Yazar "Senel, Ismet" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • [ X ]
    Öğe
    Experimental and density functional theory (DFT) studies on (E)-2-Acetyl-4-(4-nitrophenyldiazenyl) phenol
    (Elsevier, 2011) Yazici, Serap; Albayrak, Cigdem; Gumrukcuoglu, Ismail; Senel, Ismet; Buyukgungor, Orhan
    A suitable single crystal of (E)-2-Acetyl-4-(4-nitrophenyldiazerwl) phenol, formulated as C14H11N3O4, (I), reveals that the structure is adopted to its E configuration and molecules are linked by C-H center dot center dot center dot O hydrogen bonds. The title compound which has been characterized by IR, UV and single crystal X-ray diffraction analysis at 150K crystallizes in the monoclinic space group C 2/c with a= 12.8640(8) angstrom, b = 7.3264(3) angstrom, c = 26.9330(17) angstrom, alpha = 90 degrees, beta = 93.052(5)degrees, gamma = 90 degrees, Z = 7. The molecular structure and geometry have also been optimized using B3LYP density functional theory method employing the 6-31G (d, p) basis set. To acquire lowest- energy molecular conformation of the title molecule, the selected torsion angle is varied every 10 and molecular energy profile is calculated from -180 degrees to +180 degrees. Furthermore, the molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis, nonlinear optical properties (NLO) and thermodynamic properties for the title molecule are also described from the computational process. (c) 2010 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    Experimental and quantum chemical computational study of (E)-1-[5-(3,4-dimethylphenyldiazenyl)-2-hydroxyphenyl]ethanone
    (Pergamon-Elsevier Science Ltd, 2012) Yazici, Serap; Albayrak, Cigdem; Gumrukcuoglu, Ismail Erdem; Senel, Ismet; Buyukgungor, Orhan
    In this work, the azo dye, (E)-1-[5-(3,4-dimethylphenyldiazenyl)-2-hydroxyphenyl]ethanone, has been synthesized and characterized by IR. and X-ray single-crystal determination. In the theoretical calculations, the stable structure geometry of the isolated molecule in gas phase was investigated under the framework of the density functional theory (B3LYP) with 6-31G (d, p). To designate lowest energy molecular conformation of the title molecule, the selected torsion angle was varied every 10 degrees and the molecular energy profile was calculated from - 180 degrees to +180 degrees. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis, and thermodynamic properties were described from the computational process. In addition to these calculations, we were investigated solvent effects on the nonlinear optical properties (NLO) of the title compound. (C) 2012 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    The proton transfer process observed in the structure analysis and DFT calculations of (E)-2-ethoxy-6-[(2-methoxyphenylimino)methyl]phenol
    (Springer/Plenum Publishers, 2010) Petek, Hande; Albayrak, Cigdem; Odabasoglu, Mustafa; Senel, Ismet; Buyukgungor, Orhan
    The crystal and molecular structures of an o-hydroxy Schiff base derivative, (E)-2-ethoxy-6-[(2-methoxyphenylimino)methyl]phenol, have been determined by single crystal X-ray diffraction analyses at 296 and 100 K. The results from temperature-dependent structural analysis regarding the tautomeric equilibrium of the compound were interpreted with the aid of quantum chemical calculations. To clarify the tautomerization process and its effects on the molecular geometry, the gas-phase geometry optimizations of two possible tautomers of the title molecule, its OH and NH form, were achieved using DFT calculations with B3LYP method by means of 6-31 + G(d,p) basis set. In order to describe the potential barrier belonging to the phenolic proton transfer, nonadiabatic Potential Energy Surface (PES) scan was performed based on the optimized geometry of the OH tautomeric form by varying the redundant internal coordinate, O-H bond distance. The Harmonic Oscillator Model of Aromaticity (HOMA) indices were calculated in every step of the scan process so as to express the deformation in the aromaticities of principal molecular moieties of the compound. The results show that there is a dynamic equilibrium between the aromaticity level of phenol and chelate ring and furthermore pi-electron coupling affecting overall molecule of the title compound. Charge transfer from phenol ring to pseudo-aromatic chelate ring increases with increasing temperature, whereas pi-electron transfer from chelate ring to anisole ring is decreased as temperature increases. The most strength intramolecular H-bonds are observed for conformers close to transition state.