CU(II) and MN(II) Complexes Containing Macroacyclic Ligand: Synthesis, DNA Binding, and Cleavage Studies

Abstract

The two new metal complexes of Cu(II) and Mn(II) containing macroacyclic ligand of the type [Cu(hpn)](PF₆)₂ (1) and [Mn(hpn)](PF₆)₂ (2) [where hpn = [1-{[2-{[2-hydroxynaphthalen-1-yl)methylidine]amino}phenyl)imino]methyl}naphthalene-2-ol]] have been synthesized and characterized by employing analytical and spectral methods. The DNA binding properties of the complexes with calf thymus-DNA were studied by using absorption spectra and viscosity measurements, as well as thermal denaturation experiments. The absorption spectra indicated that the complexes intercalate tightly between the base pairs of the DNA with intrinsic DNA binding constants of 1.8 × 10⁴ M⁻¹ for (1) and 3.7 × 10⁴ M⁻¹ for (2) in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2, respectively. The enhancement in the relative viscosity of DNA on binding to the ligand supports the proposed DNA binding modes. The oxidative cleavage activity of complexes (1) and (2) were carried out on double-stranded pUC19 circular plasmid DNA using gel electrophoresis. The complexes show significant nuclease activity.

Keywords:

• Cu(II)
• Mn(II) complexes
• DNA
• oxidative cleavage

Acknowledgments

The authors are thankful to Sri B. Premanath Reddy, Chairman, Acharya Institutes, and Prof. G.P. Prabhukumar, Principal, Acharya Institute of Technology, Bangalore, India. They are also thankful to Department of Industrial Chemistry, Kuvempu University, Shankaraghatta, Shimoga, Karnataka, India.