Mn(II) complexes with bipyridine, phenanthroline and benzoic acid: Biological and catalase-like activity

Five mononuclear Mn(II) complexes, [Mn(phen)(2)(ClO4)(2)] (1), [Mn(phen)(3)](ClO4)(2)(H2CO3)(2)(2), [Mn(bipy)(2)(ClO4)(2)] (3), [Mn(bipy)(3)](ClO4)(2)) (4), and Mn(phen)(2)(ba)(H2O)](ClO4)(CH3OH) (5), where bipy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and ba = benzoic acid were prepared and characterized by X-ray, IR and UV-Vis spectroscopies, and their catalase-like and biological activities were studied. The presence of two different types and the number of chelating NN-donor neutral ligands allowed for analysis of their effects on the catalase and biological activities. It was observed that the presence and number of phen ligands improved the activity more than the bipy ligand. Complexes 1 and 2, which contain more basic phen ligands, disproportionate H2O2 faster than complexes 3 and 4, which contain less basic bipy ligands. The in vitro antimicrobial activities of all the complexes were also tested against seven bacterial strains by microdilution tests. All the bacterial isolates demonstrated sensitivity to the complexes and the antifungal (anticandidal) activities of the Mn(II) complexes were remarkably higher than the reference drug ketoconazole.