Browsing by Author "Atli, DD"

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    Dinuclear silver-bis(N-heterocyclic carbene) complexes: Synthesis, catalytic activity in propargylamine formation and computational studies
    Atli, DD; Sen, B
    Preparation of a series of 1,1 '-dialkyl-3,3 '-(2-methylenepropane-1,3-diyl)dibenzimidazolium salts (alkyl = ethyl, propyl, butyl) (2a-2c) and their dinuclear bis(N-heterocyclic carbene) silver complexes (3a-3c) is reported. The silver complexes were synthesized via in situ deprotonation with Ag2O in 67-74% yields. The structural definitions of the synthesized compounds were performed by H-1 NMR, C-13 NMR, elemental analysis, FT-IR and also LC-MSMS techniques (only for 3a-3c). The silver complexes were utilized for three-component coupling reactions of aldehydes, amines and alkynes (A(3)-coupling). It was found that increasing the chain length of the alkyl substituent on the N-heterocyclic carbene ligand led to increase in catalytic performance. 3c showed the highest activity with 81% yield and with TON of 27 for N,N-diethyl-3-phenylprop-2-yn-1-amine formation. Geometry optimization was performed and geometric parameters were calculated for the compounds. The theoretical harmonic vibration frequencies of molecules were computed by DFT/B3LYP methods for their optimized geometries.
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    Air stable N-heterocyclic carbene silver complexes: synthesis, characterization, and antibacterial activity
    Atli, DD; Aksu, D
    A new benzimidazolium salt containing a 2,5-dimethylbenzyl substituent and six N-heterocyclic carbene (NHC) silver complexes were prepared. The complexes were characterized by NMR, FTIR, and LC-MS spectroscopic methods and elemental analyses. They are stable in solution for a week. The antibacterial properties of the Ag(I) complexes against two Gram-positive and two Gram-negative bacteria were investigated. Inhibition zone and minimum inhibitory concentration (MIC) data establish that these NHC-Ag(I) complexes possess antibacterial activities; 2b showed the highest antibacterial activity overall against Gram-positive and Gram-negative bacteria.
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    Synthesis, characterization, and antibacterial properties of novel N-heterocyclic carbene (NHC) precursors and their silver complexes
    Atli, DD; Özbek, HA; Aksu, D
    In this work, a new compound, 1-(3,5-dimethoxybenzyl)-5,6-dimethylbenzimidazole, was prepared by N-alkylation of 5,6-dimethylbenzimidazole with potassium hydroxide and 3,5-dimethoxybenzyl bromide in ethanol. Three 5,6-dimethylbenzimidazolium salts were obtained by quaternisation of 1-(3,5-dimethoxybenzyl)-5,6-dimethylbenzimidazole with 4-cyanobenzyl bromide, 4-tert-butylbenzyl bromide, and bromoethane, respectively. Deprotonation of these with silver oxide afforded NHC silver complexes in good yields. The formation of the compounds was validated by nuclear magnetic resonance, Fourier transform infrared spectroscopy, elemental analysis, and LC-MS/MS (only for the silver complexes) methods. The complexes were found to be stable against air and light by H-1 NMR analysis of their solutions after one week. Experimental studies were carried out on the antibacterial properties of both benzimidazolium salts and NHC silver complexes against pathogenic strains of Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Enterobacter cloacae. Inhibition zone and minimum inhibitory concentration values were determined. On the basis of these data, it was concluded that all the compounds studied were antibacterial against all the bacterial chains tested, particularly Gram-positive bacteria. The MIC values indicate that the coordination of the NHC ligands to the Ag(I) ion leads to an increase in their antibacterial activity. Bromo[1-(3,5-dimethoxybenzyl)-3-(4-tert-butylbenzyl)-5,6-dimethylbenzimidazolin-2-ylidene]silver showed better activity against S. aureus than the standard antibiotic gentamicin. [GRAPHICS] .
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    Synthesis, characterization and catalytic properties of cationic N-heterocyclic carbene silver complexes
    Atli, DD
    Three new dibenzimidazolium salts bridged by 2-methylenepropane-1,3-diyl group were synthesized. Their dinuclear N-heterocyclic carbene Ag(I) complexes were prepared by the reactions of these salts with Ag2O. The structures of the synthesized compounds were defined by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, and LC-MSMS (for complexes) techniques. Stability of the silver complexes was confirmed by 'H NMR spectroscopy. Catalytic activities of Ag(I) compounds were tested for three-component coupling reaction of some aldehydes, amines, and phenylacetylene.
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    Synthesis and catalytic application of cyclopentadienyl nickel(II) N-heterocyclic carbene complexes
    Atli, DD
    A series of ester-functionalized benzimidazolium salts2a-cwere prepared by quaternization of 1-{(ethoxycarbonyl)methyl}benzimidazole (1) with 3,5-dimethylbenzyl bromide, 2,5-dimethylbenzyl chloride and 3-methoxybenzyl chloride, respectively. Refluxing2a-cwith nickelocene in THF yielded the neutral cyclopentadienyl NHC nickel(II) complexes3a-c. Their structures were defined by NMR, IR and elemental analysis techniques. Molecular weights of3a-cwere affirmed by MALDI-TOF mass spectrometry. Catalytic tests of3a-cwere performed in Kumada coupling of some aryl chlorides with phenylmagnesium bromide at 25 degrees C. [GRAPHICS] .
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    Dinuclear N-heterocyclic carbene silver complexes: Synthesis, luminescence and catalytic studies
    Atli, DD; Gülle, S
    A new dibenzimidazole compound (1) and three dibenzimidazolium salts (2a-2c) were prepared. Reactions of these salts with silver(I) oxide in methanol led to dinuclear N-heterocyclic carbene silver complexes (3a-3c). All of the compounds were characterized by H-1 NMR, C-13 NMR and elemental analyses. Molecular weights of the silver complexes were confirmed by MALDI-TOF mass spectrometry. Preliminary catalytic studies using all the silver complexes were performed on three-component coupling reaction of p-formaldehyde, piperidine and phenylacetylene. Complexes 3a and 3c exhibited good catalytic activities under neat conditions. The silver complexes showed luminescence properties in CH3CN at room temperature. (C) 2018 Elsevier B.V. All rights reserved.