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Öğe EPR Study of Gamma-Irradiated Single Crystal 4-Phenylsemicarbazide(Pergamon-Elsevier Science Ltd, 2010) Sayın, U.; Türkkan, E.; Dereli, Ö.; Yüksel, H.; Birey, M.Single crystals of 4-phenylsemicarbazide (4PSC) were investigated using an electron paramagnetic resonance (EPR) technique, with gamma irradiation of the crystals at different orientations in the magnetic field between temperatures of 120 and 450 K, and the spectra were found to be temperature independent. Taking into consideration the chemical structure and the experimental spectra of the irradiated single crystal 4PSC, we assumed that one or more paramagnetic species were produced, each having an unpaired electron delocalized in the phenyl ring. Pursuant to this assumption, six possible radicals were modeled using the B3LYP/6-311+G(d) level of density-functional theory. EPR parameters were calculated for these modeled radicals using the B3LYP method and TZVP basis set. The calculated hyperfine coupling constants were used as starting points for simulations. The experimental and simulated spectra for each of the three crystallographic axes were well matched for the modeled radical R6. We thus identified the R6 (C6H5NH) radical as a paramagnetic species produced in 4PSC. The experimental g-factor and hyperfine coupling constants of the C6H5NH radical were found to be anisotropic, with the average values g = 2.00431, a(NH)(N(8)) = 8.85 G, a(NH)(H(9)) = 16.85 G, a(o,p)(H(14,16,20)) = 6.47 G, and a(m)(H(18,19)) = 2.80 G.Öğe Structural, Vibrational and Hyperpolarizability Calculation of (E)-2-(2-Hydroxybenzylideneamino)-3-Methylbutanoic Acid(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Subashchandrabose, S.; Saleem, H.; Erdoğdu, Y.; Dereli, Ö.; Thanikachalam, V.; Jayabharathi, J.The (E)-2-(2-hydroxybenzylideneamino)-3-methylbutanoic acid (E)-2HBAMBA was synthesized. The FT-IR, FT-Raman and UV-vis spectra have been recorded and characterized. Theoretical wavenumbers along with IR and Raman intensities were calculated using B3LYP/6-31G(d,p) level and total energy distribution (TED) of the various normal mode of vibrations were also studied. The conformational analysis was performed for a stable conformer by selecting the dihedral angles and the optimized bond parameters were calculated for the stable structure. Effect of intramolecular interactions is calculated by changing the orientation of hydroxyl hydrogen. To know the charge transfer while changing the hydroxyl group hydrogen orientation, the NBO analysis was performed. Using the same level of calculation, the electronic charge transfers were calculated and compared.Öğe Study on Molecular Structure and Vibrational Spectra of (Triphenylphosphoranylidene) Acetaldehyde Using DFT: A Combined Experimental and Quantum Chemical Approach(ELSEVIER, 2012) Dereli, Ö.; Erdoğdu, Y.; Gullüoglu, M. T.In the present study, an exhaustive conformational search of the (triphenylphosphoranylidene) acetaldehyde has been performed. The FT-IR spectrum of this compound was recorded in the region 4000-400 cm(-1). The FT-Raman spectrum was also recorded in the region 3500-50 cm(-1). Vibrational frequencies of the title compound have been calculated by B3LYP method using 6-311++G(d,p) basis sets. The calculated geometric parameters and vibrational frequencies were analyzed and compared with obtained experimental results.Öğe Vibrational (FT-IR and FT-Raman) Spectral Investigations of 7-Aminoflavone with Density Functional Theoretical Simulations(TAYLOR & FRANCIS LTD, 2012) Erdoğdu, Y.; Dereli, Ö.; Sajan, D.; Joseph, L.; Ünsalan, O.; Güllüoğlu, M. T.FT-Raman and FT-IR spectra of the 7-aminoflavone have been recorded and analysed. The detailed interpretation of the vibrational spectra has been carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology. The various intramolecular interactions that are responsible for stabilisation of the molecule were revealed by natural bond orbital analysis. The obtained vibrational wavenumbers and optimised geometric parameters were observed to be in good agreement with the experimental data. The carbonyl stretching vibrations have been lowered due to conjugation and hydrogen bonding in the molecules.Öğe Vibrational Spectral and Quantum Chemical Investigations of Tert-Butyl-Hydroquinone(ELSEVIER, 2012) Dereli, Ö.; Erdoğdu, Y.; Güllüoğlu, M. T.; Türkkan, E.; Özmen, A.; Sundaraganesan, N.The Fourier transform infrared (FT-IR) and micro-Raman spectra of tert-butyl-hydroquinone were recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1), respectively. Conformational space was scanned with molecular mechanic simulations. All other calculations were performed by B3LYP/6-311G++(d,p) level of theory. The molecular structure and vibrational frequencies of the title compound were calculated and compared with experimental spectra. Theoretical vibrational spectra of the title compound were interpreted by means of TEDs. Predicted electronic absorption spectrum of tert-butylhydroquinone from TD-DFT calculation was analyzed and compared with the experimental UV-visible spectrum.
