Browsing by Author "Menges, Nurettin"

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Cettaertalyst-Free Hydrogenation of Alkenes and Alkynes With Hydrazine in the Presence of Oxygen
(Georg Thieme verlag Kg, 2014) Menges, Nurettin; Balci, Metin
A series of alkenes and alkynes was subjected to reduction with hydrazine hydrate in ethanol in the presence of oxygen. An efficient method was developed for the reduction of C-C double bonds and C-C triple bonds with diimide, generated in situ from hydrazine hydrate by oxidation with oxygen. The reduction process proceeded for 24-48 hours with high chemoselectivity and excellent yields. This reduction procedure offers synthetic advantages over metal-catalyzed hydrogenation as well as other systems.
Computational Study on Aromaticity and Resonance Structures of Substituted Bodipy Derivatives
(Elsevier, 2015) Menges, Nurettin
We have developed a systematic study for the investigation of resonance structures of the substituted BODIPYs. Aromaticity of two rings of BODIPY were calculated by means of NICS (Nucleus independent chemical shift) values and these values gave us an insight to predict dominant resonance structure between two different resonance forms of BODIPYs. Furthermore, bond order comparisons were utilized to specify dominant forms of the resonance structures. BODIPYs substituted with electron donating (EDG) or withdrawing groups (EWG) at different positions were analyzed and it was observed that character of substituents affected the aromaticity as well as dominant resonance structure. Substituent positions were also investigated and some important points were yielded from these calculations. We further extended the study to aromaticity of pyridine or benzene[b]-fused BODIPYs. (C) 2015 Elsevier B.V. All rights reserved.
Copper-Catalyzed Synthesis of Fused Imidazopyrazine N-Oxide Skeletons
(Georg Thieme verlag Kg, 2019) Tasdemir, Volkan; Kuzu, Burak; Tan, Meltem; Genc, Hasan; Menges, Nurettin
N-Propargyl-2-aroylimidazoles synthesized and converted into the corresponding ketoximes. Under various conditions, several mono- and diketoxime imidazole derivatives were formed by converting the carbonyl or carbonyl and propargyl groups into oxime groups. N-Propargyl monooxime imidazole derivatives were cyclized by treatment with CuI to give various imidazopyrazine N-oxides. Several copper salts, such as CuOAc, CuSO (4) , and CuOTf, formed the same cyclization product. This cyclization reaction occurred only in the presence of Cu(I) or Cu(II) salts; other transition metals such as Au, Ag, In, and Fe did not yield cyclic products. The nucleus-independent chemical shift method was used to calculate the aromaticity of the bicyclic rings.
Design and Synthesis of Esipt-Based Imidazole Derivatives for Cell Imaging
(Amer Chemical Soc, 2024) Gul, Sergen; Acikgoz, Eda; Cakir, Mustafa; Menges, Nurettin
Excited-state intramolecular proton transfer (ESIPT)-based fluorescent molecules offer several exciting applications and are utilized most frequently as a cell imaging agent. Because of this, four distinct imidazole derivatives with ESIPT emission have been synthesized, and their fluorescence characteristics have been assessed in a variety of settings. Measurements using fluorescence spectroscopy have shown a promising candidate for cell staining, and potential candidate was specifically investigated for cell imaging uses in HT-29, MDA-MB-231, and HaCaT. Cytotoxicity of candidate molecule (1d) was analyzed using HT-29 and HaCaT cell lines, and at a dosage of 160 mu M, HT-29 and HaCaT cell lines showed no signs of important cell toxicity. When spectroscopically measured, compound 1d showed no fluorescence ability in phosphate-buffered saline (PBS) solution. However, after 8 h of incubation in several cell lines, excellent fluorescence characteristics were seen in the green and red filters.
Design and Synthesis of Pyrrolotriazepine Derivatives: an Experimental and Computational Study
(Amer Chemical Soc, 2013) Menges, Nurettin; Sari, Ozlem; Abdullayev, Yusif; Erdem, Safiye Sag; Balci, Metin
The pyrrole derivatives having carbonyl groups at the C-2 position were converted to N-propargyl pyrroles. The reaction of those compounds with hydrazine monohydrate resulted in the formation of 5H-pyrrolo[2,1-d][1,2,5]-triazepine derivatives. The synthesis of these compounds was accomplished in three steps starting from pyrrole. On the other hand, attempted cyclization of a pyrrole ester substituted with a propargyl group at the nitrogen atom gave, unexpectedly, the six-membered cyclization product, 2-amino-3-methylpyrrolo[1,2-a]pyrazin-1(2H)-one as the major product. The expected cyclization product with a seven-membered ring, 4-methyl-2,3-dihydro-1H-pyrrolo[2,1-d][1,2,5]-triazepin-1-one was formed as the minor product and was converted quantitatively to the major product. The formation mechanism of the products was investigated, and the results obtained were also supported by theoretical calculations.
Design, Synthesis and Antimicrobial Activities of New Carbon Nanotubes Derivatives
(2021) Alma, M.hakki; Yiğit, Aybek; Akinay, Yuksel; Menges, Nurettin
Even though natural products or crops have been more common and popular in the recent, the chemicals without side-effects have been also addressed in various fields of industries due to possibility obtaining the large quantity and more bio-efficacy. In that context, many drugs have been developed for antibacterial activities but the over-uses of those relevant drugs have caused that microorganisms have adapted and evolved resistance against those drugs. Those lead to the researchers to focus on newly synthesized or functionalized molecules. In that context, nanotechnology, especially modified nanocarbon tubes (NCTs), are of the great interest of the various industries. Along with the current study, multi-walled carbon nanotubes (MWCNTs) were functionalized with three steps. Firstly, the carbon nanotube with a carboxylic acid tip on its surface was commercially purchased and then converted into acyl chloride, and later converted into a more reactive group. Then, the nucleophilic amino group such as diethylene triamine is bonded onto the carbon nanotube. Finally, after the carbon nanotube material with amine groups was functionalized with boric acid, carbon nanotube molecules carrying boric acid molecules were synthesized. Following modification and functionalization of MWCNTs, the newly synthesized molecules were characterized using FT-IR, SEM, TEM and XPS. After chemical characterization, the relevant molecules were screened for their anti-bacterial activities in comparison to those of well-known antibiotics. For anti-bacterial assays, molecules were tested against K. pneumoniae, E. coli, P.aeruginosa, S. aureus and B. subtilis. Concerning the findings of the antibacterial assays, concentrations of 40 and 80 μg /mL exhibited a range of activities but in parallel with those of standard antibiotics whereas the lower concentration, viz. 5, 10 and 20 μg / mL did not exhibit any activities. The highest activity was noted for 80 μg / mL, in comparison to those of antibiotics and other concentrations, against B. subtilis, with a 23 mm inhibition zone.
Determination of the Enol Form of Asymmetric 1,3-Dicarbonyl Compounds: 2d Hmbc Nmr Data and Dft Calculations
(Serbian Chemical Soc, 2018) Tan, Meltem; Bildirici, Ishak; Menges, Nurettin
In this study, a series of asymmetric aryl 1,3-dicarbonyl compounds were synthesized and their enol forms were observed via experimental data and theoretical calculations. According to the H-1- and C-13-NMR results, all the investigated compounds were found as a single enol form in CDCl3 solution. Moreover, their HMBC spectra were applied to identify the observed enol forms and correlations between certain protons and carbon atoms were considered. The dihedral angles of the asymmetric compounds that have aryl units on both sides were calculated by DFT to understand the reason for the observed enol forms. Small dihedral angles caused longer conjugation, resulting in more stable compounds and it was found that the observed enol forms were based on small dihedral angles, namely, resonance is the driving force. Furthermore, the compounds possessing both aryl and alkyl moieties prefer the enol form towards the aromatic ring side due to longer conjugation.
An Easy Synthetic Protocol for Imidazo-1,4 and Evaluation of Their Toxicities
(Wiley-hindawi, 2018) Kuzu, Burak; Genc, Hasan; Taspinar, Mehmet; Tan, Meltem; Menges, Nurettin
Imidazo-1,5-alkynyl alcohol derivatives were synthesized, and they were cyclized to imidazo-1,4-oxazines by means of cesium carbonate. Propargyl-allene isomerization was examined, and the reaction mechanism was proposed. Moreover, cytotoxicity of synthesized molecules against LN405 cell lines was investigated by means of structure-activity relationship (SAR). With SAR study, toxicities of some functional groups have been shown. In addition, two lead compounds were tested against DNA damaging.
Effect of Direct Linkage of Pyrazole Carboxylic Acid Acceptor/Anchoring Group on the Photovoltaic Performance for Phthalocyanine-Sensitized Solar Cells
(Elsevier Sci Ltd, 2022) Yildiz, Burak; Ahmetali, Erem; Arslan, Baris Seckin; Menges, Nurettin; Nebioglu, Mehmet; Sisman, Ilkay; Sener, M. Kasim
An unsymmetrical zinc phthalocyanine dye (PCA-ZnPc-4) containing six electron donating hexylsulfanyl groups and a pyrazole-3-carboxylic acid anchoring group which is directly linked to the macrocycle was synthesized to evaluate the photophysical, electrochemical, and theoretical characteristics as well as photovoltaic properties. Previously studied dye PCA-ZnPc-2 , which contains the same electron donating groups and pyrazole-3-carboxylic acid anchoring group with the bridging oxygen atom, was used as a reference dye. The optimized dye-sensitized solar cell (DSSC) based on PCA-ZnPc-4 exhibited an impressive power conversion efficiency of 2.52% (J(SC) = 6.53 mA cm(-2) , V-OC = 0.584 V, FF = 0.66), exceeding that of the DSSC based on PCA-ZnPc-2 (1.86%) under the same conditions. The better photovoltaic performance of PCA-ZnPc-4 is mainly due to its conjugated anchoring group, leading to efficient electron injection. This work demonstrates that the anchoring groups attached to the macrocycle without oxygen linker may enhance the photovoltaic performance of the phthalocyanine-sensitized solar cells.
Efficient Synthesis of Some Oxalacetic Acid and Pyruvic Acid Derivatives From the Reactions of 2,3-Furandiones With 2-Phenylindole
(Pergamon-elsevier Science Ltd, 2008) Sener, Ahmet; Menges, Nurettin; Akkurt, Mehmet; Karaca, Selvi; Bueyuekguengoer, Orhan
Oxalacetic acid and pyruvic acid derivatives have been synthesized efficiently in high yields by the treatment of 4-ethoxycarbonyl-5phenyl-2,3-furandione and 4-benzoyl-5-phenyl-2,3-furandione with 2-phenylindole at room temperature and converted to simple derivatives such as an ester or a hydrazone. (C) 2008 Elsevier Ltd. All rights reserved.
An Entry Into Obtaining Pyrazole-, Chromone-, or Oxadiazole-Substituted 1h-Pyrazoles Via 2,3-Furandiones
(Wiley, 2013) Cam, Serkan; Bildirici, Ishak; Menges, Nurettin; Tan, Meltem; Sener, Ahmet
Some new pyrazole-, chromone-, or oxadiazole-substituted 1H-pyrazoles were obtained via 2,3-furandiones. Also, we have presented their plausible mechanisms based on rearrangement; one of these rearrangements is BakerVenkataraman.
Excited State Intramolecular Proton Transfer (esipt)-Based Sensor for Ion Detection
(Springer/plenum Publishers, 2021) Kuzu, Burak; Ekmekci, Zeynep; Tan, Meltem; Menges, Nurettin
C-2 and C-5 substituted imidazole skeleton was synthesized through a one-pot two-step strategy. Synthesized molecule emits the light on ESIPT (excited-state intramolecular proton transfer). This molecule was utilized for its proton donor ability, and we have observed that fluoride and cyanide ions can be detected selectively. Different cations and anions were selected to observe the response of the synthesized molecule. However, there were not any fluorometric and colorimetric response except for fluoride and cyanide ions. Detection limits of fluoride and cyanide ions were found to be 9.22 mu M and 11.48 mu M, respectively. H-1-NMR spectra for the solution of the sensor and TBAF (tetrabuthylammoniumfluoride) were used for the identification of [L](-)[HF2](-) species. 3 equiv. TBAF saturated the solution of the sensor in d(6)-DMSO, and some of the proton resonances shifted to upfield due to the through-bond effect. The disappearance of NH proton with 0.5 equiv. TBAF or TBACN (tetrabuthylammoniumcyanide) showed that there was a proton abstraction by fluoride and cyanide ions, instead of the hydrogen bond. Solid-state application was utilized, and paper test strips were applied. Emission differences emerged when the sensor loaded strips were reacted with TBAF. Time resolved experiments revealed that solution of the sensor and TBAF in DMSO have multiexponential decay, and one of the lifetime was measured as 13.4 ns.
Exploring of Indole Derivatives for Esipt Emission: a New Esipt-Based Fluorescence Skeleton and Td-Dft Calculations
(Elsevier Science Sa, 2021) Kaya, Serdal; Aydin, Hatice Gulten; Keskin, Selbi; Ekmekci, Zeynep; Menges, Nurettin
ABS T R A C T Appropriate synthesis methods gave six different indole derivatives substituted at the C-2 or C-3 position. ESIPT emission capacities of these derivatives were investigated. It was concluded that the indole derivative containing the 1,2-dicarbonyl group at the C-2 position has ESIPT emission. Although adding water to the DMSO solution of the ESIPT-based molecule (9:1) resulted in ESIPT quenching, steady-state measurements in MeOH did not occur ESIPT quenching. TD-DFT calculation for uncovering the ESIPT mechanism emerged that the ESIPT mechanism occurred as a barrierless process. The X-ray analysis and DFT conformational analysis revealed that NH and CO groups involving proton transfer mechanisms are in the cis position. A mono-exponential decay was observed in DMSO and MeOH solutions, in which lifetimes were measured as 6.1 and 5.5 ns, respectively. pH studies revealed that acidic and basic solutions of molecule 7 did not influence ESIPT emission.
Floroiyonofor Özelliğine Sahip Akıllı Moleküllerin Sentezi ve Katyon Analizindeki Uygulamaları
(2017) Tan, Meltem; Menges, Nurettin
Bu çalışmada katyon ve anyon analizini floresans ışıma üzerinden mümkün hale getirecek imidazol halkasına sahip bileşikler sentezlendi. Moleküller iki kademede ve tek reaksiyon kabında basit saflaştırma teknikleri ile elde edildi. Elde edilen imidazol bileşikleri farklı katyon belirleme deneylerinde kullanıldı. Sentezlenen moleküller arasında en iyi floresans ışımayı belirlemek için moleküllerin farklı çözücülerdeki floresans ışıma spektrumları alındı. İmidazol bileşiğinin karbonil grubunun oksime çevrilmesi ile elde edilen molekülün ferrik iyonlarına karşı seçimli ve hassas bir belirleme yeteneğine sahip olduğu belirlendi. Sentezlenen floresans ışımaya sahip molekülün ferrik iyonlarına karşı ışıma tepkisi ESIPT (uyarılmış hal molekül içi proton transferi) mekanizması üzerinden gerçekleştiği teorik ve deneysel olarak belirlendi. Elde edilen moleküller arasından, tiyofen halkasına sahip imidazol molekülünün flor iyonlarına karşı birçok iyon arasından seçici olarak tepki verdiği belirlendi. Bu tepkinin, floresans ışıma, görünür bölge renk değişimi olarak tespit edilebildiği ortaya çıkartıldı. Işıma değişimlerinin, bazı fonksiyonel grupların ve düzlemselliğin floresans ışıma üzerine ne tür etkileri olduğu teorik olarak tartışıldı. Bu tartışmanın bilimsel altyapısının hazırlanması için birçok moleküller modelleme yapıldı. Yürütülen çalışmada yeni bir floresans ışımaya sahip imidazol iskeletine sahip molekül serisi belirlendi ve bu molekül serisinin hangi mekanizma üzerinden ışımasını değiştirdiği deneysel ve teorik olarak ortaya çıkartıldı.
Gold-Catalyzed Cyclization of Non-Conjugated Ynone-Oxime Derivatives: Incorporation of Solvent Molecule
(Wiley-v C H verlag Gmbh, 2020) Tasdemir, Volkan; Menges, Nurettin
Au-iii-promoted cyclization reaction of ynone-oxime derivatives furnished 4H-1,2-oxazine ring under mild reaction conditions. When an alcohol is present in the reaction media, it was attached to the oxazine ring by the second activation of cyclic intermediate with a gold catalyst. Cholesterol, propargyl alcohol, phenol, and some of the different alcohol derivatives with alkyl chain were bonded to the oxazine ring in good yields. While amine derivatives did not attach to the ring under optimized reaction conditions, the molecule with the thiol group deactivated the gold catalyst under the same reaction conditions and did not give any cyclic products. With the obtained cyclization protocol, 11 unknown oxazine derivatives were synthesized and characterized. The proposed cyclization mechanism was drawn according to the two independent control experiments, DFT optimization, and NBO charges.
Gold-Catalyzed Cyclization of Unconjugated Ynone Derivatives for 2h-1,2 and 1-Hydroxypyrrole Skeletons Through One-Pot and Single-Step Strategy
(Springer int Publ Ag, 2023) Tasdemir, Volkan; Menges, Nurettin
Unconjugated ynone derivatives with the 1,3-dicarbonyl structure are synthesized, and they are directly subjected to goldcatalyzed reaction with hydroxylamine without obtaining the oxime derivative. Among the different metal salts investigated, AuCl3 is the best for yielding and obtaining two different heterocyclic skeletons. Thanks to this reaction, two important heterocyclic molecules, 2H-1,2-oxazine and 1-hydroxypyrrole, are obtained as a one-pot and single-step strategy with favorable yields. Eleven different 2H-1,2-oxazine and 6 different 1-hydroxypyrrole derivatives are synthesized using starting compounds containing different substituents, in which steric hindrance and electronic effect are also taken into account. When the same reaction is carried out with the unconjugated ynone derivative containing only one carbonyl group, the only 1-hydroxypyrrole derivative is observed to be formed, and 1,2- oxazine ring is not observed.
Gold-Catalyzed Formation of Pyrrolo- and Indolo-Oxazin Derivatives: the Key Structure of Some Marine Natural Products
(Beilstein-institut, 2015) Taskaya, Sultan; Menges, Nurettin; Balci, Metin
Various N-propargylpyrrole and indolecarboxylic acids were efficiently converted into 3,4-dihydropyrrolo- and indolo-oxazin-1-one derivatives by a gold(III)-catalyzed cyclization reaction. Some of the products underwent TFA-catalyzed double bond isomerization and some did not. Cyclization reactions in the presence of alcohol catalyzed by Au(I) resulted in the formation of hemiacetals after cascade reactions.
Gold-Catalyzed Oxime-Oxime Rearrangement
(Amer Chemical Soc, 2015) Guven, Sinem; Ozer, Merve Sinem; Kaya, Serdal; Menges, Nurettin; Balci, Metin
The gold-catalyzed reaction of pyrrole and indole oximes having a propargyl group attached to the nitrogen atom was studied. The selective 6-endo-dig mode of cyclization was observed for the terminal alkynes giving rise to the formation of pyrazine N-oxides in the presence of a gold catalyst. However, the reaction with substituted alkyne transferred the oxime functionality intramolecularly from one carbon atom to another via the 7-endo-dig cyclization process. This transformation is unprecedented in the literature and is named an oximeoxime rearrangement.
A Golden Synthetic Approach To 2-(1 H -Pyrrol and Pyrrolo[1,2-A ]quinoxalines Through a Gold Carbene Intermediate
(Georg Thieme verlag Kg, 2024) Tasdemir, Volkan; Genc, Hasan; Menges, Nurettin
The pyrrolo[1,2-a]quinoxaline skeleton has significant potential for many biological and optical applications. Hence, in this study, unconjugated ynone derivatives were treated with 1,2-diaminoarenes in a gold-catalyzed cyclization to give 2-(1H-pyrrol-1-yl)anilines, which are valuable starting materials, and pyrrolo[1,2-a]quinoxalines by a one-pot and single-step approach. A reaction mechanism for the formation of the pyrrolo[1,2-a]quinoxaline skeleton featuring a key gold carbene intermediate is proposed. On the other hand, the methyl group on the C-2 position of the 2-(1H-pyrrol-1-yl)anilines was oxidized by SeO2 to give the pyrrolo[1,2-a]quinoxaline skeleton, resulting in 14 different pyrrolo[1,2-a]quinoxaline derivatives.
Highly Selective Electrochemical Sensor for New Generation Targeted-Anticancer Drug Ibrutinib Using Newly Synthesized Nanomaterial Go-Nh Modified Glassy Carbon Electrode
(Elsevier Sci Ltd, 2023) Amudi, Karina; Yigit, Aybek; Menges, Nurettin; Pinar, Pinar Talay
Ibrutinib (IBR) is a small molecule new generation smart anti-cancer drug that is Bruton's tyrosine kinase (BTK) inhibitor. In this study, the sensitive and selective electrochemical sensor based on a modification of a glassy carbon electrode with a new GO-NH-B(OH)2 (graphene oxide boramidic acid) nanoparticles and Ag nano -particles (AgNPs) is proposed for IBR determination. GO-NH-B(OH)2@AgNPs/GCE was characterized by scan-ning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The performance of the electrode was evaluated with the parameters of electrode surface area (A), heterogeneous rate constant (ket), standard exchange current density (I0). The electrochemical determination of IBR in 0.1 M HNO3 solution was investigated at the surface of GO-NH-B(OH)2@AgNPs/GCE. Under optimized square wave voltammetric (SWV) conditions, peaks current at GO-NH-B(OH)2@AgNPs/GCE showed good linearity with the concentration of IBR in the operating range of 0.025-1.00 mu g mL-1 (5.7 x 10-8 - 2.3 x 10-6 M) with a detection limit (LOD) of 0.006 mu g mL-1 (1.36 x 10-8 M). Besides its high stability and reproducibility, the response of IBR at GO-NH-B (OH)2@AgNPs/GCE was not influenced by the presence of dopamine, uric acid, and ascorbic acid. The sensor has successfully caught IBR in pharmaceutical and human urine samples.