Synthesis, structure, redox properties and DNA interaction studies on mononuclear iron(III) complexes with amidate ligand

A new family of mononuclear Fe(III) complexes [Fe(Pamp)(MeOH)Cl2], 1 and [Fe(Pamp)2](ClO4), 2 were synthesized using designed tridentate ligand PampH having pyridine and amide nitrogen donors (PampH is N′-phenyl-N′-(pyridin-2-yl)picolinohydrazide) and H stands for dissociable proton). Both the complexes (1 and 2) were characterized by different spectroscopic studies and molecular structure of [Fe(Pamp)2](ClO4), 2 was determined by single crystal X-ray diffraction. Geometry around metal centre was described as distorted octahedral with two meridionally oriented Pamp− ligands. Electrochemical studies afforded E1/2 values of Fe(III)/Fe(II) couple +0.065 V (for 1) and −0.077 V (for 2) versus Ag/AgCl electrode. DNA binding properties of these complexes were investigated and complex 1 exhibited nuclease activity. Mechanistic investigation revealed the possible participation of hydroxyl radical in nuclease activity which was supported by rhodamine B assay.