Synthesis, Structural Elucidation, Cytotoxic activity and Plant Growth Studies of Some Novel Schiff Base Cobalt(II) and Nickel(II) Complexes of Sulfur/Oxygen and Nitrogen Donor Agents

Abstract Eight metal complexes with Schiff base ligands, HL1 [2-{1-(2-fluorophenyl)ethyledene}] hydrazinecarboxamide and HL2 [2-{1-(2-fluorophenyl)ethyledene}] hydrazinecarboxathioamide were synthesized with Co(II) and Ni(II). These were characterized by analytical as well as various spectroscopic techniques like FT-IR, 1H NMR, electronic absorption spectra. The spectral results revealed the formation of octahedral complexes. To determine the concentration of cobalt in Schiff base metal complex flame atomic absorption spectroscopy (FAAS) was done. The accuracy of results was verified by inductively coupled plasma mass spectroscopy (ICP-MS). In vitro cytotoxic activity of the ligands HL1, HL2 and their Schiff base metal complexes was examined, in which A549 (human lung cancer cell line) and L929 (mouse normal fibroblast cell line) were used in the screening test. Among all the synthesized Schiff base ligands and metal complexes, Ni(II) thiosemicarbazone based complex i.e. (Ni (L2)2.2H2O) exhibited a significant cytotoxic effect towards A549 cell line with a mean IC50 value of 36.43 μΜ. Plant growth regulatory activity of the ligands (HL1, HL2) and their metal complexes have also been performed on chick pea plant. The PGR activity of the ligands and their complexes were compared and it was found that the thiosemicarbazone based metal complexes possess higher PGR activity. GRAPHICAL ABSTRACT