Synthesis, crystal structure, DNA binding and cleavage studies of copper(II) complexes with isoxazole Schiff bases

Abstract

Three novel binary copper(II) complexes 1 [Cu(L1)2], 2 [Cu(L2)2] and 3 [Cu(L3)2] where, L1 (1-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)naphthalen-2-ol, C16H14N2O2), L2 (2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-4-methoxyphenol, C13H14N2O3) and L3 (2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-4-bromophenol, C12H11BrN2O2) have been synthesized. All Cu(II) complexes have been characterized by elemental analysis, FT-IR, ESI mass, UV–Vis, ESR, TG-DTA, magnetic moments and single crystal X-ray diffraction studies. Based on spectral studies square planar geometry is assigned for all Cu(II) complexes. Ligand L1, [Cu(L1)2] and [Cu(L2)2] are crystallized and found to be triclinic, orthorhombic and monoclinic crystal systems respectively. The Schiff bases and their Cu(II) complexes have been screened for antibacterial activity and antifungal activity by paper disc method. It is observed that all Cu(II) complexes showed more activity than corresponding Schiff bases. DNA binding and cleavage studies of Cu(II) complexes have also been investigated. It is observed an intercalation mode of binding with CT-DNA and cleavage of supercoiled pBR322 DNA in the presence of H2O2 and UV light.