New transition metal complexes of 2,4-dihydroxybenzaldehyde benzoylhydrazone Schiff base (H2dhbh): Synthesis, spectroscopic characterization, DNA binding/cleavage and antioxidant activity

Abstract New complexes [VO 2 (Hdhbh)] ( 1 ), [VO(phen)(dhbh)].1.5H 2 O ( 2 ), [Zn(Hdhbh) 2 ] ( 3 ), [MoO 2 (dhbh)(D)] (D = H 2 O ( 4 ) or MeOH ( 5 )), [Ru(PPh 3 )(dhbh)Cl(H 2 O)] ( 6 ), and [Pd(Hdhbh)Cl]·H 2 O ( 7 ) (H 2 dhbh = Schiff base derived from 2,4-dihydroxybenzaldehyde and benzoylhydrazone) have been isolated and characterized by IR, 1 H NMR, Mass, UV–Visible and ESR spectroscopy. They were also investigated by cyclic voltammetry, thermal and magnetic measurements and the structure of complex cis -[MoO 2 (dhbh)(H 2 O)] ( 4 ) was solved by X-ray crystallography. Analytical data showed that H 2 dhbh behaves as monobasic/or dibasic tridentate ligand via phenolate O, azomethine N and amide O/or deprotonated amide O atoms. Antioxidant activity of the complexes has been evaluated against DPPH (2,2-diphenyl-1-picrylhydrazyl) radical and it has been found that oxovandium (IV) complex ( 2 ) displays the highest radical scavenging potency comparable to ascorbic acid as a standard antioxidant. The DNA binding properties of the ligand and its complexes have been investigated by electronic spectroscopy together with DNA cleavage by gel electrophoresis whose results showed also that vanadium (IV) complex ( 2 ) has a significant oxidative cleavage among other complexes.