Mukherjee, A.; Dhar, S.; Nethaji, M.; Chakravarty, A. R. Ternary iron(II) complex with an emissive imidazopyridine arm from Schiff base cyclizations and its oxidative DNA cleavage activity.
Dalton Transactions 2005, 349-353.
Abstract
The ternary Fe(II) complex [Fe(L')(L'')](PF6)3 (1) as a synthetic model for the bleomycins, where L' (I) and HL'' (II) are formed from metal-mediated cyclizations of N,N'-(2-hydroxypropane-1,3-diyl)bis(pyridine-2-aldimine) (L), was synthesized and structurally characterized by x-ray crystallog. In the six-coordinate Fe(II) complex, ligands L' and L'' show tetradentate and bidentate chelating modes of bonding, resp. Ligand L' is formed from an intramol. attack of the alc. OH group of L to one imine moiety giving a stereochem. constrained five-membered ring. Ligand L'' which is formed from an intermol. 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 √ó 105 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 O as the reactive species. [on SciFinder(R)]