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Öğe 1,3-Bis[(5-aminofuran-2-yl) methyl]3,4,5,6-tetrahydropyrimidin-1-ium hexafluorophosphate(Int Union Crystallography, 2013) Akkurt, Mehmet; Akkoc, Senem; Gok, Yetkin; Tahir, Muhammad NawazThe asymmetric unit of the title salt, C16H21N2O2 (+) center dot PF6 (-), contains half of the whole ion pair, which has crystallographic mirror symmetry. Two F atoms related by the mirror plane are disordered over two sites of equal occupancy. The dihedral angle between the central ring and the furan ring is 59.3 () degrees. In the crystal, the anions and cations are linked through CH center dot center dot center dot F interactions, forming a three- dimensional network.Öğe Benzimidazole-based N-heterocyclic carbene silver complexes as catalysts for the formation of carbonates from carbon dioxide and epoxides(Elsevier, 2022) Nawaz, Zahid; Ullah, Habib; Gurbuz, Nevin; Zafar, Muhammad Naveed; Verpoort, Francis; Tahir, Muhammad Nawaz; Ozdemir, IsmailA series of left-to-right inequivalent 1,3-disubstituted benzimidazolium halide pro-ligands having the general formula [(BNHCCH2OxMe)-B-R][X] (R = 3-Me-Bn, 3,5-Me-2-Bn, 2,4,6-Me-3-Bn, 2,3,5,6-Me-4-Bn, 2,3,4,5,6-Me-5-Bn, 3,4,5-(OMe)(3)-Bn, or 4-Bu-t-Bn; X = Cl, Br) were synthesized by the alkylation of 1-((3-methyloxetan-3-yl)methyl)benzimidazole. The corresponding Ag complexes, ((BNHCCH2OxMe)-B-R) AgX, were prepared following pro-ligand addition to Ag2O. These compounds were characterized using spectroscopic techniques such as FT-IR, NMR spectroscopy, and single-crystal X-ray diffraction. The solid-state structure of ((3-Me-BnBNHCCH2OxMe))AgCl revealed a linear monomer while [((2,4,6-Me3-BnBNHCCH2OxMe))AgCl](2) was found to exist as a dimer with pseudo trigonal planar geometry about each metal center. The synthesized ((BNHCCH2OxMe)-B-R)AgX complexes were found to be efficient for the addition of carbon dioxide to epoxides to yield value-added cyclic carbonates at ambient pressure. Amongst the investigated complexes, the bimetallic complex [((2,4,6-Me3-BnBNHCCH2OxMe))AgCl](2) was found to be the most active for CO2 insertion, exhibiting favorable activity when compared to known NHC complexes.Öğe Catalytic activities in the direct C5 arylation of novel palladium N-heterocyclic carbene complexes containing benzimidazol-2-ylidene nucleus(Elsevier Science Sa, 2014) Akkoc, Senem; Gok, Yetkin; Akkurt, Mehmet; Tahir, Muhammad NawazNew palladium N-heterocyclic carbene (NHC) complexes (1a-e) were synthesized in very good yields by the reaction of 1-phenyl-3-alkylbenzimidazolium salts with Pd(OAc)(2) in dimethyl sulfoxide. These synthesized complexes were fully characterized using elemental analyses, FT-IR, H-1 NMR, C-13 NMR and LC-MS (for 1a, 1c and 1e) spectroscopy data. Also, the molecular structure of the bis[1-phenyl-3-(2methyl-1,4-benzodioxane)benzimidazol-2-ylidene] dibromopalladium(II) complex (1d) was structurally characterized by single crystal X-ray diffraction study. The new Pd-II complexes (1a-e) were tested as catalysts in the direct C5 arylation of 2-n-butylfuran, 2-n-butylthiophene and 2-n-propylthiazole with various aryl bromides at 130 degrees C for 1 h. Also, some experiments were carried out by using aryl chlorides in order to be used for comparison. The results are reported herein. These complexes exhibited quite high catalytic activities under the given conditions. (C) 2014 Elsevier B.V. All rights reserved.Öğe Chlorido[1-phenyl-3-(2,3,5,6-tetramethylbenzyl)benzimidazol-2-ylidene]silver(I)(Int Union Crystallography, 2012) Akkurt, Mehmet; Akkoc, Senem; Gok, Yetkin; Dagdemir, Yilmaz; Tahir, Muhammad NawazIn the title compound, [AgCl(C24H24N2)], the terminal phenyl and tetramethylbenzene rings [which form a dihedral angle of 87.92 (14)degrees] make dihedral angles of 59.59 (11) and 83.19 (12)degrees with respect to the central benzimidazole ring system. The Ag-C and Ag-Cl single-bond lengths are 2.087 (3) and 2.3267 (9)degrees. The C-Ag-Cl bond angle is 172.84 (7)degrees. C-H center dot center dot center dot pi interactions contribute to the stabilization of the crystal structure. A very weak pi-pi stacking interaction between adjacent tetramethylbenzene rings [centroid-centroid distance = 4.0610 (18) angstrom] is also observed.Öğe Design of efficient benzimidazole-derived N- heterocyclic carbene Ag(I) catalysts for aldehyde -amine -alkyne coupling(Elsevier, 2024) Nawaz, Zahid; Gurbuz, Nevin; Zafar, Muhammad Naveed; Tahir, Muhammad Nawaz; Ozdemir, Ismail; Trovitch, Ryan J.A mild catalytic protocol for aldehyde, amine, and alkyne coupling (A3-coupling) allows for the selective synthesis of propargyl amines using 5,6-dimethylbenzimidazole-derived N-heterocyclic carbene (BNHC) silver(I) catalysts. A series of BNHC Ag(I) halide complexes were synthesized and their structures have been elucidated through the use of multinuclear NMR and FT-IR spectroscopy. Furthermore, the pseudo-linear geometry of two different compounds was substantiated by single-crystal X-ray diffraction. Silver-based A3-coupling was achieved for both acyclic and cyclic secondary amines using a diverse set of alkynes to afford propargyl amines with yields of up to 95 %. The present approach is environmentally benign and water is generated as the sole byproduct.Öğe Direct arylation (hetero-coupling) of heteroarenes via unsymmetrical palladium-PEPPSI-NHC type complexes(Pergamon-Elsevier Science Ltd, 2021) Nawaz, Zahid; Gurbuz, Nevin; Zafar, Muhammad Naveed; Tahir, Muhammad Nawaz; Ashfaq, Muhammad; Karci, Huseyin; Ozdemir, IsmailThe growing interest of industry in the field of bi(hetero)arenes compounds, motivated us to synthesize these compounds via homogeneous catalytic route by using Pd PEPPSI-type complexes through direct arylation. In this work, the five new Pd PEPPSI-type complexes bearing NHC spectator ligands were synthesized and characterized by a bunch of spectroscopic techniques. Further confirmations of structural details were provided by a single crystal X-ray diffraction study of one pro-ligand and one complex. All these newly synthesized Pd-carbene complexes were found significantly active as catalysts toward direct arylation of five members heterocyclic compounds such as n-propylthaizole, 2-acetylfurane and 2-acetylthiophene with aryl bromides derivatives. These catalysts give significantly good results within two hours with just 1 mol % catalyst loading.Öğe Imidazole, pyrimidine and diazepine containing heteroaryl-substituted heterocyclic salts as efficient ligand precursors for Mizoroki-Heck coupling reaction: synthesis, structural characterization and catalytic activities(Springer, 2014) Gok, Yetkin; Akkoc, Senem; Akkurt, Mehmet; Tahir, Muhammad NawazThe nine new heteroaryl-substituted imidazolidinium (1a-c), pyrimidinium (2a-c) and diazepinium (3a-c) salts as N-heterocyclic carbene (NHC) precursors were synthesized in good yields and entirely characterized using elemental analyses and conventional spectroscopic methods. In situ formed complexes from heterocyclic salts (1-3), Pd(OAc)(2) and in the presence of KOBu (t) as a base were tested as catalysts for the Mizoroki-Heck coupling reaction in an aqueous media and very high yields were achieved. 1,3-Di(5-methylthiophen-2-ylmethyl)pyrimidinium hexafluorophosphate salt (2b) was structurally characterized by single-crystal X-ray diffraction. In the 2b compound (C16H21N2S2)(+)[PF6](-), the terminal thiophene rings are twisted with a dihedral angle of 72.8(3)A degrees. In the pyrimidine ring, the three successive C atoms between the N atoms are disordered over two positions [occupancy ratio 0.753(12):0.247(12)]. In the crystal, neighboring molecules are linked by C-HaEuro broken vertical bar F hydrogen bonds, running along the b axis.Öğe N- Phenyl- substituted carbene precursors and their silver complexes: synthesis, characterization and antimicrobial activities(Wiley, 2014) Gok, Yetkin; Akkoc, Senem; Albayrak, Sevil; Akkurt, Mehmet; Tahir, Muhammad NawazA series of unsymmetrically substituted N-heterocyclic carbene (NHC) precursors (1a, 1b, 1c, 1d, 1e) were synthesized from the reaction of N-phenylbenzimidazole with various alkyl halides. These compounds were used to synthesize NHC-silver(I) complexes (2a, 2b, 2c, 2d, 2e). The five new 1-phenyl-3-alkylbenzimidazolium salts (1a, 1b, 1c, 1d, 1e) and their NHC-silver complexes (2a, 2b, 2c, 2d, 2e) were characterized by the H-1 NMR, C-13 NMR and FT-IR spectroscopic methods and elemental analysis techniques. Also, the two NHC-silver complexes 2b and 2c were characterized by single-crystal X-ray crystallography, which confirmed the linear C?Ag?Cl arrangements. The antibacterial activities of the NHC precursor and NHC-silver complexes were tested against three Gram-positive bacterial strains (Bacillus subtilis, Listeria monocytogenes and Staphylococcus aureus) and three Gram-negative bacterial strains (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) using the microdilution broth method. The NHC-silver complexes showed higher antibacterial activity than the NHC precursors. In addition, silver complexes 2a, 2b, 2c, 2d showed high antibacterial activity against the Gram-positive bacteria L. monocytogenes and S. aureus compared to the standard, tetracycline. Copyright (c) 2014 John Wiley & Sons, Ltd.Öğe A novel ditopic ring-expanded N-heterocyclic carbene ligand-assisted Suzuki-Miyaura coupling reaction in aqueous media(Pergamon-Elsevier Science Ltd, 2017) Karaca, Emine Ozge; Akkoc, Mitat; Tahir, Muhammad Nawaz; Arici, Cengiz; Imik, Fatma; Gurbuz, Nevin; Yasar, SedatA series of seven-membered ditopic ring-expanded N-heterocyclic carbene (dre-NHC) precursors, bearing sterically demanding and electron-rich aryl groups, were synthesised in moderate yields via the reaction of 1,2,4,5-tetrakis(bromomethyl)benzene with the corresponding N,N'-diarylformamidines in the presence of K2CO3 in acetonitrile under an air atmosphere. All new compounds were characterised by HRMS, NMR spectroscopy, and microanalysis, as well as X-ray crystallography for compound lc. The development of an efficient catalytic system for the Suzuki-Miyaura coupling reaction of aryl chlorides with various boronic acids was also investigated using the in situ generated dre-NHC ligands. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Synthesis of N-heterocyclic carbene-palladium-PEPPSI complexes and their catalytic activity in the direct C-H bond activation(Elsevier Science Sa, 2018) Kaloglu, Nazan; Kaloglu, Murat; Tahir, Muhammad Nawaz; Arici, Cengiz; Bruneau, Christian; Doucet, Henri; Dixneuf, Pierre H.A series of benzimidazolium salts having their two nitrogen atoms substituted by bulky groups have been synthesized. The benzimidazolium salts were readily converted into the corresponding palladium-NHC-PEPPSI complexes with general formula [PdBr2(NHC) (Py)], (NHC = N-heterocyclic carbene; PEPPSI = pyridine-enhanced precatalyst preparation, stabilisation, and initiation). The structures of all new compounds were characterized by NMR, IR spectroscopy and microanalysis techniques, which support the proposed structures. The molecular structure of complex 2g was determined by singlecrystal X-ray diffraction study. Next, the palladium-NHC-PEPPSI complexes were used as catalysts in the direct C5-arylation of 1-methylpyrrole-2-carboxaldehyde by aryl halides. These complexes exhibited moderate to high catalytic activities and gave C-H activation selectively at the C5-position of 1methylpyrrole- 2-carboxaldehyde. Both electron-donating and electron-withdrawing substituents were well tolerated with catalytic systems based on these complexes, even non-activated aryl chlorides such as chlorobenzene or 4-chlorotoluene were coupled with pyrrole in moderate yields. (C) 2017 Elsevier B.V. All rights reserved.Öğe Synthesis, characterization and anticancer activity of allyl substituted N-Heterocyclic carbene silver(I) complexes(Elsevier Science Bv, 2019) Sahin, Neslihan; Sahin-Bolukbasi, Serap; Tahir, Muhammad Nawaz; Arici, Cengiz; Cevik, Esranur; Gurbuz, Nevin; Ozdemir, IsmailMetal N-heterocyclic carbene (NHC) complexes have attracted considerable attention in biological fields for their potential applications in cancer and antimicrobial therapies. In this study, four new benzimidazole-based N-heterocyclic carbene salts (la-d) and their silver (I) complexes (2a-d) were synthesized. All new compounds were characterized by elemental analysis, FT-IR, H-1 NMR and, C-13 NMR spectroscopy. Additionally, single crystal structural studies for complex 2d show that the benzene rings (C9-C14) and the central benzimidazole ring system make dihedral angles of 83.58(13)degrees. The Ag-Cl and Ag-C single bond lengths are 2.3267(8) and 2.087(3) angstrom, respectively. The C-Ag-Cl bond angle is 175.20(7)degrees. The prop-1-ene moiety attached at the second N-atom of benzimidazole is disordered at two set of sites with an occupancy ratio of 0.592(6): 0.408(6). There is one intramolecular hydrogen bond interaction between C22A-H22A... N2. The salts and Ag-complexes were further evaluated for their in vitro anticancer activities against DU-145 human prostate cancer cells, MCF-7, MDA-MB-231 human breast cancer cells and L-929 non-cancer cell for 24 h, 48 h and 72 h using the MTT assay. The Ag(I)-NHC complexes (2a-d) showed a dose and time-dependent cytotoxic activity against all cell lines. The IC(50)s for all Ag(I) NHC complexes lower than 1 mu M for 72 h time points on cancer cells. The results showed that complex 2d exhibited the highest activity against all cancer cell lines studied. Further, the complexes had relatively higher cytotoxicity to cancer cells than to non-cancer cell lines. (C) 2018 Elsevier B.V. All rights reserved.
