Synthesis, spectral studies and nuclease activity of mixed ligand copper(II) complexes of heteroaromatic semicarbazones/thiosemicarbazones and pyridine

Pyridine adducts of copper(II) complexes with thiosemicarbazones and semica rbazones have been synthesized and characterized using elemental analyses, molar conductance, IR spectra, magnetic measurements, electronic and ESR sp ectra. Copper(II) adducts show quasireversible responses (Delta E-p = 100 m V) in cyclic voltammograms with E-1/2 = 0.510-0.535 V versus Ag\AgCl at roo m temperature in N,N-dimethylformamide, attributable to a Cu-III/Cu-II coup le. The spectral studies support the distorted octahedral geometry of these copper(II) adducts. The nucleolytic cleavage activity of all the copper(II ) adducts was carried out on double-stranded pBR 322 circular plasmid DNA b y using the gel electrophoresis experiment in the presence and absence of o xidant (H2O2). In the absence of oxidant a less discernible DNA cleavage wa s observed, whereas in the presence of oxidant (H2O2) all adducts showed in creased nuclease activity. (C)1999 Elsevier Science Inc. All rights reserve d.