Schiff base coordination compounds including thiosemicarbazide derivative and 4-benzoyl-1,3-diphenyl-5-pyrazolone: Synthesis, structural spectral characterization and biological activity

A new thiosemicarbazone ligand containing an allyl group and a 5-pyrazolone derivative has been prepared. The reaction of this ligand (H2L) with chloride and nitrate salts of Co(II), Cu(II), Pd(II), and Ni(II), Cu(II) ions resulted in the formation of different chelates having variable chemical formulas. Structural characterization of H2L ligand and its chelates has been established employing microanalytical, molar conductivity, magnetic moment measurements as well as spectral techniques including IR, UV-vis, NMR, mass, XRD, and ESR spectra. The spectral and microanalytical data achieved the monobasic tridentate binding mode with the metal(II) ion through SNO and NNO donor sites in complexes (2,5) and (3,4), respectively. In addition, the thiosemicarbazone ligand acts as a neutral bidentate species (NS) and neutral or mononegative bidentate species (NO) in complexes (6) and (1), respectively. Based on electronic spectra analyses (UV-vis) and magnetic moment measurements, all chelates, with the exception of those of Co(II) and Pd(II) ions, which have square planar geometrical structures, revealed a square pyramidal structure. Furthermore, the ESR spectra of Cu(II) chelates (3-5) have been inves-tigated, yielding 2B1g as an axial ground state. The chemical formulae for the metal chelates were determined using thermogravimetric investigations (TG and DTG), demonstrating both their thermal stability and the presence of various crystalline solvents. Metal oxide (MO) or metal with traces of carbon was the residue of the thermal degradation processes. Based on XRD analysis, the structures of allopalladium (O-dopped Pd), mono-clinic CuO, and tetragonal metallic cobalt nanoparticles obtained thermally from chelates (1,3,4,6) were elucidated. Copper(II) chelates (3) and (4) display the highest anticancer activity against hepatocellular carci-noma cells (Hep G-2) testes, according to the biological studies for the ligand and some of its chelates.

Automated summary

A new thiosemicarbazone ligand containing an allyl group and a 5-pyrazolone derivative was synthesized. The ligand reacted with chloride and nitrate salts of Co(II), Cu(II), Pd(II), and Ni(II), Cu(II) ions, resulting in the formation of different chelates with variable chemical formulas. Structural characterization of the ligand and its chelates was established using various spectroscopic and analytical techniques. The chelates exhibited square pyramidal structures, except for those of Co(II) and Pd(II) ions, and copper(II) chelates showed the highest anticancer activity against hepatocellular carcinoma cells (Hep G-2) in biological studies.