Aydin Tavman

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.

Antimicrobial activity of FeIII, CuII, AgI, ZnII and HgII complexes of 2-(2-hydroxy-5-bromo/nitro-phenyl)-1H- and 2-(2-hydroxyphenyl)-5-methyl/chloro/nitro-1H-benzimidazoles.

Antimicrobial activity of 2-(2-hydroxyphenyl)-5-R5-1H-benzimidazoles, 2-(2-hydroxy-5-R5′-phenyl)-1H-benzimidazoles and their FeIII, CuII, AgI, ZnII and HgII nitrate complexes was tested towardStaphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, andProteus mirabilis. Antifungal activity was tested againstCandida albicans. Benzimidazole benzene ring substituents increase the antimicrobial activity, phenol ring substituents decrease it. The ligands show an antibacterial effect against onlyS. aureus whereas AgI and HgII complexes of the ligands have a higher activity with respect to the other complexes to all the bacteria. On the other hand, FeIII complexes show a considerable activity againstS. aureus andS. epidermidis.

Antimicrobial activity of some 2- and 3-pyridinyl-1H-benzimidazoles and their FeIII, CuII, ZnII, and AgI complexes

Abstract2-(2-Pyridinyl)-(LI), 2-(6-methyl-2-pyridinyl)-(LII), 2-(6-methyl-2-pyridinyl)-5-methyl-(LIII), 2-(3-pyridinyl)- (LIV), 2-(3-pyridinyl)-5-methyl-1H-benzimidazoles (LV) and their complexes with Fe(NO3)3, Cu(NO3)2, Zn(NO3)2, and AgNO3 were synthesized and antibacterial activity of the compounds was tested towardStaphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Proteus mirabilis and antifungal activity againstCandida albicans. The methyl groups ofLIII increase the antimicrobial activity. The AgI complexes have considerable activity toward the microorganisms. Some ZnII complexes show an antimicrobial effect againstS. aureus andS. flexneri, although the ligands themselves have no effect. CuII complexes have a considerable antibacterial effect toS. aureus andS. epidermidis.

Synthesis, Characterization and Antimicrobial Activity of d8-10 MetalComplexes of some 2-Substituted-1H-Benzimidazoles

The metal complexes of nine 2-substituted-1H-benzimidazoles (I-IX) with Ni(II), Pd(II), Cu(II), Ag(I), Zn(II) salts were synthesized. The compounds were characterized by melting point, analytical data, IR spectroscopy and magnetic susceptibility. The antimicrobial activity of the compounds was determined by the disk diffusion method in Mueller-Hinton Agar on Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739, Klebsiella pneumoniae ATCC 4352, Pseudomonas aeruginosa ATCC 1539, Salmonella typhi, Shigella flexneri, Proteus mirabilis, Candida albicans ATCC 10231. Cu(II)and Ag(I)complexes of II, III and IV showed considerable activity against S. aureus, S. epidermidis, Ps. aeruginosa, S. typhi, Sh. flexneri and C. albicans microorganisms, the ligands themselves having no effect.

Spectral characterization and antimicrobial activity of 2-(5-chloro/nitro-1H-benzimidazol-2-yl)-4-bromo/nitro-phenols and their zinc(II) complexes.

2-(5-Chloro/nitro-1H-benzimidazol-2-yl)-4-bromo/nitro-phenols (HL(x); x=1-4) and their complexes with zinc(II)nitrate have been synthesized and characterized. In the tetrahedral mononuclear complexes, the ligands are bidentate, via the imine nitrogen and the phenolate oxygen atoms. The structures of the complexes were confirmed on the basis of elemental analysis, molar conductivity, TGA, FT-IR, NMR, mass and UV-vis spectroscopy. The optimized geometry of the complexes was derived from theoretical calculation in DGauss/DFT level on CACHE program. From theoretical calculations it was found that bromo derivatives of the ligands (HL(1) and HL(3)) have higher stability than the other ligands and similarly, their Zn(II) complexes have higher stability than the other complexes. The antimicrobial activities of the compounds were evaluated using the disk diffusion method against six bacteria and Candida albicans. All of the complexes exhibited selective antibacterial activity on Staphylococcus epidermidis. HL(3) and [Zn(L(1))(2)].H(2)O are more active than Ciprofloxazin and, [Zn(L(2))(2)] has antibacterial activity as potent as Ciprofloxazin against S. epidermidis.

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°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.

Antimicrobial activity of 1,2-bis-[2-(5-R)-1H-benzimidazolyl]-1,2-ethanediols, 1,4-bis-[2-(5-R)-1H-benzimidazolyl]-1,2,3,4-butanetetraols and their FeIII, CuII, and AgI complexes

Abstract1,2-Bis-[2-(5-H/Me/Cl/NO2)-1H-benzimidazolyl]-1,2-ethanediols (L1–L4), 1,4-Bis-[2-(5-H/Me/Cl)-1H-benzimidazolyl]-1,2,3,4-butanetetraols (L5–L7) and their complexes with FeCl3, CuCl2, and AgNO3 were synthesized; antibacterial activity of the compounds was determined towardStaphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Proteus mirabilis, and antifungal activity againstCandida albicans. The AgI complexes have considerable activity toward the microorganisms. Some AgI complexes show higher activity towardS. epidermidis than AgNO3 and cefuroxime. Cu(L3)Cl2 and Fe(L3)Cl3 show an antifungal effect onC. albicans butL3 itself has no activity.

Studies of Metal Complexes of 2-(2-Pyridinyl)-, 2-(6-Methyl-2-Pyridinyl)-, 2(3Pyridinyl)-1H-Benzimidazoles with Some D8–10 Ions

Abstract 2-R-lH-Benzimidazoles [L1, R = 2-pyridinyl; L2, R = 6-methyl-2-pyridinyl; L3, R = 3-pyridinyl] and their complexes with Ni(II), Pd(II), Zn(II), Cd(II), Hg(II) chloride were prepared. The complexes, having 1:1 and 1:2 metal:ligand ratios, were characterized by elemental analyses, magnetic susceptibility and molar conductance measurements, IR and 1H NMR spectroscopy. The Ni(II) complexes are paramagnetic. The metal:ligand ratio are 1:1 in the Pd(II) and Hg(II) complexes of the ligands, and these complexes are non-ionic. In the IR spectra the band character and vibratioual frequencies of the groups participating in coordination changed on complexation. In the 1H NMR spectra, considerable changes were found in the chemical shifts of protons neighboring to the coordinated nitrogen atoms. The ligands L1 and L2 give chelates easily with the metal ions, but L3 does not.

Spectral characterization and antibacterial effect of 2-methyl-6-(5-H-Me-Cl-NO 2-1H-benzimidazol-2-yl)-phenols and some transition metal complexes

Abstract2-Methyl-6-(5-H-methyl-chloro-nitro-1H-benzimidazol-2-yl)-phenols( HLx:x= 1-4)ligands and HL1 complexes with Fe(NO3)3, Cu(NO3)2, AgNO3, Zn(NO3)2 have been synthesized and characterized. The structures of the compounds were confirmed on the basis of elemental analysis, molar conductivity, magnetic moment, FT-IR, 1H-and 13C-NMR. Antibacterial activity of the free ligands, their hydrochloride salts and the complexes were evaluated using the disk diffusion method in dimethyl sulfoxide as well as the minimum inhibitory concentration dilution method, against nine bacteria. While HL1 ligand has not any activity, it’s Ag(I) complex show antibacterial effect toward almost to all the bacteria. Zn(II) complex has antibacterial effect on especially K. pneumoniae, S. epidermidis and S. aureus bacteria.

ACIDITY OF SOME 2-SUBSTITUTED-1HBENZIMIDAZOLES AND THEIR AFFINITY TOWARDS Cu(II) ION

369 INTRODUCTION 370 EXPERIMENTAL 372 Materials and methods 372 Preparation of the 2-substituted-lH-benzimidazole derivatives 372 Potentiometrie titrations 374 RESULTS AND DISCUSSION 376 Solubility of the ligands 376 Protonation constants of the ligands 376 Formation constants of Cu(II) complexes with I-XXVIII 378 REFERENCES 379