Abstract
Oxovanadium(IV) complexes [VO(Fc-tpy)(acac)](C104) (1), [VO(Fc-tpy)(nap-acac)](C104) (2), [VO(Fc-tpy)(py-acac)](C104) (3) and [VO(Ph-tpy)(py-acac)](C104) (4) of 4′-ferrocenyl-2,2′:6′,2″-terpyridine (Fc-tpy) and 4′-phenyl-2,2′:6′,2″-terpyridine (Ph-tpy) having monoanionic acetylacetonate (acac), naph-thylacetylacetonate (nap-acac) or pyre ny lace ty lace to nate (py-acac) ligand were prepared, characterized and their photocytotoxicity in visible light studied. The ferrocenyl complexes 1-3 showed an intense charge transfer band near 585 nm in DMFand displayed Fc’/Fc and V(1V)/V(111) redox couples near 0.66 V and -0.95 V vs. SCE in DMF-0.1 M TBAP. The complexes as avid binders to calf thymus DNA showed significant photocleavage of plasmid DNA in green light (568 nm) forming “OH radicals. The complexes that are photocytotoxic in HeLa and MCF-7 cancer cells in visible light (400 700 nm) with low dark toxicity remain nontoxic in normal fibroblast 3T3 cells. ICP-MS and fluorescence microscopic studies show significant cellular uptake of the complexes. Photo-irradiation of the complexes causes apoptotic cell death by ROS as evidenced from the DCFDA assay.