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    Synthesis, spectroscopic characterization and DFT calculations of N-Methyl-2-(2′-hydroxyphenyl)benzimidazole derivatives
    (Elsevier, 2016) Saral, Hasan; Ozdamar, Ozgur; Ucar, Ibrahim; Bekdemir, Yunus; Aygun, Muhittin
    1-Methy1-2-(2'-hydroxyphenyl)benzimidazole (1) and 1-Methy1-2-(2'-hydroxy-4'-methylphenyl)benzimidazole (2) compounds have been synthesized and characterized by XRD, IE-MS, FT-IR, UV Vis and H-1, C-13 NMR techniques. The crystal structure of both compounds is stabilized with very strong O-H center dot center dot center dot N hydrogen-bond and pi-pi interactions. In the compound 1, an infinite chain structure with a trans-zigzag type was formed along the crystallographic 11011 direction. Quantum mechanical calculations of energies, geometries, vibrational wavenumbers, NMR and electronic transitions were carried out by DFT using B3LYP functional combined with 6.31G(d,p) basis set. Calculated bond lengths, bond angles and dihedral angles were only slightly different from the experimental ones. The vibrational study was interpreted by means of potential energy distribution (PED). The electronic absorption spectra of the both compounds were predicted by using the time-dependent DFT methods and good agreement was found between the computational and the experimental values. The chemical shifts (H-1 and (1)3C NMR) and isotropic shielding values were calculated by using the gauge-invariant atomic orbital (GIAO) method. The analyses of HOMO and LUMO have been used to explain the charge transfer within the molecule. (C) 2015 Elsevier B.V. All rights reserved.
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    Öğe
    Synthesis, structural and spectroscopic studies of two new benzimidazole derivatives: A comparative study
    (Elsevier, 2017) Saral, Hasan; Ozdamar, Ozgur; Ucar, Ibrahim
    In the present work, structural and spectroscopic studies on 1-Methyl-2-(2'-hydroxy-4'-chlorophenyl) benzimidazole (1) and 1-Methyl-2-(2'-hydroxy-4'-methoxyphenyl)benzimidazole (2), have been carried out extensively by X-ray diffraction, HRMS, UV-Vis, FT-IR and H-1 and C-13 NMR spectroscopy. The crystal structure of both compounds is stabilized by O-H center dot center dot center dot N hydrogen bond and pi-pi interactions. Contrary to compound 1, the skeleton of compound 2 is considerably deviated from the planarity probably caused by intermolecular hydrogen bonding. The experimental results were compared to the theoretical ones, obtained at DFT level. Ground state geometry, electronic structure, vibrational and NMR spectra have been performed using the B3LYP functional with the 6-31 G(d,p) basis set. It was observed that the bond distances and angles in the both compounds were in good with those of the experiment. The energetic behaviors of the both compounds in methanol solvent were examined using by time-dependent DFT (TD-DFT) method by applying the polarizable continuum model (PCM). Isotropic chemical shifts (C-13 and H-1 NMR) were calculated using the gauge-invariant atomic orbital (GIAO) method. The HOMO and LUMO analyses were used to elucidate information regarding charge transfer within the molecule. (C) 2016 Elsevier B.V. All rights reserved.