Transition metal complexes of asymmetrical aroyl-hydrazone ligand: Syntheses, structures, DNA binding and cleavage studies

• H21 and its metal complexes were prepared and structurally characterized.
• H1− or 12− is hold onto cis-isomer after coordinating to metals.
• The larger charge-radius ratio of metals shows higher nuclease activity.

Syntheses and crystal structures of aroyl-hydrazone ligands and their transition metal complexes (E)-N′-(2-hydroxybenzylidene)-1-methyl-4-nitro-1H-pyrrole-2-carbohydrazide (H21), [CuII(H1)Cl] (2), [FeIII(H1)Cl2(MeOH)] (3), [MnIII(1)(μ-OMe)(MeOH)]2 (4), [VVO(1)(OMe)] (5), Et3NH[VVO2(1)] (6), [CoII(H1)(μ-Cl)(H2O)]2 (7) and [CoII(1)2] (7′) are reported in this paper. The binding abilities of the compounds with calf thymus DNA are measured by using UV–Vis and fluorescence spectra. The apparent binding constant (Kobs = (1.66 ± 0.21) × 104 M−1) and rate constant (kobs = 3.62 ± 0.17 h−1) of 2 with CT-DNA is calculated, respectively. The quenching constants (Kq) 3.52 × 104 for 3, 1.97 × 104 for 4, 5.94 × 103 for 2, 3.32 × 103 for 7, 1.64 × 103 for 5, 1.55 × 103 M−1 for H21 are determined, respectively, using ethidium bromide, as fluorescence probe. Agarose gel electrophoresis studies indicated that the complexes cleave plasmid pBR322 DNA by a hydrolytic mechanism.

(E)-N′-(2-hydroxybenzylidene)-1-methyl-4-nitro-1H-pyrrole-2-carbohydrazide (H21) and its transition metal complexes 2–7, 7′ are synthesized and characterized. The binding abilities of the compounds with calf thymus DNA are measured by using UV–Vis spectra. The quenching constants are determined by using ethidium bromide as fluorescence probe. Agarose gel electrophoresis studies indicated that the complexes cleave plasmid pBR322 DNA by a hydrolytic mechanism.Figure optionsDownload as PowerPoint slide