Spectral characterization and antimicrobial activity of some transition metal complexes of 2-(5-nitro-1H-benzimidazol-2-yl)-4-bromophenol

ABSTRACT. MnCl2, FeCl3, Ru(DMSO)4Cl2, CoCl2, NiCl2, PdCl2, CuCl2, AgNO3, CdCl2 and HgCl2 complexes of 2-(5-nitro-1H-benzimidazol-2-yl)-4-bromophenol (HL) were synthesized and characterized. The structures of the complexes were confirmed on the basis of elemental analysis, TGA, molar conductivity and magnetic moment measurements, FT-IR, far-IR, FT-Raman, UV-Visible, NMR and fluorescence spectroscopy. According to the analytical and spectral data, the ligand acted as bidentate, via the imine nitrogen and the phenolate oxygen atoms towards to the metal ions except the Ag(I). The complexes were screened for in vitro antibacterial activities against S. aureus, S. epidermidis, E. coli, K. pneumoniae, P. aeruginosa, P. mirabilis and for antifungal activity against C. albicans. Ciprofloxacin and fluconazole were used as reference for antibacterial and antifungal activities of the complexes, respectively. In most cases, the complexes tested showed considerable activity on S. aureus especially, which is a Gram positive bacterium. In addition, the Hg(II) and Ag(I) complexes were found to have superior activity toward all of the microorganisms whereas the Pd(II) and Cd(II) complexes showed considerably antimicrobial effect on S. aureus and C. albicans selectively.               KEY WORDS: Benzimidazole, Bromophenol, Transition metal complexes, Antibacterial, Antifungal Bull. Chem. Soc. Ethiop. 2019, 33(3), 451-466.   DOI: https://dx.doi.org/10.4314/bcse.v33i3.

Removal of fluoride using the adsorbents produced from mining waste

The capability of the use of the adsorbent produced from coal mining wastes for uptaking fluoride from aqueous solutions was investigated. Experiments were carried out as a function of initial concentration, time, and pH. Lagergren equation was used to describe the adsorption rate of fluoride and rate constant was calculated. The effect of kinetic mechanism was also investigated. Both intraparticle diffusion and film diffusion played roles in the adsorption of fluoride. The equilibrium data were fitted to the Langmuir and Freundlich isotherms. The values of Q and k obtained from the Langmuir and Freundlich equations were found to be 15.67 mg/g and 8.55. Data obtained at various pH indicated that the removal of fluoride was favourable at low pH. The optimum pH for fluoride adsorption was found to be 3.5. The capacity of the adsorbent was compared with other adsorbents. The results showed that the capacity of the adsorbents were higher than alum sludge, lignite, bituminous coal, fine coke, spent bleaching earth, lantanum impregnated silica gel, activated alumina

<b>Synthesis, spectral characterizations and antimicrobial activity of some Schiff bases of 4-chloro-2-aminophenol</b>

A series of 4-chloro-2-[(arylmethylidene)amino]phenols (<b>1</b>–<b>11</b>) including methoxy group were synthesized using appropriate synthetic route. The structures of the Schiff bases were characterized by FT-IR, UV-Vis, ESI-MS, ¹H and ¹³C-NMR spectroscopic techniques and analytical methods. A relation is observed between melting points and existence of intramolecular hydrogen bonding. IR spectra of the compounds including and not including hydrogen bonding were compared. The compounds <b>2</b> and <b>4</b> show the characteristic UV bands attributed to the NH-forms. According to the ¹H-NMR spectral data the compound <b>2</b> has the strongest intramolecular hydrogen bonding and the compound <b>6</b> shows two isomeric structure. On the other hand, antibacterial and antifungal activities of the compounds were investigated. Most of the compounds show selective activity toward <i>S. epidermidis</i> and <i>C. albicans</i>

Spectral characterization and antimicrobial activity of Cu(II) and Fe(III) complexes of 2-(5-Cl/NO2-1H-benzimidazol-2-yl)-4-Br/NO2-phenols

The compounds of 2-(5-chloro/nitro-1H-benzimidazol-2-yl)-4-bromo/nitrophenols (HLX : X = 1-4) and their copper(II) nitrate and iron(III) nitrate complexes have been synthesized and characterized. The structures of the complexes were confirmed on the basis of elemental analysis, thermal gravimetric analysis, molar conductivity and magnetic moment measurements, FT-IR, mass, and UV-Vis spectroscopy techniques. The complexes show high-thermal stability with 350 degrees C m.p. In all complexes, the ligands are bidentate via one imine nitrogen and a phenolate oxygen. Cu(II) complexes having 1 : 2 M : L ratio are classified as non-electrolytes, whereas 1 : 1 M : L ratio is observed in Fe(III) complexes except [Fe(L3)2(H2O)2](NO3) 3H2O. The antimicrobial activities of the ligands and the complexes were evaluated using the disc diffusion method in DMSO as well as minimum inhibitory concentration dilution method against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Proteus mirabilis. Antifungal activities were reported for Candida albicans. The complexes [Fe(L3)2(H2O)2](NO3) 3H2O and [Cu(L3)2] 2H2O are more effective against S. epidermidis than ciprofloxacin

Synthesis, Spectral Characterization and Antimicrobial Activity of Some Transition Metal Complexes of 1,3-Bis(1H-benzimidazol-2-yl)-2-oxapropane

1,3-Bis(1H-benzimidazol-2-yl)-2-oxapropane (L) complexes with Fe(NO3)(3), CoCl2, Co(NO3)(2), Ni(NO3)(2), CuCl2, Cu(ClO4)(2), PdCl2, CdI2, Hg(NO3)(2) were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment, TGA, FT-IR, NMR, ESI-MS, fluorescence spectroscopy. Also, the crystal structure of 1,3-bis(1H-benzimidazol-2-yl)-2- oxapropane] dichlorocobalt(II), [Co(L)Cl-2], complex is reported that it has distorted trigonal bipyramidal geometry. Antibacterial activities of the compounds were evaluated using the disk diffusion method against six bacteria and Candida albicans. The Hg(II) complex shows superior activity toward S. epidermidis and E. coli whereas the other complexes are ineffective except the Co(NO3)(2) complex: it showed weak activity toward all of the microorganisms