Yazar "Sahin, Onur" seçeneğine göre listele
Listeleniyor 1 - 20 / 175
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe 1D heteronuclear coordination polymers of hexacyanocobaltate(III) with 2-hydroxymethylpyridine(Pergamon-Elsevier Science Ltd, 2024) Kekec, Seray; Kurkcuoglu, Gunes Suheyla; Yesilel, Okan Zafer; Sahin, OnurThree new hexacyanocobaltate(III) complexes, {[M 2 (hmpy) 4 Co( mu- CN) 4 (CN) 2 ] center dot 2H 2 O} n (M = Cu(II) ( 1 ), Zn(II) ( 2 ) and Cd(II) ( 3 )) were synthesized with 2-hydroxymethylpyridine (hmpy) ligand, and characterized by vibration (FT - IR and Raman) spectral, single crystal X-ray diffraction (SC-XRD) and powder X-ray diffraction (PXRD), thermal and elemental analyses techniques. The crystallographic analyses revealed that cyanide complexes 1 - 3 are infinite one-dimensional coordination polymers. Each M ion is coordinated by two nitrogen and two oxygen atoms from the hmpy ligands and two nitrogen atoms from the cyanide ligands, displaying a distorted octahedral coordination geometry. Similarly, each Co(III) ion is coordinated by six carbon atoms from cyanide ligands to form a distorted octahedral coordination geometry. These complexes form 3D supramolecular networks through O - H & sdot;& sdot;& sdot; O hydrogen bonds and C - H & sdot;& sdot;& sdot; N interactions. Additionally, structural analyses such as metal salts, pH values of the compounds obtained under different conditions were evaluated. A synthesis -structural analyses relation was made from these data.Öğe 3D Polyoxometalate-Functionalized Graphene Quantum Dots with Mono-Metallic and Bi-Metallic Nanoparticles for Application in Direct Methanol Fuel Cells(Electrochemical Soc Inc, 2016) Colak, Alper Tolga; Eren, Tanju; Yola, Mehmet Lutfi; Besli, Erdem; Sahin, Onur; Atar, NecipA fuel cell is an electrochemical cell that converts a source fuel into an electrical current. It generates electricity inside a cell through reactions between a fuel and an oxidant, triggered in the presence of an electrolyte. Fuel cells have been attracting more and more attention in recent decades due to high-energy demands, fossil fuel depletions, and environmental pollution throughoutworld. Afacile and cost-effective catalysts have been developed on polyoxometalate (NaPWO) functionalized graphene quantum dots (GQDs) with several mono-metallic and bi-metallic nanoparticles such as platinum nanoparticles (PtNPs), palladium nanoparticles (PdNPs) and platinum-palladium nanoparticles (Pt-PdNPs). The successful synthesis of nanomaterials and the prepared glassy carbon electrode (GCE) surfaces were confirmed by transmission electron microscope (TEM), X-ray photo electron spectroscopy (XPS), scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS) and X-ray diffraction (XRD) method. According to TEM images, the average particle sizes of PtNPs and PdNPs were found to be approximately 20-30 nm. The Pt-PdNPs/NaPWO/GQDs also exhibited a higher peak current for methanol oxidation than those of comparable PdNPs/NaPWO/GQDs and PtNPs/NaPWO/GQDs, thus providing evidence for its higher electro-catalytic activity. (C) 2016 The Electrochemical Society. All rights reserved.Öğe A cobalt (II) complex with 6-methylpicolinate: Synthesis, characterization, second- and third-order nonlinear optical properties, and DFT calculations(Pergamon-Elsevier Science Ltd, 2016) Alturk, Sumeyye; Avci, Davut; Tamer, Omer; Atalay, Yusuf; Sahin, OnurA cobalt(II) complex of 6-methylpicolinic acid, [Co(6-Mepic)(2)(H2O)(2)]center dot 2H(2)O, was prepared and fully determined by single crystal X-ray crystal structure analysis as well as FT-IR, FT-Raman. UV-vis spectra were recorded within different solvents, to illustrate electronic transitions and molecular charge transfer within complex 1. The coordination sphere of complex 1 is a distorted octahedron according to single crystal X-ray results. Moreover, DFT (density functional theory) calculations with HSEH1PBE/6-311 G(d,p) level were carried out to back up the experimental results, and form base for future work in advanced level. Hyperconjugative interactions, intramolecular charge transfer (ICT), molecular stability and bond strength were researched by the using natural bond orbital (NBO) analysis. X-ray and NBO analysis results demonsrate that O-H center dot center dot center dot O hydrogen bonds between the water molecules and carboxylate oxygen atoms form a 2D supramolecular network, and also adjacent 2D networks connected by C-H center dot center dot center dot pi and pi center dot center dot center dot pi interactions to form a 3D supramolecular network. Additionally, the second- and third-order nonlinear optical parameters of complex 1 were computed at DFT/FISEH1PBE/6-311 G(d,p) level. The refractive index (n) was calculated by using the Lorentz-Lorenz equation in order to investigate polarization behavior of complex 1 in different solvent polarities. The first-order static hyperpolarizability ((3) value is found to be lower than pNA value because of the inversion symmetry around Co (II). But the second-order static hyperpolarizability (gamma) value is 2.45 times greater than pNA value (15 x 10(-30) esu). According to these results, Co(II) complex can be considered as a candidate to NLO material. Lastly molecular electrostatic potential (MEP), frontier molecular orbital energies and related molecular parameters for complex 1 were evaluated. (C) 2016 Elsevier Ltd. All rights reserved.Öğe A comparative study of X-ray structural analysis, supramolecular investigation by Hirshfeld surface analysis and DFT computations for tricyclic 1,4-benzodiazepines(Elsevier, 2025) Kurbanova, Malahat; Ahsin, Atazaz; Aliyev, Gaya; Ashfaq, Muhammad; Sahin, Onur; Tahir, Muhammad Nawaz; Abuelizz, Hatem A.The tricyclic 1,4-benzodiazepines - seven-membered heterocyclic compounds were synthesized derived from the three-component reaction involving o-phenylenediamine, 5,5-dimethyl-1,3-cyclohexanedione and various aromatic aldehydes under the influence of HCl. The crystal structure of 11-(3-nitrophenyl)-3,3-dimethyl2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]diazepin-1-one (NDDD) and 11-(2-chlorophenyl)-3,3-dimethyl2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]diazepin-1-one (CDDD) corroborated through single crystal X-ray diffraction method. The Hirshfeld surface analysis indicates crystal packing along with role of intermolecular forces in stabilizing supramolecular assembly of NDDD and CDDD. 2D fingerprint analysis is carried out to envisage to the elemental interactions in the assumption of a single crystal containing molecular fragments. DFT investigations have been carried out to understand the reactivity of NDDD and CDDD at the m062x/def2tzvp method. The obtained geometric parameters from theoretical study are well consistent with experimentally reported XRD analysis. Bonding analysis and charge transfer were examined by performing quantum theory of atoms in molecules (QTAIM) and natural bonding orbital (NBO) analysis. The synthesized NDDD and CDDD exhibit excellent electronic and nonlinear optical properties. The NLO response is justified through computed hyperpolarizability values.Öğe A dual-emitting Rhodamine B-encapsulated Zn-based MOF for the selective sensing of Chromium(VI)(Pergamon-Elsevier Science Ltd, 2024) Shah, Javed Hussain; Sharif, Shahzad; Sahin, Onur; Shahbaz, Muhammad; Azeem, Waqar; Ahmad, SaeedA Rhodamine B-Zn-MOF composite (RhB-Zn-MOF) with dual emission intensity was synthesized through one pot synthesis by in -situ encapsulation of Rhodamine-B dye on a new Zn-MOF metal-organic framework [(Zn (OAc)2(4-BrIPh) (1,10-phenonthroline)(H2O)].H2O, (4-BrIPh = 4-Bromoisophthalic acid). The synthesized encapsulated material was characterized by elemental analysis, FTIR, UV-Visible spectroscopy, TGA, single crystal and powder X-ray diffraction and photoluminescence spectroscopy. The results showed that the synthesized composite, RhB-Zn-MOF could be used as an efficient probe for the selective sensing of Cr(VI) in the presence of Cr(III) as well as other metal ions.Öğe A new decavanadate polyoxovanadate nanocluster: synthesis, characterization and rapid adsorption of methylene blue(Taylor & Francis Ltd, 2017) Naslhajian, Hadi; Amini, Mojtaba; Farnia, S. Morteza F.; Sheykhi, Ayda; Sahin, Onur; Yesilel, Okan ZaferA new decavanadate polyoxovanadate nanocluster, [2-ampH](6)[V10O28].2H(2)O (1), was synthesized through reaction between ammonium vanadate and 2-aminopyridine at pH=2. Nanocluster 1 was characterized by IR, elemental analysis, and X-ray crystallography. 1 was found to adsorb and desorb dyes and may have widespread application in wastewater treatment. The utility of 1 for adsorption of methylene blue was studied. The adsorbed dyes can be easily desorbed, and 1 has full efficiency after five cycles. [GRAPHICS] .Öğe A new Keggin-type polyoxometalate catalyst for degradation of aqueous organic contaminants(Elsevier, 2017) Olgun, Asim; Colak, Alper Tolga; Gubbuk, I. Hilal; Sahin, Onur; Kanar, EbruIn this study, a new polyoxometalate,K-16[Ni(H2O)(6)](2)[BW12O40]4(center dot)48H(2)O (1) was synthesized at room temperature and characterized by X-ray single crystal diffractions, elemental analyses, IR spectra, and thermo gravimetric analyses (TGA). Crystal structure analysis reveals that compound 1 exhibits a supramolecular structure containing one Keggin-type [BW12O40](4) heteropoly anion. The catalytic properties of this molecule for the degradation of Methyl red (MR), Rhodamine B (RhB), Methyl orange (MO) and Congo red (CR) were investigated. The results show that the compound 1 is a promising catalyst candidate for dye degradation. (C) 2016 Elsevier B.V. All rights reserved.Öğe A new zinc(II) complex with N2O2-tetradentate schiff-base derived from pyridoxal-S-methylthiosemicarbazone: Synthesis, characterization, crystal structure, DFT, molecular docking and antioxidant activity studies(Pergamon-Elsevier Science Ltd, 2021) Poladian, Qumars; Sahin, Onur; Karakurt, Tuncay; Ilhan-Ceylan, Berat; Kurt, YaseminA new unsymmetrical N2O2-tetradentate Schiff-base complex of zinc(II) was synthesized by the template reaction of pyridoxal-S-methylthiosemicarbazone and 2-hydroxy-4-methoxy-benzaldehyde as starting compounds. S-methylthiosemicarbazone (1) and zinc(II) complex [Zn(L)CH3OH] ( 2) were characterized by elemental analysis, FT-IR, UV-visible, H-1, and C-13 NMR spectra. The molecular structure of the complex (2) was determined by single crystal X-ray diffraction technique. The structure consists of a distorted square-pyramidal geometry around the central metal, Zn(II). Quantum chemical calculations were carried out using density functional theory DFT/B3LYP, 6-31G (d), and LanL2DZ basis sets for theoretical characterization of the compounds. The experimental and theoretical data were compared comprehensively. The potential energy distribution (PED) analysis was performed for the assignment of vibration frequencies. In order to support in vitro studies, molecular docking studies have been carried out so that the title compound can be an inhibitor of Epidermal Growth Factor Receptor (1 m17), and the relationship between calculated HOMO energies and docking studies has been examined. In addition, the total antioxidant capacity (as TEAC value) and free radical scavenging activity of the compounds were determined by Cupric Reducing Antioxidant Capacity (CUPRAC) and 1,1-diphenyl-2-picryl hydrazyl (DPPH) methods, respectively. (C) 2021 Elsevier Ltd. All rights reserved.Öğe A novel tetrazole-1,8-naphthyridine-amide hybrid: First structurally characterized tetrazolo[1,5-a]-derivative of naphthyridines with a luminescence activity, potency against COVID-19, and anticancer activity(Elsevier, 2025) Adhikari, Suman; Nath, Sourav; Sen, Tanushree; Raza, Rameez; Sahin, Onur; Eftekhari-Sis, Bagher; Mahmoudi, GhodratThis contribution is devoted to a novel tetrazole-1,8-naphthyridine-amide hybrid N-(tetrazolo[1,5-a][1,8] naphthyridin-8-yl)butyramide (1), which was produced from N-(7-chloro-1,8-naphthyridin-2-yl)butyramide by reacting with NaN3. In the crystalline state, molecules of 1 exhibited C-H center dot center dot center dot O intramolecular bonds and produced a 1D chain through N-H center dot center dot center dot N and C-H center dot center dot center dot N contacts. Chains produce a supramolecular 2D layer due to pi center dot center dot center dot pi interactions. In the UV-vis spectrum, 1 exhibits bands up to similar to 360 nm and is emissive with a broad band from about 335 to 450 nm, with the maximum at 365 nm. Fine features of 1 were revealed using the density functional theory (DFT) calculations in water. The computed geometrical parameters are in accordance with the experimental values. The frontier electronic orbitals were found on the molecule except for the propyl fragment, and 1 was determined as a strong electrophile. The computed absorption, distribution, metabolism, elimination and toxicity (ADMET) features predicted positive gastrointestinal absorption (GA) activity and negative human blood-brain barrier (BBB) property of 1. Compound 1 in silico tested to inhibit some of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins. Papain-like protease (PLpro) and Nonstructural protein 3 (Nsp3_range 207-379-MES) were established to interact with 1 more efficiently. The PLpro complex with 1 exhibits a ligand efficiency scores for a Hit. The present study also delved into elucidating the cytotoxic potential of compound 1 in Dalton's Lymphoma (DL) malignant cancer cell lines, aiming to explore its anticancer efficacy. Furthermore, this investigation extends its purview to scrutinize the cytotoxicity profile of the aforementioned compound on normal peripheral blood mononuclear cells (PBMCs), thus enabling a comprehensive comparative analysis of cellular responses under both neoplastic and non-neoplastic cell lines.Öğe A polymeric copper complex based on a pyrazole derivative: Synthesis, spectroscopic, X-ray, and biological activity studies(Wiley, 2024) Amin, Mina A.; Diker, Halide; Sahin, Onur; Varlikli, Canan; Soliman, Ahmed A.A novel 1D coordination polymeric copper complex based on 4-(4 '-nitrophenylhydrazono)-5-trifluoromethyl-2,4-dihydropyrazol-3-one was prepared and characterized spectroscopically and thermally and via X-ray crystallographic investigation. The prepared copper-based structure was proved to have a 1D coordination polymer. X-ray studies showed that the polymeric copper complex was of octahedral geometry, the ligand acted as a bidentate ligand, and the nitro group attached to the ligand acted as a bridging group. The cytotoxic activities of the copper polymer were evaluated including against MCF-7 cells (breast cancer cell line), HepG-2 cells (hepatocellular carcinoma), and HCT-116 cells (colon cancer cell line). The morphological alterations of the complex treated cells were investigated using an inverted microscope. The cell cycle and apoptosis were evaluated and reported. The copper polymer exhibited the best antitumor activity against HepG-2 cells (35.22 +/- 4.80 mu M) while also causing a decline in the G2/M phase and a remarkable enhancement in the early apoptosis. A novel polymeric Cu (II) complex based on 4-(4 '-nitrophenylhydrazono)-5-trifluoromethyl-2,4-dihydropyrazol-3-one was prepared and characterized by spectroscopic, thermal, and X-ray crystallographic analysis techniques. The structure of the prepared complex was proved to have a polymeric nature with a copper center of octahedral geometry. The cytotoxic activities of the polymeric Cu (II) complex were evaluated including against mammalian cell lines: MCF-7 cells (human breast cancer cell line), HepG-2 cells (human hepatocellular carcinoma), and HCT-116 cells (human colon cancer cell line). imageÖğe A square planar cobalt(II)-thiosemicarbazone complex. Synthesis, characterization, antiviral and anti-inflammatory potential(Elsevier, 2025) Atasever-Arslan, Belkis; Kaya, Busra; Sahin, Onur; Ulkuseven, BahriConsidering the possible antiviral effect of cobalt compounds and known pharmacological potential of thiosemicarbazones, a new combination containing cobalt(II) ions and tetradentate thiosemicarbazone was synthesized and structurally analyzed. In the complex structure (Co1), the cobalt ion is in 2+ + oxidation state and is coordinated with ONNO donor set on the thiosemicarbazone backbone. The complex molecule crystallizes in the space group P21/m and the environment of the cobalt center tends to square planar geometry. The inhibitory performance of SARS-CoV-2 and the anti-inflammatory impact of the complex molecule were investigated. It was found that Co1 has high inhibitory effects on the SARS-CoV-2 virus's 3CL main protease enzyme, ACE2:SARSCoV2 Spike RBD interaction, and IL8. Also, it showed significant anti-inflammatory effects on the release of IL6, IL8, IL10, and TGF beta 1 beta 1 cytokines and wound healing during in vitro TNF-alpha-induced inflammation. Experimental evidence demonstrates that Co1 diminishes both IL8 gene expression and protein levels. According to in silico and experimental results, it has a drug potential. Assessing the in vivo impacts of Co1 might contribute to understanding its potential as an antiviral and anti-inflammatory agent.Öğe A theoretical insight for solvent effect on myoglobin assay of W(CO)4L2 type novel complexes with DFT/TDDFT(Elsevier Science Bv, 2016) Ustun, Elvan; Demir, Serpil; Coskun, Feyzullah; Kaloglu, Murat; Sahin, Onur; Buyukgungor, Orhan; Ozdemir, IsmailNovel tetracarbonyl complexes of type W(CO)(4)L-2 (L: 4-chlorobenzylimidazoline; 4-methylbenzylimidazoline; 3,5-dimethylbenzylimidazoline; 2,4,6-trimethylbenzylimidazoline; 2,3,5,6-tetramethylbenzylimidazoline) were synthesized. Then newly synthesized novel compounds were characterized by IR, H-1 NMR, C-13 NMR and LC-MS. The characterizations of two of the complexes have also been confirmed with single crystal X-Ray diffraction and OFT optimization results of these complexes have been compared with single crystal results. We have investigated the solvent effect on the structure and metal-to-ligand charge transfer (MLCT) transitions with OFT/TDDFT calculations with ORCA package program with BP86 functional. (C) 2016 Elsevier B.V. All rights reserved.Öğe a-Glucosidase inhibition properties of novel azaphthalocyanines containing vanillin(Natl Inst Science Communication & Policy Research-Niscpr, 2023) Kantar, Guenay Kaya; Balta, Nimet; Sahin, Onur; Sasmaz, SelamiVanillin substituted novel zinc(II) azaphthalocyanines (ZnAzaPcs) have been synthesized and investigated for their & alpha;-glucosidase inhibition properties. The new compounds (1, 2, 1a and 2a) have been characterised using a combination of FT-IR, 1H and 13C NMR, UV-Vis, MS and elemental analysis. The crystal structures of starting pyrazine compounds 1 and 2 have also been determined by the single crystal diffraction technique. All newly synthesized compounds have been evaluated for their in vitro inhibitory activity against a-glucosidase and all of them have more inhibitory effect when compared to acarbose as reference compound. Especially, compound 2 shows the most significant a-glucosidase inhibition. IC50 values of compound 2 and acarbose, which is known as & alpha;-glucosidase inhibitor used as anti-diabetic drug, have been found to be 6.01 & PLUSMN;0.16 and 9.52 & PLUSMN;0.23 & mu;g/mL, respectively.Öğe Antitumor effects of novel nickel-hydrazone complexes in lung cancer cells(Royal Soc Chemistry, 2020) Ay, Burak; Sahin, Onur; Demir, Burcu Saygideger; Saygideger, Yasemin; Lopez-de-Luzuriaga, Jose M.; Mahmoudi, Ghodrat; Safin, Damir A.In this work we have synthesized and characterized two new mononuclear nickel(ii) complexes [NiLI]center dot CH3CN (1 center dot CH3CN) and [Ni(H2LII)(NCS)(2)]center dot 0.5H(2)O (2 center dot 0.5H(2)O), fabricated from a mixture of Ni(NO3)(2) and KNCS with N ',N '''-(1,2-diphenylethane-1,2-diylidene)di(picolinohydrazide) (H2LI) and 1,2-diphenyl-1,2-bis(((pyridin-2-yl)methylene)hydrazono)ethane (Lig), of which the latter one was transformed in situ into methyl-N-(3,4-diphenyl-5-(pyridin-2-yl)-4,5-dihydro-1H-pyrazol-4-yl)picolinohydrazonate (H2LII) upon coordination to the metal center under synthetic conditions in methanol. The nickel(ii) atom in the structure of complex 1 is tetracoordinated and in a N3O geometry, formed by one doubly deprotonated ligand L-I, linked through the pyridyl nitrogen atom, one of the amide nitrogen atoms, one of the imine nitrogen atoms and one of the carbonyl oxygen atoms, yielding an almost perfect square-planar coordination environment. The crystal packing of 1 center dot CH3CN is dictated by a set of weak non-covalent interactions, namely C-HMIDLINE HORIZONTAL ELLIPSISO, C-HMIDLINE HORIZONTAL ELLIPSIS pi and pi MIDLINE HORIZONTAL ELLIPSIS pi stacking interactions. The asymmetric unit of complex 2 center dot 0.5H(2)O contains two crystallographically independent complex molecules [Ni(H2LII)(NCS)(2)], namely 2-I and 2-II, which are geometrically very similar. The metal atoms are six-coordinated and in a N-6 geometry, formed by one neutral ligand H2LII, linked through two pyridyl nitrogen atoms, one amine nitrogen atom from the pyrazole ring, one imidate nitrogen and two NCS- nitrogen atoms, yielding a distorted octahedral coordination environment. The crystal packing of 2 center dot CH3CN is mainly dictated by intermolecular N-HMIDLINE HORIZONTAL ELLIPSISN, N-HMIDLINE HORIZONTAL ELLIPSISS and O-HMIDLINE HORIZONTAL ELLIPSISS hydrogen bonds, yielding a 3D framework, which is further stabilized by intermolecular pi MIDLINE HORIZONTAL ELLIPSIS pi stacking interactions. From the topological point of view, the hydrogen bonded 3D framework of 2 center dot 0.5H(2)O reveals a four-connected uninodal crb/BCT; 4/4/t5; sqc184 topology. In in vitro experiments, both complexes showed dose dependent cytotoxicity and killed A549 lung cancer cells via an apoptotic pathway. Both complexes also reduced the expression of Snail2, leading to an increase in E-cadherin expression and inhibiting the motility of the cells. The complexes were determined as potential antitumor agents.Öğe Aza-Nazarov Cyclization Reactions via Anion Exchange Catalysis(Amer Chemical Soc, 2019) Donmez, Selin E.; Soydas, Emine; Aydin, Gokcen; Sahin, Onur; Bozkaya, Ugur; Turkmen, Yunus E.A catalytic aza-Nazarov cyclization between 3,4-dihydroisoquinolines and alpha,beta-unsaturated acyl chlorides has been developed to access alpha-methylene-gamma-lactam products in good yields (up to 79%) as single diastereomers. The reactions proceed efficiently when AgOTf is used as an anion exchange catalyst with a 20 mol % loading at 80 degrees C. Computational studies were performed to investigate the reaction mechanism, and the findings support the role of the -TMS group in reducing the reaction barrier of the key cyclization step.Öğe Boric acid complexes with thiamine (vitamin B1) and pyridoxine (vitamin B6)(Elsevier Science Sa, 2014) Kose, Dursun Ali; Zumreoglu-Karan, Birgul; Sahin, Onur; Buyukgungor, OrhanComplexation of boric acid with vitamins B1 (thiamine) and B6 (pyridoxine) was investigated. The products were isolated from aqueous solutions and characterized by elemental analysis, FT-IR, C-13 MAS NMR and thermal methods. The results of chemical and spectral analyses suggested that the reaction between thiaminechloride hydrochloride and H3BO3 in water yielded a salt-like productwith no direct bonding of the thiamine cation to boron while mono- and bis-chelate complexes were obtained with pyridoxine. The bis-chelate pyridoxine complex containing two equivalent pyridoxine ligands was obtained in crystal form. X-ray crystallography verified that complexation with boric acid occurs through the deprotonated phenolic and deprotonated adjacent alcoholic oxygen atoms forming six membered chelate rings. The negative charge on tetrahedral boron is balanced by the sodium ion. The crystal structure contains discernible tunnels parallel to the [010] direction constructed by hydrogen bonded complex molecules. (c) 2014 Elsevier B.V. All rights reserved.Öğe C-C coupling formation using nitron complexes(Royal Soc Chemistry, 2020) Sevim, Mehmet; Kavukcu, Serdar Batikan; Kinal, Armagan; Sahin, Onur; Turkmen, HayatiA series of Ru-II (1), Rh-III (2), Ir-III (3, 4), Ir-I (5) and Pd-II (6-9) complexes of the 'instant carbene' nitron were prepared and characterized by H-1- and C-13-NMR, FT-IR and elemental analysis. The molecular structures of complexes 1-4 and 6 were determined by X-ray diffraction studies. The catalytic activity of the complexes (1-9) was evaluated in alpha(alpha)-alkylation reactions of ketones with alcohol via the borrowing hydrogen strategy under mild conditions. These complexes were able to perform this catalytic transformation in a short time with low catalyst and base amounts under an air atmosphere. Also, the Pd-II-nitron complexes (6-9) were applied in the Suzuki-Miyaura C-C coupling reaction and these complexes successfully initiated this reaction in a short time (30 minutes) using the H2O/2-propanol (1.5 : 0.5) solvent system. The DFT calculations revealed that the Pd-0/II/0 pathway was more preferable for the mechanism.Öğe Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles(Beilstein-Institut, 2023) Yagci, Bilge Banu; Donmez, Selin Ezgi; Sahin, Onur; Turkmen, Yunus EmreWe have developed a catalytic aza-Nazarov reaction of N-acyliminium salts generated in situ from the reaction of a variety of cyclic and acyclic imines with alpha,13-unsaturated acyl chlorides to afford substituted alpha-methylene-gamma-lactam heterocycles. The reactions proceed effectively in the presence of catalytic (20 mol %) amounts of AgOTf as an anion exchange agent or hydrogen-bond donors such as squaramides and thioureas as anion-binding organocatalysts. The aza-Nazarov cyclization of 3,4-dihydroisoquinolines with alpha,13-unsaturated acyl chlorides gives tricyclic lactam products 7 in up to 79% yield with full diastereocontrol (dr = >99:1). The use of acyclic imines in a similar catalytic aza-Nazarov reaction with 20 mol % of AgOTf results in the formation of alpha-methylene-gamma-lactam heterocycles 19 in up to 76% yield and with good to high diastereoselectivities (4.3:1 to 16:1). We have demonstrated the scalability of the reaction with a gram-scale example. The relative stereochemistry of the alpha-methylene-gamma-lactam products 19 has been determined via the single-crystal X-ray analysis of lactam 19l. In order to shed light on the details of the reaction mechanism, we have performed carefully designed mechanistic studies which consist of experiments on the effect of 13-silicon stabilization, the alkene geometry of the alpha,13-unsaturated acyl chloride reactants, and adventitious water on the success of the catalytic aza-Nazarov reaction.Öğe Chelate ring stacking interactions in the supramolecular assemblies of Zn(II) and Cd(II) coordination compounds: a combined experimental and theoretical study(Royal Soc Chemistry, 2017) Afkhami, Farhad Akbari; Khandar, Ali Akbar; Mahmoudi, Ghodrat; Maniukiewicz, Waldemar; Gurbanov, Atash V.; Zubkov, Fedor I.; Sahin, OnurThe self-assembly of Zn(II) and Cd(II) ions with two isomeric tetradentate ligands, 2-pyridyl-isonicotinoylhydrazone (HL1) and 2-benzoylpyridyl-picolinoylhydrazone (HL2), was studied by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The reaction of zinc(II) and cadmium(II) salts with HL1 and HL2 in methanol under solvothermal conditions produced six monomer and one tetranuclear zinc(II) complexes, namely, Zn(HL1) Br-2 (1), Zn(HL1)Cl-2 (2), [Cd(HL1)(2)](NO3)(2)center dot H2O (3), Cd(HL2)Br-2(4),Zn(HL2)Cl-2 (5), Zn(HL2)Br-2 (6) and [Zn-4(L-2)(4)I-2][ZnI4]center dot 2H(2)O (7). The structure of 7 includes a cationic tetranuclear cluster of four zinc ions, four ligands, and two anions, counterbalanced by ZnI42- ions. However, the reaction of zinc(II) and cadmium(II) salts with HL1 under the same conditions produced monomer compounds. Herein, the ligand effects on the complex structures were studied. Hirshfeld surface analysis and fingerprint plots facilitate the comparison of intermolecular interactions in compounds 1-7, which are crucial in building supramolecular architectures.Öğe Cobalt(II)/(III) complexes bearing a tetradentate thiosemicarbazone: Synthesis, experimental and theoretical characterization, and electrochemical and antioxidant properties(Wiley, 2020) Kaya, Busra; Akyuz, Duygu; Karakurt, Tuncay; Sahin, Onur; Koca, Atif; Ulkuseven, BahriNew cobalt complexes,Co1andCo2, were synthesized starting from acetylacetone-S-methylthiosemicarbazone. The square planar cobalt(II) and octahedral cobalt(III) complexes were characterized by FT-IR, UV-visible,H-1 NMR, and X-ray diffraction spectroscopies and mass spectrometry. Frontier orbitals of the complexes were theoretically obtained to better understand the complex structures and intermolecular interactions. The electrochemical behaviors ofCo1andCo2were investigated and the results were evaluated by comparing with each other and with similar published compounds to determine their possible usage in various electrochemical technologies, such as energy storage devices, electrocatalysts, and electrosensors. Metal-based oxidation at around 0 V and metal-based reduction at around -1.0 V indicated that these complexes are valuable for the proposed applications. By determining the trolox equivalent antioxidant capacity and the radical scavenging activity of the cobalt complexes, the compatibility between the antioxidant qualification, redox, and theoretical calculation results was discussed.
