Synthesis, characterization and biological properties of mixed ligand complexes of cobalt(II/III) valproate with 2,9‐dimethyl‐1,10‐phenanthroline and 1,10‐phenanthroline

The synthesis of mononuclear cobalt(II/III) complexes with two different ligands (complex 2: [Co(valp)2(2,9-dmp)] and complex 3: [Co(valp)2(H2O)(1,10-phen)]) was investigated and the characterization of both complexes was achieved using IR, UV–Vis, and single crystal X-ray diffraction. Using single crystal X-ray diffraction, the crystal structure of each of the complexes was determined. Additionally, the biological activity of these complexes was studied in five gram-positive and four gram-negative bacterial strains. Whereas in all gram-negative bacteria tested, cobalt valproate complexes did not show any anti-bacterial activity, both complexes had effects on gram positive bacteria. Complex 2 demonstrated good anti-bacterial activity against all gram-positive bacteria with inhibition zone diameter (IZD) ranging between 15–28 mm. Complex 3 exhibited low inhibition activity against all gram-positive bacteria except E. faecalis with IZD ranging between 11.3–13.7 mm. Moreover, as an indication of its uses as industrial catalyst, the rate of bis(p-nitrophenyl) phosphate (BNPP) hydrolysis when catalyzed by these complexes was measured at different temperatures, concentrations and pH. Complex 2 proved to be a better catalyst to induce the hydrolysis of BNPP.