The biological activities of 1,4-bis(o-aminobenzyl)-1,4-diazacycloheptane (L) and the copper(II) and nickel(II) complexes, [CuL](ClO4)2 and [Ni(L)(NCMe)2](ClO4)2. NCMe, were investigated. The X-ray structural analysis of the latter complex shows that the nickel(II) ion is in a slightly distorted octahedral coordination environment coordinated by four nitrogen atoms of the ligand with two molecules of acetonitrile in the trans configuration. The binding behavior of the ligand and corresponding Cu(II) and Ni(II) complexes with DNA and acetylcholinesterase (AChE) was investigated by molecular modeling. These studies indicated that the copper complex was bound to the major groove of DNA and polar and non-polar residues located in the active-site gorge (binding site of E2020) of AChE. The binding constants obtained from the molecular docking results showed a remarkably high affinity of the Cu(II) complex to both DNA and AChE compared to the ligand and the nickel(II) complex. Further investigations demonstrated that the synthesized complexes, especially [CuL](ClO4)2, had a strong ability to scavenge DPPH free radicals. The anticancer activity of the ligand and related complexes was also assessed, using the MTT test, which found that the highest activity was observed for [CuL](ClO4)2 against breast cancer (MCF-7) cells.
