The crystal structure of first copper(II) complex of a pyridine-2-carboxamidrazone – a potential antitumor agent

The crystal structure of the neutral, distorted square planar copper(II) complex, viz. cis-[dichloro (N1-(2-benzyloxybenzylidene) pyridine-2-carboxamidrazone) copper(II)] (1) is reported which is the first well-characterized copper(II) complex of the series (space group C2/c; a=18.414(5) Å; b=8.6510(10) Å; c=27.091(4) Å; α=90°; β=109.800(17)°; γ=90°; R1=0.0331 wR2=0.0852). The distortion from square planar geometry is thought to arise from the non-equivalent ligand donor set. The Cu–Cl bonds are equivalent with one of the Cl atoms making intermolecular contact at 2.6070 Å with adjacent copper rendering a pseudo-square pyramidal geometry around copper. The complex is further characterized by UV/VIS spectroscopy, electrochemistry and magnetic susceptibility measurements. The in vitro antitumor activity of this complex and the parent ligand is determined against the human breast cancer cell-line MCF-7 which revealed that copper complexation renders a highly antiproliferative compound with IC50 value of 3 μM.