Yunus Bekdemir

Experimental and ab initio computational studies on 4-(1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline

The title molecule, 4-(1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline (C15H15N3), was prepared and characterised by 1H-NMR, 13C-NMR, IR and single-crystal X-ray diffraction. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H- and 13C-NMR chemical shift values of the title compound in the ground state have been calculated using the Hartree–Fock (HF) and density functional theory (DFT) methods with 6–31G(d) basis sets, and compared with the experimental data. The calculated results show that the optimised geometries can well reproduce the crystal structural parameters and the theoretical vibrational frequencies, and 1H- and 13C-NMR chemical shift values show good agreement with experimental data. To determine conformational flexibility, the molecular energy profile of the title compound was obtained by semi-empirical (AM1) calculations with respect to the selected torsion angle, which was varied from −180° to +180° in steps of 5°. The energetic behaviour of the title compound in solvent media was examined using the B3LYP method with the 6–31G(d) basis set by applying the Onsager and the Polarizable Continuum Model (PCM). In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and thermodynamic properties of the title compound were investigated using theoretical calculations.

Antimicrobial activity of some sulfonamide derivatives on clinical isolates of Staphylococus aureus

BackgroundStaphylococcus aureus is a non-motile, gram positive, non-sporforming, facultative anaerobic microorganism. It is one of the important bacteria as a potential pathogen specifically for nosocomial infections. The sulfonamide derivative medicines are preferred to cure infection caused by S. aureus due to methicillin resistance.MethodsAntimicrobial activity of four sulfonamide derivatives have been investigated against 50 clinical isolates of S. aureus and tested by using MIC and disc diffusion methods. 50 clinical isolate which collected from specimens of patients who are given medical treatment in Ondokuz Mayis University Medical School Hospital. A control strain of S. aureus ATCC 29213 was also tested.ResultsThe strongest inhibition was observed in the cases of I [N-(2-hydroxy-4-nitro-phenyl)-4-methyl-benzensulfonamid], and II [N-(2-hydroxy-5-nitro-phenyl)-4-methyl-benzensulfonamid] against S. aureus. Compound I [N-(2-hydroxy-4-nitro-phenyl)-4-methyl-benzensulfonamid] showed higher effect on 21 S. aureus MRSAisolates than oxacillin antibiotic. Introducing an electron withdrawing on the ring increased the antimicrobial activity remarkably.ConclusionThis study may help to suggest an alternative possible leading compound for development of new antimicrobial agents against MRSA and MSSA resistant S. aureus. It was also shown here that that clinical isolates of 50 S. aureus have various resistance patterns against to four sulfonamide derivatives. It may also be emphasized here that in vitro antimicrobial susceptibility testing results for S. aureus need standardization with further studies and it should also have a correlation with in vivo therapeutic response experiments.

Structural, spectroscopic and EPR studies of tetraethylammonium tetramethylammonium tetrabomocuprate (II) complex

Abstract The tetraethylammonium tetramethylammonium tetrabromocuprate(II), (hereafter, [(TEA)(TMA)CuBr4]) [(C2H5)4N][(CH3)4N][CuBr4], complex was synthesized and characterized by spectroscopic (IR), structural (XRD) and electron paramagnetic resonance (EPR) technique. The compound contains four isolated and discrete moieties, i.e. two independent [(CH3)4N]+ cations, with one on a -4 axis and the other with the central N atom on a 2z axis, one [(C2H5)4N]]+ cation, on a mirror plane and in a trans conformation, and one distorted tetrahedral [CuBr4]2– anion on another mirror plane. The electron paramagnetic resonance spectra of [(TEA)(TMA)CuBr4] single crystals and powder were investigated in the temperature range from 300 to 5 K. The observed values from the line width and g tensors were found to be temperature dependent. The temperature dependence of Cu(II) complex with EPR spectra values were also discussed in terms of dynamic Jahn-Teller effect.

Microwave Assisted Solvent-Free Synthesis of Some Imine Derivatives

Some imine derivatives (1a–7d) were synthesized using a rapid and an environmentally friendly method with reaction of aromatic aldehydes (a–d) and aromatic amines (1–7) (in 1 : 1 molar ratio) in the presence of -ethoxyethanol as a wetting reagent (2 drops) under solvent-free conditions using microwave heating.

Spectrophotometric flow-injection analysis of mercury(II) in pharmaceuticals with p-nitrobenzoxosulfamate

A new, simple and rapid spectrophotometric FI method for the accurate and precise determination of Hg(II) in pharmaceutical preparations has been developed. The method is based on the measuring the decrease of absorbance intensity of p-nitrobenzoxosulfamate (NBS) due to the complexation with Hg(II). The absorption peak of the NBS, which is decreased linearly by addition of Hg(II), occurs at 430 nm in 2x10(-4) moll(-1) HNO(3) as a carrier solution. Optimization of chemical and FI variables has been made. A micro column consisting of several packing materials applied instead of reaction coil was also investigated. A background level of Fe(III) maintained in reagent carrier solution with NBS was found useful for sensitivity and selectivity. Under the optimized conditions, the sampling rate was over 100 h(-1), the calibration curve obtained were linear over the range 1-10 mugml(-1), the detection limit was lower than 0.2 mugml(-1) for a 20 mul injection volume, and the precision [S(r)=1% at 2 mugml(-1) Hg(II) (n=10)] was found quite satisfactory. Application of the method to the analysis of Hg(II) in pharmaceutical preparations resulted a good agreement between the expected and found values.

Evaluation of the effect of food and beverages on enamel and restorative materials by SEM and Fourier transform infrared spectroscopy

Objectives To examine different types of restorative materials used in children as well as primary and permanent teeth enamel when affected by erosive foods. Materials and Method Buttermilk, fruit yoghurt, Coca‐cola, fruit juice, Filtek Z‐250, Dyract Extra, Fuji II LC, and Fuji IX and tooth enamel were used. Measurements were performed on 1‐day, 1‐week, 1‐month, 3‐month, 6‐month time periods by using ATR‐FTIR technique and surface of the specimens were examined with SEM. Results Permanent tooth showed the least change among human tooth samples when compared to restorative materials. Among filler materials, the most change was observed in Fuji IX. In terms of beverages the most changes on absorption peaks obtained from spectra were seen on the samples held in Coca‐Cola and orange‐juice. Conclusion The exposure of human enamel and restorative materials to acidic drinks may accelerate the degradation process and so reduce the life time of filler materials at equivalent integral exposure times longer than three months. Clinical Relevance Erosive foods and drinks having acidic potential destroy not only tooth enamel but also restorative materials. Microsc. Res. Tech. 77:79–90, 2014.

Acid-catalysed hydrolysis of some aromatic cyclic sulfamates

The acid catalysed hydrolysis of some cyclic sulfamates, X-3-(p-tolylsulfonyl)-1,2,3-benzoxathiazole 2,2-dioxides ( 1a , X = Me; 1b , X = H; 1c , X = Cl; 1d , X = NO 2 ) have been studied in concentrated aqueous sulfuric and perchloric acid solutions. Analysis of the data by the Excess Acidity Method, activation parameters, substituent, solvent deuterium isotope effect and order of the catalytic effects of the acids are all in agreement with an A-1 mechanism in the studied range.

Bis(p-nitrobenzoxasulfamato) Complexes of Cadmium(II) and Mercury(II) Synthesis, Spectra, and X-Ray Crystal Structures

The reaction of sodium benzoxasulfamate (nbs) with cad- mium(II) and mercury(II) sulfate in aqueous solution yield the no- vel complexes (Cd(nbs)2(H2O)4) (1) and (Hg(nbs)2(H2O)3 )( 2), respectively. The complexes were characterized by elemental analy- ses, IR spectroscopy and X-ray crystallography. Complex 1 is monomeric and has an octahedral arrangement in which the N-donor nbs ligands occupy the axial positions, while the water oxygen atoms form the equatorial plane. Complex 2 is polymeric and shows a pentagonal bipyramidal arrangement achieved by the bridging of the HgN2O3 units through the weak interaction of the

4-Chloro-2-[(4-chloro­benzyl­idene)amino]­phenol

In the title Schiff base compound, C13H9Cl2NO, the molecule displays an E conformation about the imine C=N double bond, with a dihedral angle of 8.09 (11)° between the two benzene rings. In the crystal, molecules are linked by a single O—H⋯O hydrogen bond, giving one-dimensional chains which extend along (100).

SIMPLE, MILD, AND HIGHLY EFFICIENT SYNTHESIS OF 2-SUBSTITUTED BENZIMIDAZOLES AND BIS- BENZIMIDAZOLES

A new convenient method for preparation of 2-substituted benzimidazoles and bis-benzimidazoles is presented. In this method, o-phenylenediamines were condensed with bisulfite adducts of various aldehydes and di-aldehydes under neat conditions by microwave heating. The results were also compared with results of synthesis by conventional heating under reflux. Structures of the products were confirmed by infrared, 1H- and 13C-NMR spectroscopy. Short reaction times, good yields, easy purification of products, and mild reaction conditions are the main advantages of this method.