Synthesis, characterization and antioxidant activity of some transition metal complexes with terpenoid derivatives

Abstract

A series of transition metal complexes of Fe(III), Co(II) and Cu(II) containing the bidentate N,O and N,S donor ligand, camphor semicarbazone (1,7,7-trimethylbicyclo [2,2,1]heptanesemicarbazone, TBHSC) and camphor thiosemicarbazone (1,7,7- trimethylbicyclo [2,2,1]heptanethiosemicarbazone, TBHTSC) have been synthesized and characterized by elemental analysis, molar conductance measurement and various spectral studies (IR, electronic and FAB Mass) and thermogravimetric analysis (TGA). All the metal complexes (1-8) are [M(LH)Cl2] and [M(LH)2Cl2] type, where M = Fe(III), Co(II) and Cu(II); LH = TBHSC and TBHTSC. TBHSC and TBHTSC act as neutral bidentate ligands in all the complexes. FAB mass spectroscopic studies of the three representative complexes (1), (2), (4), (5) and (8) suggest their monomeric nature. The proposed geometries of the complexes were octahedral geometry for1:2 complexes, square planar for 1:1 complexes and distorted octahedral for Cu(II) complexes (1:2). The free radical scavenging activity of newly synthesized ligands (TBHSC, TBHTSC) and their metal complexes have been determined at the concentration range of 50-1000 μg/ml by means of their interaction with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). All the compounds have shown encouraging antioxidant activities. The least IC50 value (111.0 μg/ml) for compound (5) showed the potent scavenging property compared to other test compounds.