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    Calculated on 1H and 13C NMR Chemical Shifts of 2,4-Difluorobenzaldehyde Isonicotinoylhydrazone and 2,3-Dichlorobenzaldehyde Isonicotinoylhydrazone with GIAO, IGAIM, and CSGT Models
    (Wiley-Hindawi, 2009) Guenay, N.; Tarcan, E.; Avci, D.; Coemert, H.; Esmer, K.; Atalay, Y.
    The H-1 and C-13 NMR chemical shifts of the 2,4-difluorobenzaldehyde isonicotinoylhydrazone (I) and 2,3-dichlorobenzaidehyde isonicotinoylhydrazone (II) were determined with the help of full spectral analysis. The geometry and electronic structure of the title compounds were investigated at both the ab initio Hartree-Fock and the B3LYP levels with 6-31+G(d,p) basis set. The NMR data were calculated by means of the CIAO, CSGT, and IGAIM methods. All quantum-chemical calculations, including those of NMR data, were performed by ab initio level HF and DFT methods. Excellent agreement between the theoretical and experimental results was found for the HF level H-1 and C-13 chemical shifts. The parameters of molecular geometry and H-1 and C-13 chemical shift values of the title compounds (I, II) in the ground state have been calculated and and compared with corresponding experimental result. (C) 2009 Wiley Periodicals, Inc, Concepts Magn Reson Part A 34A: 297-304, 2009.
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    Molecular structure and vibrational and chemical shift assignments of 3,5-bis-(4-methylbenzoyl)-2,6-bis(4-methylphenyl)-4H-pyran-4-one: A combined experimental and theoretical analysis
    (Elsevier, 2010) Avci, D.; Coemert, H.; Tarcan, E.; Dincer, M.; Atalay, Y.
    The molecular geometry, vibrational frequencies, gauge-including atomic orbital (GIAO) H-1 and C-13 chemical shift values of 3,5-bis-(4-methylbenzoyl)-2,6-bis(4-methylphenyl)-4H-pyran-4-one in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (DFT/B3LYP) with 6-31G(d) basis set. And this structure has been confirmed by IR, C-13 and H-1 spectroscopy. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the experimental bands observed. Also, calculated C-13 and H-1 chemical shift values are compared with the experimental ones. The data of the title compound display significant molecular structure. Moreover, its IR and NMR spectroscopic analysis provide the basis for future design of efficient materials having the pyran core. (C) 2010 Elsevier B.V. All rights reserved.
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    Theoretical Investigation of N-Methyl-N?-(4-nitrobenzylidene) pyrazine-2-carbohydrazide: Conformational Study, NBO Analysis, Molecular Structure and NMR Spectra
    (Polish Acad Sciences Inst Physics, 2015) Gunay, N.; Tamer, O.; Kuzalic, D.; Avci, D.; Atalay, Y.
    The crystal structure determination of the methylated pyrazine-2-carbohydrazide derivative, namely N-methyl-N'-(4-nitrobenzylidene)pyrazine-2-carbohydrazide were optimized to obtain its molecular geometric structure and electronic structures at the Hartree-Fock and density functional theory levels (B3LYP) with 6-311G(d,p) and 6-311++G(d,p) basis sets, using Gaussian 09W programme. The H-1 and C-13 nuclear magnetic resonance chemical shifts of the title molecule were calculated by using the gauge independent atomic orbital, continuous set of gauge transformations and individual gauges for atoms in molecules methods and were also compared with experimental values. The electronic properties high occupied and low unoccupied molecular orbitals energies were calculated and analyzed. Potential energy surface scan, natural population analysis and Mulliken atomic charges were investigated using theoretical calculations. A detailed molecular picture and intermolecular interactions arising from hyperconjugative interactions and charge delocalization of the molecule were analyzed using natural bond orbital analysis.
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    Theoretical studies of molecular structure and vibrational spectra of melaminium acetate acetic acid solvate monohydrate
    (Pergamon-Elsevier Science Ltd, 2010) Pekparlak, A.; Avci, D.; Comert, H.; Atalay, Y.
    The molecular geometry and vibrational frequencies of melaminium acetate acetic acid solvate monohydrate in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-31++G(d,p) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The molecule contains the weak hydrogen bonds of N-H ... O and O-H ... O types, and those bonds are calculated with HF and DFT method. The computed vibrational frequencies were used to determine the types of molecular motions associated with each of the experimental bands observed. In addition, calculated results are related to the linear correlation plot of computed data versus experimental geometric parameters and IR data. (C) 2010 Elsevier B.V. All rights reserved.