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    Benzimidazol-2-ylidene Silver Complexes: Synthesis, Characterization, Antimicrobial and Antibiofilm Activities, Molecular Docking and Theoretical Investigations
    (Mdpi, 2023) Tutar, Ugur; Celik, Cem; Ustuen, Elvan; Ozdemir, Namik; Sahin, Neslihan; Semeril, David; Gurbuz, Nevin
    Five silver(I) complexes, namely chloro[1-methallyl-3-benzyl)benzimidazol-2-ylidene] silver (6), chloro[1-methallyl-3-(2,3,5,6-tetramethylbenzyl)benzimidazol-2-ylidene]silver (7), chloro[1-methallyl-3-(3,4,5-trimethoxylbenzyl)benzimidazol-2-ylidene]silver (8), chloro[1-methallyl- 3-(naphthylmethyl)benzimidazol-2-ylidene]silver (9), and chloro [1-methallyl-3-(anthracen-9-yl- methyl)benzimidazol-2-ylidene]silver (10), were prepared starting from their corresponding benzimidazolium salts and silver oxide in 71-81% yields. A single-crystal X-ray structure of 7 was determined. These five Ag-NHC complexes were evaluated for their antimicrobial and biofilm formation inhibition properties. Complex 10 exhibited high antimicrobial activities comparable to those obtained with standard drugs such as Fluconazole in contact with Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Acinetobacter baumannii, and Candida albicans. The latter complex has been shown to be very efficient in antibiofilm activity, with 92.9% biofilm inhibition at 1.9 mu g/mL on Escherichia coli. Additionally, the molecules were optimized with DFT-based computational methods for obtaining insight into the structure/reactivity relations through the relative energies of the frontier orbitals. The optimized molecules were also analyzed by molecular docking method against DNA gyrase of Escherichia coli and CYP51 from Candida albicans.
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    Copper-Catalysed Allylic Substitution Using 2,8,14,20-Tetrapentylresorcinarenyl-Substituted Imidazolium Salts
    (Wiley-V C H Verlag Gmbh, 2015) Kaloglu, Murat; Sahin, Neslihan; Semeril, David; Brenner, Eric; Matt, Dominique; Ozdemir, Ismail; Kaya, Cemal
    Unsymmetrical imidazolium salts, each having one nitrogen atom (N1) substituted by a cavity-shaped TPR group (TPR = 2,8,14,20-tetrapentylresorcinaren-5-yl), were tested in situ as proligands for the copper-catalysed allylic arylation of cinnamyl bromide with arylmagnesium halides. The catalytic systems produced mixtures of linear (l) and branched (b) arylated compounds in variable proportions, with the b/l ratio being the highest (78:22) for the most crowded imidazolium salt used, namely that in which the second nitrogen atom (N2) was substituted by a mesityl group. An N-heterocyclic carbene complex obtained from one of the imidazolium salts was characterised by an X-ray diffraction study.
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    Design, synthesis, antimicrobial activity and molecular docking study of cationic bis-benzimidazole-silver(I) complexes
    (Wiley-V C H Verlag Gmbh, 2023) Ustun, Elvan; Sahin, Neslihan; Ozdemir, Ilknur; Gunal, Selami; Gurbuez, Nevin; Ozdemir, Ismail; Semeril, David
    Two series of bis(1-alkylbenzimidazole)silver(I) nitrate and bis(1-alkyl-5,6-dimethylbenzimidazole)silver(I) nitrate complexes, in which the alkyl substituent is either an allyl, a 2-methylallyl, an isopropyl or a 3-methyloxetan-3-yl-methyl chain, were synthesized and fully characterized. The eight N-coordinated silver(I) complexes were screened for both antimicrobial activities against Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii) and Gram-positive (Staphylococcus aureus, Staphylococcus aureus MRSA, and Enterococcus faecalis) bacteria and antifungal activities against Candida albicans and Candida glabrata strains. Moderate minimal inhibitory concentrations (MIC) of 0.087 & mu;mol/mL were found when the Gram-negative and Gram-positive bacteria were treated with the silver complexes. Nevertheless, MIC values of 0.011 & mu;mol/mL, twice lower than for the well-known fluconazole, against the two fungi were measured. In addition, molecular docking was carried out with the structure of Escherichia coli DNA gyrase and CYP51 from the pathogen Candida glabrata with the eight organometallic complexes, and molecular reactivity descriptors were calculated with the density functional theory-based calculation methods.
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    The Influence of Imidazolylidene Ligands with Bulky Resorcinarenyl Substituents on Catalysts for Suzuki-Miyaura Coupling
    (Wiley-V C H Verlag Gmbh, 2016) Kaloglu, Murat; Semeril, David; Brenner, Eric; Matt, Dominique; Ozdemir, Ismail; Toupet, Loic
    PEPPSI-type imidazolylidene palladium complexes having their carbenic ring N-substituted with an aryl ring and a cavity-shaped unit [25,26,27,28-tetrapropyloxycalix[4]aren-5-yl or 6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]aren-5-yl (TPR)] have been prepared and assessed in Suzuki-Miyaura cross-couplings. Remarkable efficiency in the coupling of aryl chlorides with sterically hindered arylboronic acids was observed for the carbene ligand having its N atoms (N1, N2) substituted by a mesityl and a TPR group, respectively. This good performance possibly arises from strong steric interactions between the pentyl-substituted cavitand unit and the catalytic centre, which favours reductive elimination. Two of the imidazolium salts used for complex synthesis were characterised by X-ray diffraction analysis.
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    Palladium-Catalyzed Cross-Coupling Reaction via C-H Activation of Furanyl and Thiofuranyl Substrates
    (Mdpi, 2024) Sahin, Neslihan; Ozdemir, Ismail; Semeril, David
    The present study explores the potential of four NHC-palladium(II) complexes derived from (Z)- or (E)-styryl-N-alkylbenzimidazolium salts, namely trans-dichloro-[(Z)-1-styryl- 3-benzyl-benzimidazol-2-yliden]pyridine palladium(II) (6), trans-dichloro-[(E)-1-styryl-3-benzyl- benzimidazol-2-yliden]pyridine palladium(II) (7), trans-dichloro-[(Z)-1-styryl-3-(3-fluorobenzyl)- benzimidazol-2-yliden]pyridine palladium(II) (8) and trans-dichloro-[(E)-1-styryl-3- (3-fluorobenzyl)-benzimidazol-2-yliden]pyridine palladium(II) (9), to be use as pre-catalysts for the cross-coupling reactions between furanyl or thiofuranyl derivatives and arylbromides via the C-H activation of the heterocycles. The structures of the four Pd(II) complexes have been elucidated through the use of multinuclear NMR, FT-IR and mass spectroscopy. Furthermore, the cis or trans conformation of the styryl substituents and the geometry of two different compounds was substantiated by single-crystal X-ray diffraction, which was carried out on organometallic species 6, 8 and 9. After the optimization of catalytic conditions, which was carried out with 1 mol% of pre-catalyst with KOAc as a base in dimethylacetamide at 120 degrees C for 3 h, complex 6 proved to be the most effective pre-catalyst agent, with full or quasi full conversions being observed in the cross-coupling of 4-bromoacetophenone with 2-butylfuran, 1-(2-furanyl)-ethanone, furfuryl acetate, furfural, 1-(2-thienyl)-ethanone, thenaldehyde and 2-methylthiophene.
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    Resorcinarene-Functionalised Imidazolium Salts as Ligand Precursors for Palladium-Catalysed SuzukiMiyaura Cross-Couplings
    (Wiley-V C H Verlag Gmbh, 2013) Sahin, Neslihan; Semeril, David; Brenner, Eric; Matt, Dominique; Ozdemir, Ismail; Kaya, Cemal; Toupet, Loic
    Three imidazolium salts based on a rigid resorcinarene platform (13) were synthesised and used as catalyst precursors in the SuzukiMiyaura cross-coupling of aryl halides with phenylboronic acid. In these pro-carbene ligands, the heterocyclic moiety has one N atom connected to a C2 atom of a resorcinolic ring, and the other is substituted by an alkyl group (R=n-propyl, iso-propyl, benzyl). The methinic C atoms of the macrocyclic core are all substituted by a pentyl group. The best catalytic performances were obtained by using an imidazolium/Pd ratio of 1:1. The catalytic systems displayed high activities, which increased in the order R=n-propyl(1)
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    Ruthenium(II)-(p-cymene)-N-Heterocyclic Carbene Complexes for the N-Alkylation of Amine Using the Green Hydrogen Borrowing Methodology
    (Wiley-V C H Verlag Gmbh, 2018) Kaloglu, Murat; Gurbuz, Nevin; Semeril, David; Ozdemir, Ismail
    Six ruthenium(II) complexes with the general molecular formula [RuCl2(NHC)((6)-p-cymene)] (NHC = N-heterocyclic carbene) were synthesized by the transmetalation method from [RuCl2((6)-p-cymene)](2) and silver(I)-NHC complexes. All complexes were fully characterized by analytical and spectral methods (FT-IR, elemental analysis and H-1 and C-13 NMR). The solid-state structure of one of the ruthenium complexes [dichloro-{1-[2-(2-ethoxyphenoxy)ethyl]-3-(3,5-dimethylbenzyl)benzimidazol-2-ylidene}(p-cymene) ruthenium(II)] has been established by single-crystal X-ray diffraction study, which revealed that the ruthenium atom adopt a classical piano-stool coordination geometry. Under the optimised conditions, these ruthenium complexes were found to be efficient catalysts for N-alkylation of aniline with arylmethyl alcohols using the hydrogen borrowing strategy, which is a cost-effective and environmentally attractive reaction for the preparation of N-alkylated amines.
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    Subtle Steric Effects in Nickel-Catalysed Kumada-Tamao-Corriu Cross-Coupling Using Resorcinarenyl-Imidazolium Salts
    (Wiley-V C H Verlag Gmbh, 2013) Sahin, Neslihan; Semeril, David; Brenner, Eric; Matt, Dominique; Ozdemir, Ismail; Kaya, Cemal; Toupet, Loic
    Three resorcinarene-cavitands bearing a 3-R-1-imidazolylium substituent (R = alkyl) grafted to the wider rim of the cavitand (1-3) were assessed in the Kumada-Tamao-Corriu cross-coupling of aryl halides with arylmagnesium halides. Their combination with [Ni(cod)(2)] (cod = 1,5-cyclooctadiene; 1:1 stoichiometry) resulted in highly efficient catalysts, the activities of which varied in the following order: R = n-propyl (1) < isopropyl (2) approximate to benzyl (3). A remarkable turnover frequency of 60400 mol(ArX) mol(Ni)(-1) h(-1) was obtained in the coupling of 2-bromo-6-methoxynaphthalene with PhMgBr (100 degrees C in dioxane, with precursor 2). The high activities of the cavitand derivatives were attributed to steric effects that facilitate the reductive-elimination/product decoordination step. Comparative experiments carried out with a structurally modified resorcinarene, as well as cavity-free imidazolium salts bearing 2-methoxyaryl substituents, suggest that the efficiency of the catalysts mainly relies on steric interactions between the metal and the flexible substituents attached to two methine carbon atoms. These steric interactions are probably reinforced each time the metal binds one of the two oxygen atoms located next to the catalytic centre.
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    Synthesis and use of trans-dichlorido-tetrakis-(N-R-imidazole)nickel(II) complexes in Kumada-Tamao-Corriu cross-coupling reactions
    (Pergamon-Elsevier Science Ltd, 2011) Sahin, Neslihan; El Moll, Hani; Semeril, David; Matt, Dominique; Ozdemir, Ismail; Kaya, Cemal; Toupet, Loic
    Two dichlorido-tetrakis-(N-R-imidazole)nickel(II) complexes (R = 2,6-diisopropylphenyl (1): methyl (2)) have been synthesised. A single crystal X-ray diffraction study was carried out for 1, which revealed a centrosymmetric complex with the nickel centre placed in an octahedral coordination environment. Both complexes showed high activities (TOFs up to 60200 mol(ArBr) mol(Ni)(-1) h(-1)) in Kumada-Tamao-Corriu cross-coupling of arylhalides with arylgrignards. No significant differences in activity were observed between the two complexes. (C) 2011 Elsevier Ltd. All rights reserved.