Anticancer activity, structure, and theoretical calculation of N-(1-phenyl-3-methyl-4-propyl-pyrazolone-5)-salicylidene hydrazone and its copper(II) complex

The pyrazolone derivative N-(1-phenyl-3-methyl-4-propyl-pyrazolone-5)-salicylidene hydrazone (H₂L) and its copper(II) complex Cu₂L₂CH₃OH]·2CH₃OH have been both synthesized and characterized by elemental analyses, IR spectroscopy, X-ray crystallography, theoretical calculation and pharmacological testing. It’s found that the Cu(II) complex possesses more powerful anticancer effectivity than that of the ligand. In order to make its anticancer principium clearly, we investigate their structures. In ligand there are several coordination spots, such as N, O atoms, which are close to biological environment. The crystallographic structural analysis of the complex reveals that the two Cu centers display two different coordination patterns. O1, O2, N3, and N4 from the ligand take part in the coordination with Cu atoms, resulting in the formation of the double-nuclear complex. The pharmacological testing results show that the coordination effect improves the antitumor activity of the ligand. The calculated Fukui function for H₂L and its deprotonated form L²⁻ predicts that the most probable reactive sites for electrophilic attack are oxygen atoms. The result is agreement well with the experimental data of the crystal structure analyses.