Curcumin derived Schiff base ligand and their transition metal complexes: Synthesis, spectral characterization, catalytic potential and biological activity

Abstract

Curcumin derived Schiff base ligand, (CL), was prepared by condensation of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) with amino ethylene piperazine (AEP). The transition metal complexes of CL were also successfully synthesized and characterized by various spectroscopic techniques. Non-electrolytic nature of complexes was ascertained by molar conductance values. Thermogravimetric analysis confirms that all the metal complexes are stable up to 600 °C. The metal to ligand stoichiometry of synthesized metal complexes was confirmed by micro analytical data as 1:1 (metal: ligand). Co(II), Ni(II) and Zn(II) ion forms the complexes with an octahedral geometry while the geometry of Cu(II) complex can ascribed as square planar by UV–vis and EPR spectroscopic studies. Catalytic power and antioxidant activity of these complexes have been evaluated and results shows that Co(II) complex is catalytically more active while the Cu(II) and Zn(II) complex were found with more potent antioxidant activity, comparatively. The synthesized compounds have also been tested for their in-vitro cytotoxic potential, the obtained results shows moderate to good cytotoxicity on tested human cancer cell lines. The most effective compounds on cell lines MDA-MB-231 and KCL22 was [(CL)Cu] while on HeLa cell line the [(CL)Zn(H2O)2] was found with prominent cytotoxicity. Anthelmintic activities of these compounds have been performed using Pheretima posthuma. The recorded order of anthelmintic activity of ligand (CL) and their metal complexes was found to have the trend as: [(CL)Cu]>[(CL)Zn(H2O)2]>[(CL)Co(H2O)2]>[(CL)Ni(H2O)2]>CL.