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Orhan Buyukgungor - One of the best experts on this subject based on the ideXlab platform.
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co ii ni ii and zn ii orotate complexes with n methylimidazole synthesis crystal structures and antimicrobial activities
Polyhedron, 2011Co-Authors: Hakan Erer, Cihan Darcan, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract Three Co(II), Ni(II) and Zn(II) complexes of orotate with the N-methylimidazole ligand were synthesized and characterized by means of elemental and thermal analysis, magnetic susceptibilities, IR, UV–Vis spectroscopic and antimicrobial activity studies. The crystal structures of [Co(HOr)(H2O)2(Nmeim)2]3·H2O (1), [Ni(HOr)(H2O)2(Nmeim)2] (2) and [Zn(HOr)(H2O)(Nmeim)2] (3) were determined by the single crystal X-ray diffraction technique (H3Or = orotic acid and Nmeim = N-methylimidazole). In complexes 1 and 2, the Co(II) and Ni(II) ions have distorted octahedral geometries with two Nmeim, one orotate and two aqua ligands. Complex 3 has a distorted trigonal bipyramidal geometry with two N-methylimidazole, one orotate and one aqua ligands. In the complexes, the orotate is coordinated to the metal(II) ions through the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group as a bidentate ligand. The complexes form a three-dimensional framework by hydrogen bonding, C–H ⋯ π and π ⋯ π stacking interactions. The MIC values of the complexes against selected microorganisms were determined to be in range 300–2400 μg/mL.
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one dimensional coordination polymers of co ii and cd ii squarate with 2 methylimidazole and 4 5 methylimidazole ligands
Polyhedron, 2010Co-Authors: Hakan Erer, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract Two new mixed-ligand coordination polymers, {[Co(μ 1,3 -sq)(H 2 O) 2 (2-Meim) 2 ]·2(2-Meim)} n ( 1 ) and [Cd(μ 1,3 -sq)(H 2 O) 2 (4(5)-Meim) 2 ] n ( 2 ), (sq = squarate, 2-Meim = 2-methylimidazole, 4(5)-Meim = 5-methylimidazole) have been synthesized and structurally characterized by X-ray crystallography. The spectral (IR and UV–Vis) and thermal analyses are also reported. The Co(II) and Cd(II) ions are distorted octahedrally coordinated by four oxygen atoms of two O 1 –O 3 - bridging squarate ligands and two trans- aqua ligands, and by two nitrogen atoms of the trans -imidazole (2-Meim or 4(5)-Meim) ligands. The structures of 1 and 2 consist of one-dimensional chains of μ-1,3-squarato bridged metal(II) complex units. These chains are held together by hydrogen bonding interactions, forming three-dimensional framework.
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synthesis spectroscopic thermal studies antimicrobial activities and crystal structures of co ii ni ii cu ii and zn ii orotate complexes with 2 methylimidazole
Polyhedron, 2009Co-Authors: Hakan Erer, Cihan Darcan, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract The 2-methylimidazole complexes of Co(II), Ni(II), Cu(II) and Zn(II) orotates, mer -[Co(HOr)(H 2 O) 2 (2-meim) 2 ] ( 1 ), mer -[Ni(HOr)(H 2 O) 2 (2-meim) 2 ] ( 2 ), [Cu(HOr)(H 2 O) 2 (2-meim)] ( 3 ) and [Zn(HOr)(H 2 O) 2 (2-meim)] ( 4 ), were synthesized and characterized by elemental analysis, spectral (UV–Vis and FT-IR) methods, thermal analysis (TG, DTG and DTA), magnetic susceptibility, antimicrobial activity studies and single crystal X-ray diffraction technique. The complexes 1 and 2 have distorted octahedral geometries with two monodentate 2-methylimidazole and one bidentate orotate and two aqua ligands. The complexes 3 and 4 have distorted square pyramidal and trigonal bipyramidal geometry, respectively, with one 2-methylimidazole, bidentate orotate and aqua ligands. The orotate coordinated to the metal(II) ions through deprotonated nitrogen atom of pyrimidine ring and oxygen atom of carboxylate group as a bidentate ligand. The antimicrobial activities of 1 and 4 were found to be more active gram (+) than gram (−) and 4 could be use for treatment Staphylococcus aureus .
Hakan Erer - One of the best experts on this subject based on the ideXlab platform.
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co ii ni ii and zn ii orotate complexes with n methylimidazole synthesis crystal structures and antimicrobial activities
Polyhedron, 2011Co-Authors: Hakan Erer, Cihan Darcan, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract Three Co(II), Ni(II) and Zn(II) complexes of orotate with the N-methylimidazole ligand were synthesized and characterized by means of elemental and thermal analysis, magnetic susceptibilities, IR, UV–Vis spectroscopic and antimicrobial activity studies. The crystal structures of [Co(HOr)(H2O)2(Nmeim)2]3·H2O (1), [Ni(HOr)(H2O)2(Nmeim)2] (2) and [Zn(HOr)(H2O)(Nmeim)2] (3) were determined by the single crystal X-ray diffraction technique (H3Or = orotic acid and Nmeim = N-methylimidazole). In complexes 1 and 2, the Co(II) and Ni(II) ions have distorted octahedral geometries with two Nmeim, one orotate and two aqua ligands. Complex 3 has a distorted trigonal bipyramidal geometry with two N-methylimidazole, one orotate and one aqua ligands. In the complexes, the orotate is coordinated to the metal(II) ions through the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group as a bidentate ligand. The complexes form a three-dimensional framework by hydrogen bonding, C–H ⋯ π and π ⋯ π stacking interactions. The MIC values of the complexes against selected microorganisms were determined to be in range 300–2400 μg/mL.
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one dimensional coordination polymers of co ii and cd ii squarate with 2 methylimidazole and 4 5 methylimidazole ligands
Polyhedron, 2010Co-Authors: Hakan Erer, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract Two new mixed-ligand coordination polymers, {[Co(μ 1,3 -sq)(H 2 O) 2 (2-Meim) 2 ]·2(2-Meim)} n ( 1 ) and [Cd(μ 1,3 -sq)(H 2 O) 2 (4(5)-Meim) 2 ] n ( 2 ), (sq = squarate, 2-Meim = 2-methylimidazole, 4(5)-Meim = 5-methylimidazole) have been synthesized and structurally characterized by X-ray crystallography. The spectral (IR and UV–Vis) and thermal analyses are also reported. The Co(II) and Cd(II) ions are distorted octahedrally coordinated by four oxygen atoms of two O 1 –O 3 - bridging squarate ligands and two trans- aqua ligands, and by two nitrogen atoms of the trans -imidazole (2-Meim or 4(5)-Meim) ligands. The structures of 1 and 2 consist of one-dimensional chains of μ-1,3-squarato bridged metal(II) complex units. These chains are held together by hydrogen bonding interactions, forming three-dimensional framework.
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synthesis spectroscopic thermal studies antimicrobial activities and crystal structures of co ii ni ii cu ii and zn ii orotate complexes with 2 methylimidazole
Polyhedron, 2009Co-Authors: Hakan Erer, Cihan Darcan, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract The 2-methylimidazole complexes of Co(II), Ni(II), Cu(II) and Zn(II) orotates, mer -[Co(HOr)(H 2 O) 2 (2-meim) 2 ] ( 1 ), mer -[Ni(HOr)(H 2 O) 2 (2-meim) 2 ] ( 2 ), [Cu(HOr)(H 2 O) 2 (2-meim)] ( 3 ) and [Zn(HOr)(H 2 O) 2 (2-meim)] ( 4 ), were synthesized and characterized by elemental analysis, spectral (UV–Vis and FT-IR) methods, thermal analysis (TG, DTG and DTA), magnetic susceptibility, antimicrobial activity studies and single crystal X-ray diffraction technique. The complexes 1 and 2 have distorted octahedral geometries with two monodentate 2-methylimidazole and one bidentate orotate and two aqua ligands. The complexes 3 and 4 have distorted square pyramidal and trigonal bipyramidal geometry, respectively, with one 2-methylimidazole, bidentate orotate and aqua ligands. The orotate coordinated to the metal(II) ions through deprotonated nitrogen atom of pyrimidine ring and oxygen atom of carboxylate group as a bidentate ligand. The antimicrobial activities of 1 and 4 were found to be more active gram (+) than gram (−) and 4 could be use for treatment Staphylococcus aureus .
Okan Zafer Yesilel - One of the best experts on this subject based on the ideXlab platform.
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co ii ni ii and zn ii orotate complexes with n methylimidazole synthesis crystal structures and antimicrobial activities
Polyhedron, 2011Co-Authors: Hakan Erer, Cihan Darcan, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract Three Co(II), Ni(II) and Zn(II) complexes of orotate with the N-methylimidazole ligand were synthesized and characterized by means of elemental and thermal analysis, magnetic susceptibilities, IR, UV–Vis spectroscopic and antimicrobial activity studies. The crystal structures of [Co(HOr)(H2O)2(Nmeim)2]3·H2O (1), [Ni(HOr)(H2O)2(Nmeim)2] (2) and [Zn(HOr)(H2O)(Nmeim)2] (3) were determined by the single crystal X-ray diffraction technique (H3Or = orotic acid and Nmeim = N-methylimidazole). In complexes 1 and 2, the Co(II) and Ni(II) ions have distorted octahedral geometries with two Nmeim, one orotate and two aqua ligands. Complex 3 has a distorted trigonal bipyramidal geometry with two N-methylimidazole, one orotate and one aqua ligands. In the complexes, the orotate is coordinated to the metal(II) ions through the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group as a bidentate ligand. The complexes form a three-dimensional framework by hydrogen bonding, C–H ⋯ π and π ⋯ π stacking interactions. The MIC values of the complexes against selected microorganisms were determined to be in range 300–2400 μg/mL.
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one dimensional coordination polymers of co ii and cd ii squarate with 2 methylimidazole and 4 5 methylimidazole ligands
Polyhedron, 2010Co-Authors: Hakan Erer, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract Two new mixed-ligand coordination polymers, {[Co(μ 1,3 -sq)(H 2 O) 2 (2-Meim) 2 ]·2(2-Meim)} n ( 1 ) and [Cd(μ 1,3 -sq)(H 2 O) 2 (4(5)-Meim) 2 ] n ( 2 ), (sq = squarate, 2-Meim = 2-methylimidazole, 4(5)-Meim = 5-methylimidazole) have been synthesized and structurally characterized by X-ray crystallography. The spectral (IR and UV–Vis) and thermal analyses are also reported. The Co(II) and Cd(II) ions are distorted octahedrally coordinated by four oxygen atoms of two O 1 –O 3 - bridging squarate ligands and two trans- aqua ligands, and by two nitrogen atoms of the trans -imidazole (2-Meim or 4(5)-Meim) ligands. The structures of 1 and 2 consist of one-dimensional chains of μ-1,3-squarato bridged metal(II) complex units. These chains are held together by hydrogen bonding interactions, forming three-dimensional framework.
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synthesis spectroscopic thermal studies antimicrobial activities and crystal structures of co ii ni ii cu ii and zn ii orotate complexes with 2 methylimidazole
Polyhedron, 2009Co-Authors: Hakan Erer, Cihan Darcan, Okan Zafer Yesilel, Orhan BuyukgungorAbstract:Abstract The 2-methylimidazole complexes of Co(II), Ni(II), Cu(II) and Zn(II) orotates, mer -[Co(HOr)(H 2 O) 2 (2-meim) 2 ] ( 1 ), mer -[Ni(HOr)(H 2 O) 2 (2-meim) 2 ] ( 2 ), [Cu(HOr)(H 2 O) 2 (2-meim)] ( 3 ) and [Zn(HOr)(H 2 O) 2 (2-meim)] ( 4 ), were synthesized and characterized by elemental analysis, spectral (UV–Vis and FT-IR) methods, thermal analysis (TG, DTG and DTA), magnetic susceptibility, antimicrobial activity studies and single crystal X-ray diffraction technique. The complexes 1 and 2 have distorted octahedral geometries with two monodentate 2-methylimidazole and one bidentate orotate and two aqua ligands. The complexes 3 and 4 have distorted square pyramidal and trigonal bipyramidal geometry, respectively, with one 2-methylimidazole, bidentate orotate and aqua ligands. The orotate coordinated to the metal(II) ions through deprotonated nitrogen atom of pyrimidine ring and oxygen atom of carboxylate group as a bidentate ligand. The antimicrobial activities of 1 and 4 were found to be more active gram (+) than gram (−) and 4 could be use for treatment Staphylococcus aureus .
M. A. Ferreira - One of the best experts on this subject based on the ideXlab platform.
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gas chromatographic mass spectrometric quantification of 4 5 methylimidazole in roasted coffee after ion pair extraction
Journal of Chromatography A, 2002Co-Authors: Susana Casal, M B P P Oliveira, José O. Fernandes, M. A. FerreiraAbstract:Abstract A GC–MS method is described for quantification of 4-(5-)methylimidazole (4MI) in coffee. Although tested, GC–flame ionization detection proved inadequate for this purpose due to the complexity of the coffee matrix. The developed method was based on ion-pair extraction with bis-2-ethylhexylphosphate and derivatization with isobutylchloroformate. Quantification was carried out by the standard addition method using 2-ethylimidazole as internal standard. Reproducibility data from the complete procedure are presented. Mean recoveries were higher than 98%. The method was applied to green and roasted coffee samples from the two most important varieties, arabica and robusta, and to commercial “torrefacto” coffee blends. 4MI was not detected in the green coffee samples analysed and ranged from 0.307 to 1.241 mg/kg in roasted samples.
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gas chromatographic mass spectrometric determination of 4 5 methylimidazole in ammonia caramel colour using ion pair extraction and derivatization with isobutylchloroformate
Journal of Chromatography A, 1997Co-Authors: José O. Fernandes, M. A. FerreiraAbstract:Abstract A procedure for the gas chromatographic-mass spectrometric quantification of 4-(5-)methylimidazole in ammonia caramel colours by using isobutylchloroformate as dervitizing reagent has been developed. The use of this reagent coupled to a previous ion-pair extraction of the compound with Bis-2-ethylhexylphosphate enabled routine determination of 4-(5) methylimidazole with several advantages compared to others methods previously described. Examples of the analysis of some samples are presented as well as data on linearity, recovery and repeatability. Under the adopted conditions the limit of detection and the limit of quantification were 0.250 mg kg −1 and 1 mg kg −1 , respectively.
José O. Fernandes - One of the best experts on this subject based on the ideXlab platform.
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assessment of 4 5 methylimidazole in soft drinks and dark beer
Journal of Food Composition and Analysis, 2011Co-Authors: Sara C Cunha, Ana Isabel Barrado, Miguel A Faria, José O. FernandesAbstract:A B S T R A C T A faster and more robust version of a previously developed method based on ion-pair extraction, acylation with isobutylchloroformate and gas chromatography–mass spectrometry (GC–MS) analysis for determination of 4-(5-)methylimidazole (4-MeI) in soft drinks and dark beer is proposed. The performance of the method was evaluated in terms of linearity (r always > 0.998); recovery (90–101%, 3 levels); and precision (3–8%, 3 levels, n = 6). Limits of detection and quantification in the matrices studied were 0.60 mg/L and 2.2 mg/L, respectively. The optimized method was applied to a wide variety of soft drinks (brand name and generic colas, uncarbonated flavor and energy drinks) and dark beers (lager, ales trappist, ales-stout, weissbier). Overall, soft drinks presented higher amounts of 4-MeI (ranging from 37 to 613 mg/L) than those found in the dark beers (ranging from 3 to 424 mg/L), with colas presenting the highest levels. When the different colas analyzed were compared, the 4-MeI levels in generic colas were generally higher than those in brand-name colas. 4-MeI was found in only one of eight energy drinks studied. Based on available consumption patterns, consumer exposure to the maximum 4MeI given by the soft drinks was 2.3 and 5.7 mg/kg body weight/day, in Europe and the United States, respectively.
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gas chromatographic mass spectrometric quantification of 4 5 methylimidazole in roasted coffee after ion pair extraction
Journal of Chromatography A, 2002Co-Authors: Susana Casal, M B P P Oliveira, José O. Fernandes, M. A. FerreiraAbstract:Abstract A GC–MS method is described for quantification of 4-(5-)methylimidazole (4MI) in coffee. Although tested, GC–flame ionization detection proved inadequate for this purpose due to the complexity of the coffee matrix. The developed method was based on ion-pair extraction with bis-2-ethylhexylphosphate and derivatization with isobutylchloroformate. Quantification was carried out by the standard addition method using 2-ethylimidazole as internal standard. Reproducibility data from the complete procedure are presented. Mean recoveries were higher than 98%. The method was applied to green and roasted coffee samples from the two most important varieties, arabica and robusta, and to commercial “torrefacto” coffee blends. 4MI was not detected in the green coffee samples analysed and ranged from 0.307 to 1.241 mg/kg in roasted samples.
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gas chromatographic mass spectrometric determination of 4 5 methylimidazole in ammonia caramel colour using ion pair extraction and derivatization with isobutylchloroformate
Journal of Chromatography A, 1997Co-Authors: José O. Fernandes, M. A. FerreiraAbstract:Abstract A procedure for the gas chromatographic-mass spectrometric quantification of 4-(5-)methylimidazole in ammonia caramel colours by using isobutylchloroformate as dervitizing reagent has been developed. The use of this reagent coupled to a previous ion-pair extraction of the compound with Bis-2-ethylhexylphosphate enabled routine determination of 4-(5) methylimidazole with several advantages compared to others methods previously described. Examples of the analysis of some samples are presented as well as data on linearity, recovery and repeatability. Under the adopted conditions the limit of detection and the limit of quantification were 0.250 mg kg −1 and 1 mg kg −1 , respectively.
