Synthesis, spectroscopic, crystal structure and DNA binding of Ru(II) complexes with 2-hydroxy-benzoic acid [1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3- yl)-ethylidene]-hydrazide

Reactions of 2-hydroxy-benzoic acid [1-(4-hydroxy-6-methyl-2-oxo-2H-pyran- 3-yl)-ethylidene]-hydrazide (H ₂L) with [RuHCl(CO)(EPh ₃) ₃] (E = P or As) were carried out and the new complexes obtained were characterized by elemental analysis, electronic, IR, ¹H NMR and ¹³C NMR spectroscopic techniques and single crystal X-ray diffraction studies. Complex (1) crystallizes in the monoclinic space group P2(1)/c with unit cell dimensions a = 18.6236(17) , b = 12.8627(12) , c = 21.683(2) , α = 90.00, β = 114.626(2), γ = 90.00 V = 4721.8(8) , Z = 4. The crystal structure of the complex shows Ru(II) atom is six-coordinated, forming a slightly distorted octahedral geometry with two P atoms in axial positions, and three chelating donor atoms of the tridentate Schiff base ligand and one carbonyl group located in the equatorial plane. The molecular structure is stabilized by intramolecular O - H·· ·N interactions. No intermolecular hydrogen bond was observed. The intramolecular hydrogen bond exists between the oxygen atom from salicylic acid moiety and nitrogen from the same moiety. A variety of solution studies were carried out for the determination of DNA binding mode of the complexes. The results suggest that both complexes bind to Herring sperm DNA via non intercalative mode.