The new magnetic-supported benzoguanamine-based nickel complex was prepared, characterized by var- ious procedures and used as a capable heterogeneous nano-catalyst for the synthesis of diverse 2-phenyl- 1 H -benzo[ d ]imidazoles from the reaction o -phenylenediamine (PhenDA) with various aldehydes in chlo- roform at reflux conditions. Then, the biological (anti-oxidant, anti-bacterial and anti-cancer) activities of the nickel complex were studied. The antioxidant properties of the complex were investigated using the DPPH assay at six different concentrations. The results show that the antioxidant properties of the catalyst are directly proportional to its concentration, and as the concentration increases, its antioxidant properties also increase. In addition, results from the two antibacterial assays of minimum inhibitory concentration (MIC) and disk diffusion methods (DDM) showed that the catalyst could impair the growth of both the gram-positive and the gram-negative bacteria in all tested concentrations. In agreement with MIC, the inhibitory activity of catalyst on S. aureus was more than that on E. coli in disk diffusion method. Incidentally, the anticancer (proliferative) activity of the Ni-complex was investigated against the MG63 cell line. The ratio of cell viability under the catalyst treatment has shown a considerable decrease com- pared to Cisplatin as the positive control confirming its anticancer property. The IC 50 value determined the growth inhibition of cancer cells, indicating that the compound concentration was associated with the half inhibition of the cancer cell growth.
