Yazar "Ucun, F." seçeneğine göre listele

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    Öğe
    A theoretical study on tautomeric structures of 4'-nitroazobenzene-2,4-diol and 4-methyl-4'-nitroazobenzene-2,6-diol compounds
    (Maik Nauka/Interperiodica/Springer, 2014) Karakaya, M.; Ucun, F.
    The goal of this study is to determine the most stable tautomeric forms, and their ground state conformers of 4'-nitroazobenzene-2,4-diol and 4-methyl-4'-nitroazobenzene-2,6-diol compounds. The calculations have shown that the most stable tautomeric forms of the compounds are hydrazo form for 4'-nitroazobenzene-2,4-diol and azo form for 4-methyl-4'-nitroazobenzene-2,6-diol. Besides, the vibrational frequencies, H-1 and C-13 NMR shifts, frontier molecular orbital's energies for the tautomeric forms of the compounds calculated by using density functional theory-B3LYP method with 6-311G(d) basis set were interpreted. All the assignments of the theoretical frequencies were identified by potential energy distribution (PED) analysis. Generally, theoretical spectral results were seen to be in a good agreement with the corresponding experimental data.
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    Öğe
    Calculated hyperfine coupling constants for 5,5-dimethyl-1-pyrroline N-oxide radical products in water and benzene
    (Maik Nauka/Interperiodica/Springer, 2017) Nardali, S.; Ucun, F.; Karakaya, M.
    The optimized structures of some radical adducts of 5,5-dimethyl-1-pyrroline N-oxide were computed by different methods on ESR spectra. As trapped radicals, H, N-3, NH2, CH3, CCl3, OOH in water and F, OH, CF3, CH2OH, OC2H5 in benzene solutions were used. The calculated isotropic hyperfine coupling constants of all the trapped radicals were compared with the corresponding experimental data. The hyperfine coupling constant due to the beta proton of the nitroxide radical was seen to be consist with the McConnel's relation alpha(beta) = B (0) + B (1)cos(2)theta and, to be effected with the opposite spin density of oxygen nucleus bonded to the nitrogen. It was concluded that in hyperfine calculations the DFT(B3PW91)/LanL2DZ level is superior computational quantum model relative to the used other level. Also, the study has been enriched by the computational of the optimized geometrical parameters, the hyper conjugative interaction energies, the atomic charges and spin densities for all the radical adducts.
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    Öğe
    Investigations on Stabilities and Intermolecular Interactions of Different Naphthalene Derivatives Dimers by Using B3LYP and M06-2X Density Functional Calculations
    (Maik Nauka/Interperiodica/Springer, 2014) Karakaya, M.; Cecek, A.; Ucun, F.; Yildiz, M.
    In this paper, the stabilities and hydrogen bond interactions of 4-chloro-1-naphthol,1-hydrox-ynaphthalene and 1,4-dihydroxynaphthalene dimers have been theoretically investigated by means of study on binding energies with nonlocal hybrid three-parameter Lee-Yang-Parr, B3LYP, and M06-class functional calculations. Calculations on dimers aim to provide as a test of the efficacy of M06 calculations for intermolecular interaction calculations and more strongly bound systems. For hydroxyl-and halo-substituted derivatives of naphthalene, total electronic energies, their correction for the zero point vibrational energies with some calculated thermodynamic properties and their relative differences are together in order to discuss the rotamer structures. Static (hyper) polarizabilities and the electric dipole moments, frontier molecular orbital energy gaps and the relationships between them have been interpreted. Generally, they are seen that the calculated geometric parameters and spectral results were in a good agreement with the corresponding experimental data.