Synthesis, and biological evaluation of complexes based on thiosemicarbazone ligand

Synthesis and evolution of antioxidant and antitumor compounds is a prominent discipline of science. New ligand, 3-(4-hydroxyphenyl)-1-phenyl-1h-pyrazole-4-carbaldehyde 4N-(2-pyridyl)thio-semicarbazone (H2L) and its complexes [Mn2HLCl3(H2O)(5)]H2O, [CoH2LCl2(H2O)(2)]H2O, [NiHLCl(H2O)(2)] H2O, [CuH2LCl2], [ZnHL(CH3COO)(H2O)(2)]H2O and [CdHL(CH3COO)(H2O)(2)]H2O were isolated and characterized by diverse spectroscopic studies, electronic absorption spectral studies and magnetic studies. From IR spectra of H2L behaves in a bidentate, tridentate or tetradentate way. DFT calculations showed that the highest occupied molecular orbitals (HOMO) of the complexes are located mainly on the metal and sulphur atoms, whereas the lowest unoccupied molecular orbitals (LUMO) are essentially centered on both the N-heterocyclic core and the largely delocalized thiosemicarbazone backbone. The kinetic and thermodynamic parameters for each stage of decomposition step were calculated from thermal data. It has been found that although H2L proved to exhibit potent antioxidant activity followed by Mn(II), Cd(II), Zn(II) and Ni(II) complexes using ABTS assay. Cobalt complex can be promoted as better antioxidant agent as DPPH radical scavenging activity. Finally, H2L showed the highest cytotoxic activity followed by Mn(II), Ni(II), Cd(II), Zn(II), and Cu(II) complexes. (C) 2019 Elsevier B.V. All rights reserved.