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Öğe Anticancer, antimicrobial, spectral, voltammetric and DFT studies with Cu(II) complexes of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its N(4)-substituted derivatives(ELSEVIER SCIENCE SA, 2017) Turkkan, Ercan; Sayin, Ulku; Erbilen, Nesibe; Pehlivanoglu, Suray; Erdogan, Gokce; Tasdemir, Halil Ugur; Saf, Ahmet OzgurNew copper complexes of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its N(4)-substituted derivatives were synthesized and characterized by theoretical DFT studies and experimental UV-Vis, FT-IR, EPR spectral analysis, cyclic voltammetry, magnetic susceptibility and conductivity measurements. The DFT calculation results have been used to predict and interpret the experimental results. The geometric parameter G within the range of 7.61-7.86 for all complexes confirms the mononuclear nature of the complexes. The EPR, UV-Vis, DFT studies and obtained bonding parameters show that all the complexes have square planar geometry and their M-L bonds have strong ionic and some in-plane a-bond character. In addition, the experimental and DFT studies showed that HOMO and LUMO energy levels of the complexes may present good electron transporting properties. Also, the investigated Cu(II) complexes were tested for biological activity, proving both in vitro antibacterial and anticancer activity. The complexes exhibited antibacterial activity against Gram positive bacteria S. aureus while exhibiting no activities against gram negative bacteria E. toll and S. gallinarum. The f parameters obtained experimentally by EPR support the antimicrobial activity properties results of the complexes. The evaluations of potential anticancer activity of these complexes were carried out against highly metastatic MDA-MB-231 breast adenocarcinoma cell line by MTT assay. Our results suggest that all tested copper complexes have high cytotoxic effects with the range of 1.76-3.53 mu M IC50 values in vitro. These copper complexes could be considered as potential anticancer agents to counteract drug resistance of metastatic cancer cells. (C) 2016 Elsevier B.V. All rights reserved.Öğe Determination of radicals produced by irradiation in cholesteryl octanoate single crystals using esr technique(GAZI UNIV, 2016) Sayin, Ulku; Buyukcelebi, Sami; Ozmen, AyhanIn this study, the radicals produced by gamma irradiation was determined using ESR technique in cholesteryl octanoate (C35H60O2), a cholesterol ester, which has medical importance. The samples that crystallized in ethanol solution were irradiated with 60Co-source. The molecules that have diamagnetic property become paramagnetic after irradiation. ESR spectra were recorded in different microwave powers and different temperatures at 10 degrees intervals in the magnetic field applied along each of the perpendicular axes using JEOL JESFA-300 X-band ESR spectrometer located in Selcuk University Advanced Technology Research and Application Center. By considering the chemical structure and ESR spectra of Cholesteryl octanoate molecule, it was identified that radiation produced stable and long lived radical, R-CH 3 alpha CH beta CH2 gamma in the sample. The hyperfine splitting and spectroscopic splitting values which have anisotropic property due the location of crystal in the magnetic field were obtained. In addition, simulations were made for identified radical and a good agreement was found with the experimental spectra.Öğe Effects of gamma irradiation on the single crystal ergosterol: An EPR study(ELSEVIER SCIENCE BV, 2012) Sayin, Ulku; Dereli, Omer; Turkkan, ErcanSingle crystals of ergosterol were investigated by Electron Paramagnetic Resonance (EPR) technique, with gamma irradiation of the crystals at different orientations in the magnetic field between temperatures of 120 and 380 K, and the spectra were found to be slightly dependent on temperature. Because of the importance of ergosterol it is important to determine the irradiation effects on this molecule. Taking into consideration the chemical structure and the experimental spectra of the irradiated single crystal ergosterol, we found that two paramagnetic species which were labeled as radical A. (center dot)CH2(alpha)H(beta), and radical B-1 (CH alpha H beta H gamma H sigma)-C-center dot, were produced in the host crystal. The EPR parameters; spectroscopic splitting factor, g, and hyperfine coupling constant, a, were determined for each radical. (C) 2011 Elsevier B.V. All rights reserved.Öğe An electron paramagnetic resonance and density-functional theory study on the methyl isotropic hyperfine coupling constants in gamma-irradiated 2,6-di-tert-butyl-4-methylphenol(TAYLOR & FRANCIS LTD, 2013) Turkkan, Ercan; Dereli, Omer; Sayin, Ulku; Tapramaz, RecepSingle crystal of gammairradiated 2,6-di-tert-butyl-4-methylphenol (BHT) was investigated using an electron paramagnetic resonance (EPR) technique at different orientations in the magnetic field at room temperatures. Taking into consideration the chemical structure and the experimental spectra of the irradiated single crystal of BHT, we assumed that one phenoxyltype paramagnetic species was produced having an unpaired electron localized at the methyl fragment side of the phenyl ring. Depending on this assumption, one possible radical was modeled using the B3LYP/6-311+G(d) level of density-functional theory. EPR parameters were calculated for these modeled radical using the B3LYP/TZVP and B3LYP/EPR-III level. The averaged value of isotropic hydrogen hyperfine coupling constants of rotating methyl functional group of phenoxyl radical is calculated for the first time. Theoretically calculated values of the modeled radical are in reasonably good agreement with the experimental data determined from the spectra (differences in averaged coupling constant values smaller than 5%, and differences in isotropic g values fall into 1ppt).Öğe EPR analysis of gamma irradiated single crystal cimetidine(ELSEVIER SCIENCE BV, 2013) Sayin, UlkuThe magnetic properties of gamma irradiated single crystal cimetidine were investigated between temperatures of 123 K and 418 K and between microwave power of 0.01 mW and 150 mW by electron paramagnetic resonance. Magnetic field orientation in each of the three perpendicular axes, microwave power, and temperature dependence of the EPR spectra has led to more than one radical being produced by gamma irradiation in the host crystal. The distinctive radical was attributed to being a ring type radical; however, the other radicals could not be identified because of the superimposition. The EPR parameters of the ring type radical were determined to be: a(H-alpha)(av) = 2.42 mT, a(N-alpha)(av) = 0.62 mT, a(H-beta)(av) = 1.08 mT, a(H-gamma)(av) = 0.2 mT, a(N-beta)(av) = 0.3 mT, and (g)(av) = 2.0030, respectively. (C) 2012 Elsevier B.V. All rights reserved.Öğe EPR investigation of gamma irradiated single crystal guaifenesin: A combined experimental and computational study(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Tasdemir, Halil Ugur; Sayin, Ulku; Turkkan, Ercan; Ozmen, AyhanGamma irradiated single crystal of Guaifenesin (Glyceryl Guaiacolate), an important expectorant drug, were investigated with Electron Paramagnetic Resonance (EPR) spectroscopy between 123 and 333 K temperature at different orientations in the magnetic field. Considering the chemical structure and the experimental spectra of the gamma irradiated single crystal of guaifenesin sample, we assumed that alkoxy or alkyl-type paramagnetic species may be produced by irradiation. Depending on this assumption, eight possible alkoxy and alkyl-type radicals were modeled and EPR parameters of these modeled radicals were calculated using the B3LYP/6-311+ +G(d,p)-level of density functional theory (DFT). Theoretically calculated values of alkyl-type modeled radical(R3) are in good agreement with experimentally determined EPR parameters of single crystal. Furthermore, simulation spectra which are obtained by using the thepretical initial values are well matched with the experimental spectra. It was determined that a stable C alpha H2 alpha C beta H beta C gamma H2 gamma (R3) alkyl radical was produced in the host crystal as a result of gamma irradiation. (C) 2015 Elsevier Ltd. All rights reserved.Öğe EPR study of gamma-irradiated 2-Bromo-4 '-methoxyacetophenone single crystals(TAYLOR & FRANCIS LTD, 2016) Tasdemir, Halil Ugur; Turkkan, Ercan; Sayin, Ulku; Ozmen, AyhanThe gamma-irradiated single crystals of 2-Bromo-4'-methoxyacetophenone (2B4MA) were investigated using electron paramagnetic resonance (EPR) technique. Density-functional theory calculations were employed to investigate and identify the radicals that have been assumed to be formed upon irradiation of 2B4MA single crystals. The EPR spectra of 2B4MA were recorded at different orientations in the magnetic field at room temperature. Taking into account the chemical structure and experimental spectra of irradiated single crystal of 2B4MA, it was assumed that at least two different radicals were produced in the sample. Following this assumption, six possible radicals were modeled and EPR parameters were calculated by using the DFT, B3LYP/6-311+G(d), for the modeled radicals individually. The calculated hyperfine coupling constants and g-tensors were used as initial values for simulation studies. The three crystallographic axes on the simulated spectra were well matched with experimental spectra for the two modeled radicals. Thus, we identified the R1 type radical and R4 type radical as paramagnetic species produced in gamma-irradiated 2B4MA.Öğe ESR analysis of kumyer location archeological ceramics and determination of suitability for ESR dating(GAZI UNIV, 2017) Bakkal, Gamze; Sayin, Ulku; Isik, Ilker; Ozmen, Ayhan; Kilic, Hamdi SukurIn this study paramagnetic centers in quartz minerals of Kumyer Location archeological samples were identified using Electron Spin Resonance (ESR) technique. ESR spectra were recorded at different microwave powers and various spectrometer temperatures with JEOL JESFa-300 X-band ESR spectrometer located in Selcuk University Advanced Technology Research and Application Center (ILTEK). It was determined that there is Al, Ti-Li, Ti-H and Ge paramagnetic centers which were produced by natural radiation in quartz minerals of ceramic samples and ESR parameters of these centers were measured. In order to determine whereas Kumyer Location archeological ceramics are suitable samples for ESR dating, ESR spectra of artificial irradiated samples recorded at 300K and 81K temperature were analyzed. Thermal stability of Al and Ti centers were determined by isochronal annealing experiment of artificial irradiated samples. As a result of experimental studies, it was determined that quartz minerals of Kumyer location archeological ceramic samples have stable and radiation dependent paramagnetic centers thus, these samples can be used for ESR dating.Öğe ESR analysis of natural and gamma irradiated coriander (Coriandrum sativum L.) seeds(TAYLOR & FRANCIS LTD, 2017) Sezer, M. Ozgur; Kaplan, Necati; Sayin, UlkuElectron spin resonance ( ESR) is a powerful technique to detect radicals trapped in cellulosic food products and has been suggested as a useful method for identification of irradiated herbal foodstuffs. Coriander spice which has important medicinal properties was investigated using ESR spectroscopy. Radicals in natural and irradiated coriander samples were determined at room temperature. ESR spectra of natural sample were characterized by a single central signal with g = 2.0045 value and gamma irradiation produced satellite peaks attributed to cellulose- like radical which is used as a marker for detection of irradiated cellulosic plant products. The spectroscopic splitting values of radicals were determined. Dose dependency and stability of this center were analyzed by dose response and kinetic measurements. The reported results about activation energy, thermal life time and dose response relationship of the cellulose- like radical accurately prove that ESR can be used for identification of irradiated coriander spice seeds.Öğe ESR Characterization of Two Oxovanadium (IV) Schiff Base Complexes Derived from Tris(2-aminoethyl)amine(TAYLOR & FRANCIS INC, 2012) Sahin, Mustafa; Kocak, Nuriye; Sayin, Ulku; Yilmaz, MustafaThe compounds, C21H27N4O3(L-1) and C21H27N7(L-2), is a tripodal Schiff base that was obtained from the reaction of tris(2-aminoethyl)amine (tren) and furan-2-carbaldehyde and pyrole-2-carbaldehyde. The tripodal Schiff bases and their oxovanadium complexes have been characterized on the basis of the results of the elemental analysis, magnetic susceptibility measurements and spectroscopic studies FT-IR, H-1-NMR, UV-Vis, ESR, magnetic moment and thermal analysis (TGA). Job's method of continuous variation shows 3: 2 metal to ligand ratio.Öğe Experimental and theoretical research on -irradiated 7-methoxy-4-methylcoumarin powder through EPR and DFT methods(TAYLOR & FRANCIS LTD, 2018) Sarikaya, Ebru Karakas; Ates, Levent; Sayin, Ulku; Ozmen, Ayhan; Dereli, OmerIn this paper, the effects of gamma irradiation on 7-Methoxy-4-methylcoumarin (7M4MC) molecule, an essential coumarin derivative, which has an inherent variety of biological activities, therapeutic properties and industrial usage were examined. For this purpose, the sample was irradiated with Co-60-gamma ray source for about 100kGy total doses. Theoretical calculations were performed using GAUSSIAN03 program for the possible radicals that were modeled from two stable conformations with lowest energies. In order to get well-resolved spectra and to determine the radical identity experimentally, EPR spectra of the irradiated 7M4MC sample were recorded at several spectrometer conditions. By considering the molecular structure and EPR spectra, alkyl-type radical was assumed to be formed by gamma irradiation. To support the estimations, simulations were done using theoretical EPR parameters as an initial value. The experimental spectra were well matched with the sum of simulated spectra obtained from two same type modeled radicals of two different conformations. As a result of experimental estimations and theoretical calculations, radiation-induced radicals were identified as two neutral alkyl radicals, originated from two stable conformations.Öğe The Importance of Pre-Annealing Treatment for ESR Dating of Mollusc Shells: A Key Study for Ismil in Konya Closed Basin/Turkey(AMER INST PHYSICS, 2018) Ekici, Gamze; Sayin, Ulku; Aydin, Hulya; Isik, Mesut; Kapan, Sevinc; Demir, Ahmet; Engin, BirolIn this study, Electron Spin Resonance (ESR) spectroscopy is used to determine the geological ages of fossil mollusc shells systematically collected from two different geological splitting at Ismil Location (37.72769 degrees N, 33.17781 degrees E) in eastern part of Konya. According to the assessment of obtained ESR ages, the importance of pre-annealing treatment emphasize in the case of g=2.0007 dating signal is overlapped with the other signals arisen from short lived radicals that cause the wrong age calculation. To overcome this problem, the samples are pre-annealed at 180 degrees C for 16 minutes and, in this case ESR ages are recalculated for g=1.9973 dating signal. Dose response curves are obtained using 1.9973 signals after pre-annealing treatments for each samples. ESR ages of samples are obtained in the range of 138 +/- 38 ka and 132 +/- 30 ka (Upper Pleistocene) according to the Early Uranium Uptake model and the results are in good agreement with the estimated ages from stratigraphic and paleontological correlation by geologists. Thus, it is suggested that especially in the case of g=2.0007 dating signal cannot been used due to superimposition case, the signal with 1.9973 g value can be used for dating after pre-annealing treatment. The results reports the first ESR ages on shells collected from Ismil Location and highlight the importance of pre-annealing treatment. This study is supported by TUBITAK 114Y237 research project.Öğe Magnetic properties of gamma irradiated single crystals of cholesteryl chloride: An EPR study(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Sayin, Ulku; Yuksel, Huseyin; Birey, MehmetThe cholesteryl chloride compound has been irradiated with Co-60-gamma ray at room temperature. The radical produced by gamma irradiation has been investigated in the range of temperatures 123-450 K for different orientations of the crystal in a magnetic field by electron paramagnetic resonance (EPR). Radiation damage center was attributed to radical CH alpha CH2 beta CH2 gamma. The g factor and hyperfine coupling constants have slight dependency on temperature and evident dependency on the orientation of the magnetic field. Determined g factor and hyperfine coupling constants for the radical CH alpha CH2 beta CH2 gamma, were found to be anisotropic with the average values g(av) = 2.003222,(a(CH alpha))(av) = 16.82G and (a(CH2 beta))(av) = 23.94G measured in all axes and (a(CH2 gamma))(av) = 8G, which was measured only in one axis. (C) 2011 Elsevier Ltd. All rights reserved.
