Structural Characterization and Antimicrobial Activity of 2-(5-H/methyl-1H-benzimidazol-2-yl)-4-bromo/nitro-phenol Ligands and their Fe(NO3)3 Complexes

2-(5-H/methyl-1H-benzimidazol-2-yl)-4-bromo/nitro-phenol (HL_x:X=1–4) ligands and their iron(III) nitrate complexes have been synthesized and characterized. In all of the complexes, the ligands are bidentate, via one imine nitrogen atom and a phenolate oxygen atom. The coordination is completed with a bidentate nitrate anion, and a water molecule. Elemental analysis, molar conductivity, magnetic susceptibility, FT-Raman, FT-IR (mid i.r., far i.r.), UV–visible and as well as quantum chemical calculations performed with CACHE are in agreement with a 1:1 electrolyte structures that are mononuclear, and distorted 5-coordinate square pyramidal. The antimicrobial activities of free ligands, their hydrochloride salts and the complexes were evaluated using the disk diffusion method in dimethyl sulfoxide (DMSO) toward nine bacteria, each with multiple, fresh clinical isolates, and the results are compared with those for penicillin-g, ampicillin, cefotaxime, vancomycine, oflaxacin and tetracycline. Antifungal activities were reported for Kluyveromyces fragilis, Rhodotorula rubra, Candida albicans, Hanseniaspora Guilliermondii and Debaryomyces hansenii yeasts, each with multiple isolates, and the results were referenced against nystatin, ketaconazole and clotrimazole antifungal agents. In most cases, the compounds tested showed broad-spectrum (Gram⁺ and Gram⁻) activities that were either more active or as potent as the references particularly as antifungal agents.