Synthesis and crystal structure of a series of pyrazolone based Schiff base ligands and DNA binding studies of their copper complexes

PMP (5-methyl-4-(4-methyl-benzoyl)-2-phenyl-2,4-dihydro-pyrazol-3-one), PTPMP (5-methyl-4-(4-methyl-benzoyl)-2-p-tolyl-2,4-dihydro-pyrazol-3-one) and MCPMP (2-(3-Chloro-phenyl)-5-methyl-4-(4-methyl-benzoyl))-2,4-dihydro-pyrazol-3-one) were synthesized and used for the synthesis of Schiff base ligands. Schiff base ligands were characterized by FT-IR, 1H NMR, Mass and single crystal X-ray analysis. Cu(II) complexes of synthesized ligands were prepared and characterized by elemental analysis, FT-IR, TGA–DTA, UV–Visible, ESI mass and ESR spectroscopy. On the basis of analytical and spectroscopic techniques, distorted octahedral geometry of the complexes was proposed. The interaction of Cu(II) complexes with CT-DNA was investigated by Absorption titration, Viscosity and fluorescence spectroscopy. Results suggest that the synthesized complexes bind to DNA via an intercalative mode and can quench the fluorescence intensity of EB bound to DNA.