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  • Küçük Resim
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    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.
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    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.