Synthesis, spectroscopic characterization and biological applications of some novel Schiff base transition metal (II) complexes derived from curcumin moiety

Schiff bases are considered as privileged ligand in coordination chemistry as they easily form stable complexes with most transition metal complexes. In this paper, a novel Schiff-base ligand derived from Curcumin and Semicarbazide (HMHC) and its transition metal [Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)] complexes were synthesized. FT-IR, UV–Vis, NMR, Mass, TG-DTA and ESR spectral techniques were used to confirm the structures of the metal chelates and ligand. The Schiff base behaves as a tridentate ligand with O and N donors and coordinates to metal ion via phenolic oxygens and azomethine nitrogen. The compositions of the ligand and its metal complexes have been established by elemental analysis. Spectral investigations suggested octahedral geometrical arrangement for all the metal(II) complexes, having 2:1 (L:M) stoichiometric ratio of the type [M(HMHC)2]H2O. The Schiff base ligand and its metal complexes have been screened for antimicrobial evaluation towards some clinically important microorganisms. Result found that the metal complexes were more active than the ligand. Also anti-inflammatory activity of Schiff base complexes were studied by protein denaturation method and result reveals that Zn(II) complex shows more activity.