Yazar "Atalay, Yusuf" seçeneğine göre listele

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    Ab initio Hartree-Fock calculations on linear and second-order nonlinear optical properties of new acridine-benzothiazolylamine chromophores
    (Springer, 2008) Avci, Davut; Comert, Hueseyin; Atalay, Yusuf
    The calculation of optimized molecular structure and molecular hyperpolarizability of four new acridine-benzothiazolylamine chromophores (1-4) [2-nitro-6-(piperid-1-yl) acridine (1), 6-(benzothiazol-2-yl-amino)-2-nitro-acridine (2), 6-(6-ethylcarboxylate-benzothiazol-2-yl-amino)-2-nitroacridine (3), 6-(6-(beta-hydroxyethyl-benzothiazol-2-yl-amino)-2-nitroacridine (4)] have been investigated using ab initio methods. Ab initio optimization were performed at the Hartree-Fock level using STO-3G basis set. The first hyperpolarizabilities have been calculated at the Hartree-Fock method with 6-31G and 6-311G basis sets using Gaussian 98W. In general, the first hyperpolarizability is dependent on the choice of method and basis set. To understand this phenomenon in the context of molecular orbital picture, we examined the frontier molecular orbital energies of all the molecules by using HF/6-31G, 6-311G levels. The polarizability, anisotropy of polarizability and ground state dipole moment of all the molecules have also been calculated. These acridine-benzothiazolylamine chromophores display significant second-order molecular nonlinearity, beta (60.2-137.0x10(-30) esu) and provide the basis for future design of efficient nonlinear optical materials having the acridine-benzothiazolylamine core.
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    DFT Calculations on the Molecular Structure, Vibrational and Chemical Shift Assignments of 4-Allyl-2-(morpholin-4-ylmethyl)-5-(pyridin-4-yl)-2, 4-Dihydro-3H-1,2,4-Triazole-3-Thione
    (Springer Heidelberg, 2011) Avci, Davut; Atalay, Yusuf; Comert, Huseyin; Dincer, Muharrem
    The molecular geometry, vibrational frequencies, gauge including atomic orbital (GIAO) H-1 and C-13 chemical shift values and several thermodynamic parameters of 4-allyl-2-(morpholin-4-ylmethyl)-5-(pyridin-4-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione in the ground state were calculated using density functional methods (BLYP and B3LYP) with the 6-31G(d) basis set. The results of the optimized molecular structure are given and compared with experimentally obtained X-ray diffraction. The computed vibrational frequencies were used to determine the types of molecular motions associated with each of the experimental bands observed. Vibrational mode assignments of the title compound were carried out using a total energy distribution calculation. The calculated H-1 and C-13 chemical shift values are compared with the experimental values. The molecular frontier orbital energies of the title compound were calculated using the BLYP and B3LYP/6-31G( d) levels. The obtained data for the title compound provided its molecular structure, while the IR and NMR analyses provide a basis for the future design of efficient materials containing a 1,2,4-triazole core.
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    Synthesis, spectroscopic characterization and DFT calculations on N-(Phenylsulfonyl)-L-asparagine (NPLAS): A potential nonlinear optical material
    (Elsevier Gmbh, 2016) Gunay, Nergin; Tamer, Omer; Kuzalic, Dilek; Avci, Davut; Atalay, Yusuf
    The N-(Phenylsulfonyl)-L-asparagine (NPLAS), which is a potential nonlinear optical material, was synthesized and its geometric structure was optimized to obtain its geometric parameters, vibration frequencies and electronic structures at Hartree-Fock (HF) and B3LYP level of density functional theory (DFT) with 6-311 + +G(d,p) basis set, using Gaussian 09W program. The H-1 and C-13 nuclear magnetic resonance (NMR) chemical shifts of the title molecule were calculated by using the gauge independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and individual gauges for atoms in molecules (IGAIM) methods and were also compared with experimental values. The electronic properties HOMO and LUMO energies were calculated and analyzed. Potential energy surface scan, natural population analysis (NPA) and Mulliken's atomic charges were also investigated using DFT and HF models. A detailed molecular picture and intermolecular interactions arising from hyperconjugative interactions and charge delocalization of the molecule were analyzed using natural bond orbital (NBO) analysis. (C) 2016 Elsevier GmbH. All rights reserved.
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    Theoretical Investigation of 6-(3,3,4,4,4-Pentafluoro-2-Hydroxy-1-Butenyl)-2,4-Dimethoxy-Pyrimidine Molecule
    (Springer Heidelberg, 2014) Pir, Hacer; Gunay, Nergin; Avci, Davut; Tamer, Omer; Tarcan, Erdogan; Atalay, Yusuf
    In this paper, we report a theoretical study on conformational, natural bond orbital (NBO) and nonlinear optical (NLO) analysis, molecular geometry, vibrational frequencies, H-1 and C-13 NMRchemical shifts values of the title molecule in the ground state calculated with the help of Density Functional Theory (DFT-B3LYP/6-311++G(d,p)) and Hartree-Fock (HF/6-311++G(d,p)) methods. In this study, conformational analysis has been calculated using Hartree-Fock (HF) at 6-31G level for the title molecule. The existence of intramolecular hydrogen bonding interactions, and various molecular parameters has been investigated by means of the natural bonding orbital (NBO) analysis. The optimized geometric parameters, vibrational frequencies, H-1 and C-13 NMR chemical shifts values are compared with experimental values of the investigated molecule. To understand this phenomenon in the context of molecular orbital picture, we examined the highest occupied molecule energy level (E-HOMO), the lowest unoccupied molecule energy level (E-LUMO), the energy difference (Delta E) between E-HOMO and E-LUMO, electronegativity (X), hardness (eta) and softness (S) calculated by HF/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels. The calculated HOMO and LUMO energies show that the charge transfer occurs within the molecule. It has also been calculated thermodynamic parameters, molecular surfaces, Mulliken charges and atomic polar tensor-based charges of the investigated molecule. Finally, the calculated results were applied to simulate infrared and NMR spectra of the investigated molecules which showed good agreement with experimental ones.
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    A THEORETICAL STUDY ON A CHIRAL COORDINATION OF SILVER(I) WITH SACCHARINATE AND PYRIDINE [Ag(sac)(py)]
    (Springer Heidelberg, 2010) Pekparlak, Asli; Avci, Davut; Atalay, Yusuf; Celik, Tuncer
    The molecular geometry, the normal mode frequencies, and corresponding vibrational assignments of chiral coordination monomer silver(I) with saccharinate and pyridine [Ag(sac)(py)] in the ground state were performed by HF and B3LYP levels of theory using the LanL2DZ basis set. The optimized bond lengths and bond angles are in good agreement with the x-ray data. The vibrational spectra of the title compound, which is calculated by HF and DFT methods, reproduces vibrational wave numbers and intensities with an accuracy which allows reliable vibrational assignments. The title compound [Ag(sac)(py)] has been studied theoretically in the 4000-200 cm-1 region and the assignment of all the observed bands was made. The analysis of the infrared spectra indicates that there are some structure-spectra correlations. Also, the molecular frontier orbital energies of the title compound have been calculated using HF and B3LYP/ LanL2DZ levels.