title: Ternary iron(II) complex with an emissive imidazopyridine arm from Schiff base cyclizations and its oxidative DNA cleavage activity.
abstract: The ternary iron(II) complex [Fe(L')(L")](PF6)3(1) as a synthetic model for the bleomycins, where L' and L" are formed from metal-mediated cyclizations of N,N'-(2-hydroxypropane-1,3-diyl)bis(pyridine-2-aldimine)(L), is synthesized and structurally characterized by X-ray crystallography. In the six-coordinate iron(ii) complex, ligands L' and L" show tetradentate and bidentate chelating modes of bonding. Ligand L' is formed from an intramolecular attack of the alcoholic OH group of L to one imine moiety leading to the formation of a stereochemically constrained five-membered ring. Ligand L" which is formed from an intermolecular reaction involving one imine moiety of L and pyridine-2-carbaldehyde has an emissive cationic imidazopyridine pendant arm. The complex binds to double-stranded DNA in the minor groove giving a Kapp value of 4.1 x 10(5) M(-1) and displays oxidative cleavage of supercoiled DNA in the presence of H2O2 following a hydroxyl radical pathway. The complex also shows photo-induced DNA cleavage activity on UV light exposure involving formation of singlet oxygen as the reactive species.
authors.affiliation: Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Arindam
authors.initials: A
authors.lastname: Mukherjee
authors.forename: Shanta
authors.initials: S
authors.lastname: Dhar
authors.forename: Munirathinam
authors.initials: M
authors.lastname: Nethaji
authors.forename: Akhil R
authors.initials: AR
authors.lastname: Chakravarty
mesh_terms: D000818:Animals; D001761:Bleomycin / Q000737:chemistry; D002417:Cattle; D018360:Crystallography, X-Ray; D003500:Cyclization; D004247:DNA / Q000378:metabolism / Q000528:radiation effects; D004278:DNA, Superhelical / Q000737:chemistry / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D017665:Hydroxyl Radical; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry / Q000494:pharmacology*; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D011725:Pyridines / Q000737:chemistry / Q000494:pharmacology*; D012545:Schiff Bases / Q000737:chemistry*; D026082:Singlet Oxygen / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D004278:DNA, Superhelical; D008024:Ligands; D009942:Organometallic Compounds; D016877:Oxidants; D011725:Pyridines; D012545:Schiff Bases; D001761:Bleomycin; D026082:Singlet Oxygen; D017665:Hydroxyl Radical; D004247:DNA; C427203:calf thymus DNA; D006861:Hydrogen Peroxide; D007501:Iron; D010100:Oxygen