cyclometalated iridium(III)-dipyridoquinoxaline and -dipyridophenazine complexes [Ir-(ppy)2(N-N)](PF6) (Hppy = 2-phenyl-pyridine; N-N = dipyrido[3,2-f:2′,3′-h]quinoxaline, dpq (1); 2-n-butylamido-dipyrido[3,2-f:2′,3′-h]quinoxaline, dpqa (2); 2-((2-biotinamido)ethyl)amidodi-pyrido[3,2-f:2′,3′-h]quinoxaline, dpqB (3); dipyrido[3,2-a:2′,3′-c]phenazine, dppz (4); benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine, dppn (5); 11-((2-biotin amido)ethyl)amidodipyrido[3,2-a:2′,3′-c]-phenazine, dppzB (6)) have been designed as luminescent intercalators for DNA and probes for avidin. The structure of complex 4 has been studied by X-ray crystallography. The photophysical and electrochemical properties of the complexes have also been investi gated. The binding of these complexes to double-stranded calf thymus DNA and synthetic double-stranded oligonucleotides poly(dA)·poly(dT) and poly-(dG)·poly(dC) has been investigated by spectroscopic titrations. The interactions between the two biotin-containing complexes and avidin have been studied by 4′-hydroxyazobenzene-2-carboxylic acid (HABA) assays and emission titrations. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.