Synthesis, characterization, X-ray crystal structure, antioxidant, antimicrobial, and DNA binding interaction studies of novel copper (II)-isoxazole binary complexes

Abstract

Cu (II) binary complexes of the type [Cu(HLx)2], where x = 1–3, HL1 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-methylphenol (C1), HL2 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-ethoxyphenol (C2) and HL3 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-4,6-di-tert-butylphenol (C3) have been synthesized and characterized by various analytical, structural, and spectral methods. Single crystal X–ray diffraction analysis of ligand HL1, complexes C2 & C3 revealed that the compounds are crystallized in monoclinic crystal system with the space groups of P1 21/c1 for HL1 & C2, and P1 21/n1 for C3. The antioxidant studies of the synthesized Cu(II) complexes were carried out and it was shown as significant activity against DPPH radical. The synthesized Schiff bases and Cu(II) complexes were explored for antimicrobial activities and the complexes exhibited better potency against diverse microorganisms compared to Schiff bases as ligands. The interaction of Cu(II) complexes with CT–DNA has been explored with absorption and emission spectral techniques and the obtained results were evidence to the intercalative mode of DNA binding. The study of Agarose gel electrophoresis was resulted in three Cu(II) complexes stimulate the double strand breakage of pBR 322 plasmid DNA in the presence and absence of H2O2.

Keywords

• Isoxazole Schiff base
• Cu(II) binary complex
• Crystal structure
• Antioxidant activity
• Antimicrobial activity
• DNA interaction