Yazar "Yildiz, M." seçeneğine göre listele

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    Öğe
    A study on optimum transition state and tautomeric structures of a bis-heterocyclic monoazo dye
    (Indian Assoc Cultivation Science, 2015) Karakaya, M.; Yildiz, M.
    In this study, possible tautomeric forms and ground state conformers of a bis-heterocyclic monoazo dye, 4-[ethyl 4'-methyl-5'-(phenylcarbamoyl) thiophene-3'-carboxylate-2'-ylazo]-3-methyl-1H-pyrazolin-5-one, have been calculated using density functional theory methods with 6-31G (d) basis set. H-1 and C-13 chemical shifts of tautomeric forms have been calculated. Calculated vibrational frequencies and chemical shifts have been compared with corresponding experimental data. Using time-dependent Hartree-Fock method, electronic absorption spectrum of title compound has been calculated and compared with experimental maximum wavelength data. Quantum Synchronous Transit2 approaches have been used for finding the optimum transition state and tautomeric forms of studied molecule. Calculations have shown that the most probable preferential form of this molecule in ground state is hydrazo-keto form. The calculations of frontier molecular orbitals and first order hyperpolarizability have also confirmed this stability.
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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.
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    Öğe
    Theoretical investigation of phenazine derivatives by using ab initio calculations
    (Indian Assoc Cultivation Science, 2014) Yildiz, M.; Karakaya, M.
    Objective of present study is to compute molecular structures, vibrational frequencies and chemical shifts of phenazine derivatives using density functional theory and Hartree-Fock methods and to compare these results with experimental data. Intramolecular N-Ha <-N interactions have been investigated for stabilization of the molecular conformations. Comparisons of theoretical and experimental data exhibit good correlation confirming the reliability of methods employed in this work. Moreover, frontier orbitals and molecular electrostatic potential have been visualized and calculations of the energy band gaps have been interpreted. According to the results of these investigations, we can say that DFT calculations are significantly stable in electronic structures, spectral, frontier orbitals and electrostatic potential analysis for both the phenazine derivatives.