Synthesis, structure and DNA cleavage of mononuclear Fe(III) complexes with 1,2,4-triazole-base ligand

Two new mononuclear iron(III) complexes, [Fe(HL)(2)](ClO4) center dot (H2O)(1.75) center dot CH3CN (1) and [Fe(HL)Cl-2] center dot DMF (2) (H2L = 3-(2-phenol)5-(pyridin-2-yl)-1,2,4-triazole) have been synthesized and characterized by X-ray single-crystal structure analysis. The single crystal X-ray crystallographic studies reveal that the central iron atom has a distorted octahedral environment for 1 and a distorted square pyramidal geometry for 2. The DNA cleavage activity of the iron(III) complexes was measured, indicating that the six-coordinated iron(III) (complex 1) was cleavage inactive and only five-coordinated complex 2 effectively promoted the cleavage of plasmid DNA in the presence and/or absence of activating agents (peroxide oxygen) at physiological pH and temperature. The mechanism of plasmid DNA cleavage was also studied by adding standard radical scavengers. Copyright (C) 2010 John Wiley & Sons, Ltd.