Yazar "Kaya, Yunus" seçeneğine göre listele
Listeleniyor 1 - 9 / 9
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Conformational, spectroscopic, optical, physicochemical and molecular docking study of 4-methoxy-benzaldehyde oxime and 4-hydroxy-3-methoxy-benzaldehyde oxime(Taylor & Francis Ltd, 2020) Kaya, Yunus; Kucuk, Ilhan; Kaya, Asli A.In this study, the conformational, spectroscopic, optical, physicochemical and molecular docking studies of two oxime molecules, namely 4-methoxy-benzaldehyde oxime (mboH) and 4-hydroxy-3-methoxy-benzaldehyde oxime (hmboH) were reported. The conformational analyses and spectroscopic properties were performed by DFT/B3LYP method and 6-311++G(d,p) basis set to find the most probable geometries of both molecules. The optical properties, energy gap and nonlinear optical (NLO) properties were investigated in different solvents which are benzene, chloroform, ethanol, dimethyl sulfoxide (DMSO) and water. Some physicochemical properties were also performed. The stability of the mboH and hmboH arising from hyper-conjugative interaction and charge delocalisation has been analysed using natural bond orbital (NBO) analysis. The stability of the molecules arising from hyper conjugative interactions and charge delocalisation has been also analysed using NBO study. In addition, molecular docking studies with DNA and protein structures to find the most preferred binding mode of the ligands inside the DNA and protein cavity.Öğe High diastereoselectivity induced by intermolecular hydrogen bonding in [3+2] cycloaddition reaction: experimental and computational mechanistic approaches(Wiley, 2017) Yildirim, Ayhan; Kaya, YunusA diastereoselective [3 + 2] cycloaddition of N-aryl substituted maleimides with N, a-diphenyl nitrone possessing 11-hydroxyundecyloxy as a flexible substituent was performed. Experimental and comprehensive mechanistic density functional theory studies reveals that intermolecular H-bonding and steric repulsive interaction predominate exo-Z and exo-E cycloaddition transition states, respectively. The reaction proceeded smoothly depending on the reactants and gave a good yield of (syn) cis-isoxazolidine or (anti) trans-isoxazolidine as a single diastereomer.Öğe Investigation of structural, spectral, optical and nonlinear optical properties of nanocrystal CdS: Electrodeposition and quantum mechanical studies(Elsevier GmbH, 2021) Erturk, Kadir; Isik, Seref; Aras, Ömür; Kaya, YunusNanocrystalline CdS semiconductor was synthesized by electrodeposition technique, and characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and FTIR spectroscopic methods. XRD analysis result showed that it is a hexagonal crystal structure. SEM micrographs showed that the CdS nanocrystal is homogeneously distributed on the surface. The roughness of the CdS thin films was measured by AFM. The presence of band in the FTIR spectrum at 558 cm−1 corresponds to the stretching of CdS. CdS nanocrystals were modeled separately and calculated in the Gaussian program. Structural, spectroscopic, and nonlinear optical (NLO) properties were investigated using the DFT/Lanl2dz and semi-empirical/pm6 level. Besides, by making energy calculations, Homo, Lumo, band gap, and total state density (TDOS) were calculated. The experimental band gap was measured at 2.40 eV, while this calculated for hexagonal and cubic structure as 2.21 and 2.01 eV with semiemprical/pm6 model, 2.44 and 2.25 eV with DFT/lanl2dz level.These results support that CdS nanostructures are crystallized in hexagonal structure. With this study, the obtaining of nano structured CdS films by electrodeposition method, their structural, optical and surface properties were experimentally examined, supported by theoretical calculations, and additionally NLO properties were investigated. It has been determined that the nanocrystals obtained are suitable material for optoelectronic applications.Öğe Qualitative study on the effects of hydroxyl functionalized multiwall carbon nanotube and silica doped-epoxy composites(John Wiley and Sons Inc, 2022) Yaşaroğlu, İnci; Aras, Ömür; Kaya, YunusEpoxy resins have great potential for industrial applications because of their excellent properties such as good adhesion, durability, higher strength, and so forth. But, their high-viscosity limits industrial usage. Reducing the viscosity with suitable diluents provides an advantage on industrial scale processing, but this also causes a decrease in their chemical and mechanical properties. The production of epoxy-based composite materials provides good mechanical, heat, and solvent resistance properties. Therefore, determination of additives amount and dilution ratio for specific working area are important for these materials. In this context, this study first includes synthesis of bisphenol A-based epoxy resin and characterization with fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Second, chemical, mechanical, thermal, and surface properties of the resin were investigated by varying the reactive/nonreactive diluents and additives. Multiwall carbon nanotube (MWCNT-modified with triton X-405 nonionic surfactant) and fumed silica as additives were used in this study. Mechanical and chemical tests were applied to 49 types of materials. In order to see the significance levels and synergistic effects of diluents on tensile strength, 3D graphs were obtained with the experimental and modeled data. ANOVA was also performed for significance levels of the diluents. After that, the effects of silica and carbon nanotube additive on tensile strength were investigated. As a result of the tensile test and TGA analysis of the pure epoxy, the ultimate tensile strength was measured as 59.07 MPa, Tg (°C), and Tm (°C) values were found as 175.5 and 304.0°C. These results increased for the nanocomposite material prepared with 2% fumed silica and 0.1% MWCNT (modified YAM) as 81.64 MPa, 192.2 and 333.3°C. It was also shown that the ultimate tensile strength, which decreased with dilution of pure epoxy, could be increased significantly with the additivesÖğe Quantum Chemical Studies of the Substituent Effect on the Reaction of Carbonyl Oxime with Amine(Amer Chemical Soc, 2016) Kaya, YunusThe reaction of the two different substitue carbonyl oximes (isonitrosoacetylnaphthaline, inanH and nitro-isonitrosoacetophenone, ninapH) with two different amines (1-phenylethanol amine, pea, and ethanol amine, ea) was carried out and characterized by elemental analyses, IR, and H-1 and C-13 NMR spectroscopic methods. As a result of these experimental studies, two different levels for all reactions were determined: (I) formation of imine oxime and (II) rearrangement of imine oxime or formation of amido alcohol. After a mechanism was suggested for all of these reactions, the reaction mechanism of carbonyl oxime with amine was first studied by means of the B3LYP/6-311G(d,p) method. Because of the deficiency of density functional theory (DFT) on dispersion effects, the wB97X-D/6-311G(d,p) method, which includes dispersion correction, was used to obtain the reaction heat and free energy barriers to explain why the formation (imine oxime) and unexpected rearrangement products (amido alcohol) occurred or did not occur. The statistical thermodynamic method was used to obtain the changes in thermodynamic properties of the studied molecules between 100 and 500 K. From a kinetic viewpoint, the slowest step of the reactions is the IN1-TS2-IN2 step, which determines the steps of the reaction kinetics. In addition, spectroscopic properties such as vibrational and NMR chemical shifts were studied for all of the molecules. The frontier molecular orbitals (FMOs), highest occupied molecular orbitals (HOMOs), and lowest unoccupied molecular orbitals (LUMOs) were monitored for all of the molecules.Öğe Screening of simple carbohydrates as a renewable organocatalyst for the efficient construction of 1,3-benzoxazine scaffold(Elsevier Ltd, 2021) Yıldırım A.; Kaya, Yunus; Göker M.A convenient protocol for the two component preparation of 1,3-benzoxazines by using several protected and unprotected carbohydrate molecules as organocatalysts have been developed which is broadly applicable to condensation reaction between variety of Mannich bases and paraformaldehyde. This study revealed that fructose have much higher catalytic activity than the other carbohydrates and can be an alternative to metal-containing catalysts as a green renewable organocatalyst for efficient and rapid construction of 1,3-benzoxazine skeleton. In this context, 21 benzoxazine compounds were successfully synthesized and spectral characterizations of these compounds were carried out by spectroscopic methods and elemental analysis. Furthermore, density functional theory (DFT) calculations have been performed to study the detailed mechanism of organocatalyst assisted synthesis of the benzoxazine monomers. The results obtained from these calculations showed that the more realistic reaction pathway involves formation of a phenolate based intermediate which loses a water molecule to form benzenaminium ion. Subsequently, this ion provides the formation of the corresponding benzoxazines with good yields through the intramolecular ring closure step.Öğe Structural, spectroscopic (FT-IR, NMR, UV-visible), nonlinear optical (NLO), cytotoxic and molecular docking studies of 4-nitro-isonitrosoacetophenone (ninapH) by DFT method(Elsevier, 2017) Küçük, İlhan; Kaya, Yunus; Kaya, A. Asli(4-Nitro-phenyl)-oxo-acetaldehyde oxime (ninapH) is a type of oxime, which has a oxime and alpha-carbonyl groups. This molecule has been synthesized from literature procedure. The structural properties and conformational behaviors were examined using the density functional theory (DFT) with the B3LYP method combined with the 6-311++G(d,p) basis set. As a result of the conformational studies, the most stable conformer was determined, and then this molecule was optimized with the same basis set. Comprehensive theoretical and experimental structural studies on the molecule have been carried out by FT-IR, NMR and UV-vis spectrometry. The calculated HOMO and LUMO energies show that charge transfer within the molecule. The first order hyperpolarizability and molecular electrostatic potential (MEP) were also performed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the ninapH have been calculated at different temperatures, 100-1000 K. In addition, the molecular docking studies have been, performed with DNA and protein structures (downloaded from Protein Data Bank). (C) 2017 Elsevier B.V. All rights reserved.Öğe Structural, vibrational, NMR, quantum chemical, DNA binding and protein docking studies of two flexible imine oximes(Indian Acad Sciences, 2016) Kaya, YunusTwo flexible imine oxime molecules, namely, 3-(pyridin-2-ylmethylimino)-butan-2-one oxime (HL (1)) and 3-(pyridin-2-ylmethylimino)-pentan-2-one oxime (HL (2)) have been synthesized and characterized by elemental analysis, IR and NMR techniques. The conformational behavior was investigated using the density functional theory (DFT) with the B3LYP method combined with the 6-311 ++G(d,p) basis set. As a result of the conformational studies, three stable molecules and the most stable conformer were determined for the both imine oximes. The spectroscopic properties such as vibrational and NMR were calculated for the most stable conformer of the HL (1) and HL (2). The calculation results were applied to simulate infrared spectra of the title compounds, which show good agreement with observed spectra. In addition, the stable three molecules of the both imine oximes have been used to carry out DNA binding and protein docking studies with DNA and protein structures (downloaded from Protein Data Bank) using Discovery Studio 3.5 to find the most preferred binding mode of the ligands inside the DNA and protein cavity.Öğe Sustainable synthetic approaches using [C(16)Im][Oxa] as a flexible organocatalyst and DFT studies toward 3,4-dihydropyrimidinones and benzoxazines(Springer Wien, 2017) Yildirim, Ayhan; Kaya, YunusEasily accessible 1-hexadecyl-1H-imidazol-3-ium oxalate is highly efficient Bronsted type acidic catalyst for the selected multicomponent one-pot reactions. The short reaction times, easy workup procedures, and green metal-free conditions for the reactions make the protocols more advantageous. Further reactions proceeded smoothly in good to excellent yields with high purity. To investigate mechanism of the multicomponent reactions, DFT calculations were performed.
