Luminescent anticancer ruthenium(ii)-p-cymene complexes of extended imidazophenanthroline ligands: synthesis, structure, reactivity, biomolecular interactions and live cell imaging.

Of late, cancer has become a terrible disease affecting people throughout the world. Keeping this in mind, we tried to design drugs that are more lipophilic, target-specific, water-soluble, cytoselective and fluorescent. In this regard, we reported novel ruthenium(ii)-p-cymene imidazophenanthroline scaffolds as effective DNA targeting agents. The planarity of imidazophenanthroline ligands caused the Ru(ii) complex to be a good intercalator. An extended π-electronic conjugation was introduced in the imidazophenanthroline moieties through the Suzuki and Sonogashira coupling reactions. Here, we synthesized nine Ru(ii) complexes (16a-b, 17a-d, and 19a-c). Among these, [(η-p-cymene)RuCl(K-N,N-2-(4'-methyl-[1,1'-BIphenyl]-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline)]·PF (16b) exhibited the best potency and selectivity with excellent cellular uptake; [(η-p-cymene)RuCl(K-N,N-2-(4-(phenylethynyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline)]·PF (17a) acted as a cytoselective probe for live cell imaging.