Metal chelates have also been used as agents for mediation of strand scission of duplex DNA and as chemotherapeutic agents.1,

2, 3, 4, 5, 6, 7, 8, 9 and 10 With the aim of cleaving DNA efficiently by either hydrolytic,11, 12, 13, 14, 15, 16, 17, 18, 19 and 20 check details or oxidative pathways,21 a number of metal complexes has been explored. Copper is a biologically relevant element and many enzymes that depend on copper for their activity have been identified. Copper(II) is a substitutionally labile metal ion. So multidentate ligands are believed to be better than bidentate ligands in keeping the copper(II) ion chelated in solution. Typically, upon association with dioxygen or hydrogen peroxide these copper complexes are thought to perform reactive intermediates. Sigman et al have shown that the bis(phen) copper complex acts as an efficient nuclease by oxidative cleavage mechanism in the presence of molecular oxygen and a reducing agent.22, 23, 24 and 25 By using their redox properties, Palaniandavar et al exemplified the nuclease activity of copper(II) bis complexes

of various methyl-substituted 1,10-phenanthrolines.26 Depending on the reaction conditions, the mechanistic pathways in the oxidative cleavage process generally involve abstraction of sugar hydrogen, electron transfer or guanine base oxidation. Such cleavage products formed via oxidative process are not readily amenable to further enzymatic manipulations. The present work stems from our interest to design mixed ligand copper(II) Raf inhibitor drugs complexes with tetrahydro furyl amine based ligands and planar NN-donor heterocyclic ligands. We have synthesized a series of copper complexes [Cu(L1)(phen)](ClO4)2, [Cu(L1)(phen)](ClO4)2,

and [Cu(L1)(phen)](ClO4)2 where L1 and L2 are tetrahydro furyl amine based unsymmetrical tridentate ligands. 1-(tetrahydrofuran-2-yl)methanamine, thiophene-2-carbaldehyde, copper(II) perchlorate hexahydrate, 2,2′-bipyridine, no 1,10-phenanthroline, agarose (molecular biology grade) and ethidium bromide were procured from Sigma Aldrich, USA and used as received. Other materials like sodium borohydride and solvents like methanol, acetonitrile and dichloromethane were of reagent grade. Benzimidazole carbaldehyde was prepared using published procedure.27 Buffers were prepared using deionized and sonicated triple distilled water. Tris (hydroxymethyl) aminomethane–HCl (Tris–HCl) buffer (pH, 7.2) was used for DNA cleavage studies. UV–visible spectra of the complexes were recorded on a Perkin–Elmer Lambda 35 double beam spectrophotometer at 25 °C. Electron paramagnetic resonance spectra of the copper(II) complexes were obtained on a Varian E 112 EPR spectrometer. IR spectra were recorded as KBr pellets in the 400–4000 cm−1 region using a Shimadzu FT-IR 8000 spectrophotometer.