Synthesis and the characterization of Schiff-base copper complexes: Reactivity with DNA, 4-NPP and BNPP

摘要

Two new copper Schiff-base complexes have been synthesized and characterized by use of spectroscopic techniques. The Schiff-base ligands, (E)-N-((1-methyl-1H-imidazol-2-yl)methylene) quinolin-8-amine, MICQ and (E)-1-((quinolin-8-ylimino) methyl)naphthalen-2-ol, TL1 were obtained from the reaction of 8-aminoquinoline with 1-methyl-2-imidazolecarboxaldehyde and 2-hydroxy-1-napthaldehyde respectively. The reaction of MICQ with copper(II) chloride produced complex 1, [Cu(MICQ)Cl](PF6), whereas the reaction of TL1 with copper(II) acetate resulted in complex 2, Cu(TL1)(OAc)center dot CH3OH. The single crystal X-ray structure determination of both complexes show distorted square planar geometries around the copper center. The reactivity of the complexes with calf thymus DNA, CT-DNA and plasmid DNA have been studied using ethidium bromide displacement fluorescence emission, electronic absorption spectroscopy and agarose gel electrophoresis analysis. From the fluorescence emission studies K-sv values of 3.70 x 10(3) M-1 and 7.82 x 10(3) M-1 were obtained for complexes 1 and 2, respectively. The absorption titration resulted in K-b values of 1.52 x 10(5) M-1 for complex 1 and 5.00 x 10(5) M-1 for complex 2. The results indicate that both complexes significantly interact with CT-DNA and also show cleavage of supercoiled DNA. In addition, complex 2 was found to hydrolyze the DNA model compounds bis(4-nitrophenyl) phosphate, BNPP and 4-nitrophenyl phosphate, 4-NPP. (C) 2015 Elsevier B.V. All rights reserved.