Synthesis, crystal structures and biological activities of transition metal complexes of a salen-type ligand

Manganese(III), cobalt(II), nickel(II) and copper(II) complexes of a salen-type ligand, namely 6,6'-((1E,1'E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(5-isopropyl-2-methylphenol) (H2L), have been synthesized and characterized by physicochemical and spectroscopic methods. In addition, single-crystal X-ray analysis confirmed the formulae of the manganese and nickel complexes as [Mn(OAc)(L)] and [Ni(L)], respectively. The free Schiff base and its complexes have been screened for in vitro antibacterial activity by colony count methods, and the antioxidant activity was assayed by DPPH radical scavenging. The ability of free H2L and its complexes to mediate DNA cleavage was studied by agarose gel electrophoresis.