Selective recognition of DNA defects by cyclometalated Ir(iii) complexes

Selective detection of DNA defects is an attractive approach for early detection of various tumors and diseases. Ru(ii), Rh(iii) and hybrid complexes have been reported in this regard. Here, we present three heteroleptic cyclometalated Ir(iii) complexes [Ir(phpy)2(imiphen)]+(Ir-1), [Ir(phpy)2(furphen)]+(Ir-2) and [Ir(phpy)2(faqphen)]+(Ir-3) where imiphen: 2-(1H-imidazol-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline; furphen: 2-(furan-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline and faqphen: 2-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione have been synthesized and characterized by analytical techniques. All three complexes recognize DNA defects with high selectivity as Ir-1 recognizes the abasic site opposite T and CA mismatch, Ir-2 recognizes Ab : G and Ir-3 recognizes the TT mismatch preferably. The results from this study further emphasize that the development of new luminescent probes requires fine-tuning of the ligand structure and the choice of the metal center to improve selectivity in recognition of DNA defects.