Investigation of Raman,FT-IR,EPR spectra and antimicrobial activity of 2-(5-H/Me/Cl-1<Emphasis Type="BoldItalic">H</Emphasis>-benzimidazol-2-yl)-phenol ligands and their Fe(NO<Subscript>3</Subscript>)<Subscript>3</Subscript> complexes

2-(5-H/Me/Cl-1H-benzimidazol-2-yl)-phenol ligands form 1:1 electrolytes, 5-coordinate monometallic complexes with iron(III) nitrate. The geometry of the [Fe(L)(OH)(H₂O)₂](NO₃) complexes was derived from theoretical calculation in DGauss/DFT level (DZVP basis set) on CACHE. In all of the complexes the ligands are bidentate, via one imine nitrogen atom and phenolate oxygen atom. The coordination is completed with a hydroxide ion, and two water molecules, adopting a distorted square pyramidal geometry. The structures of the compounds were confirmed on the basis of elemental analysis, molar conductivity, magnetic moment, FT-Raman, FT-IR (mid-IR, far-IR), EPR and u.v.–vis. The antimicrobial activities of the free ligands, their hydrochloride salts, and the complexes were evaluated using the disk diffusion method in dimethyl sulfoxide (DMSO) as well as the minimal inhibitory concentration (MIC) dilution method, against nine bacteria and the results are compared with several known antibiotic agents. Antifungal activities were reported for Candida albicans, Kluyveromyces fragilis, Rhodotorula rubra, Debaryomyces hansenii, Hanseniaspora guilliermondii, and the results were referenced against nystatin, ketaconazole, and clotrimazole antifungal agents. In most cases, the compounds tested showed broad-spectrum (Gram⁺ & Gram⁻ bacteria) activities that were either more active or as potent as the references.     

1,2-Bis-(2-benzimidazolyl)-1,2-ethanediol and 1,4-bis-(2-benzimidazolyl)-1,2,3,4-butanetetraol PdCl2 complexes

The 1,2-bis-(2-benzimidazolyl)-1,2-ethanediol (EH₂) and 1,4-bis-(2-benzimidazolyl)-1,2,3,4-butanetetraol (TH₄) ligands form 4-coordinate mono- and bi-metallic complexes with PdCl₂, respectively. In Pd(EH₂)Cl₂ the ligand acts as a bidentate through two of the nitrogen atoms. On the other hand, in Pd₂(TH₄)Cl₄ the ligand coordinates to two palladium atoms through both bis-benzimidazole nitrogen atoms and two oxygen atoms of the hydroxy groups, forming two different isomers. The complexes were characterised by analytical data, magnetic susceptibility, molar conductivity, and also by i.r., ¹H- and ¹³C-n.m.r. spectra.     

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.