Synthesis, structural characterization and prospects for a new tris (5-methylbenzimidazole) tris (oxalato) ferrate(III) trihydrate complex as a promising antibacterial and antifungal agent

Abstract

Abstract A new mononuclear complex (C8H9N2)3[Fe(C2O4)3].3H2O was synthesized via a conventional solution method and characterized by FT-IR and UV–visible spectroscopy, followed by thermal analysis and single crystal X-ray diffraction. The molecular structure of the complex reveals [Fe(C2O4)3]3− octahedral anions and 5-methylbenzimidazole (C8H9N2)+ cations, which are connected together through uncoordinated water molecules via O/N H⋯O hydrogen bonds. Face-to-face interactions (π–π stacking) between identical organic cations and O/N H⋯O hydrogen bonding lead to the formation of a three-dimensional supramolecular architecture. The optical absorbance of the complex was identified from a UV–visible study, showing an optical energy gap of 3.56\xa0eV. The thermal property was evaluated by thermogravimetric analysis. The antibacterial effects of the synthesized iron(III)\xa0complex\xa0have also been examined\xa0in vitro\xa0against clinical bacterial strains: two Gram-positive and four Gram-negative, using the disk diffusion and macro-dilution broth methods. The obtained results show that the Fe(III)\xa0complex\xa0exhibits a marked antibacterial activity, associated with lysozyme and anti-biofilm potential. Furthermore, the results of antifungal studies by the agar well diffusion method demonstrated that our complex possesses higher activity against Candida albicans than the standards Amphotericin B and Fluconazole 25, which showed zone of inhibition diameters of about 19 and 13\xa0mm, respectively, compared to 20\xa0mm given by the new iron complex.