Browsing by Author "Sas, EB"

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    FT-IR, FT-Raman, NMR and UV-Vis spectra and DFT calculations of 5-bromo-2-ethoxyphenylboronic acid (monomer and dimer structures)
    Sas, EB; Kose, E; Kurt, M; Karabacak, M
    In this study, the Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of 5-bromo-2-ethoxyphenylboronic acid (5Br2EPBA) are recorded in the solid phase in the region 4000400 cm(-1) and 3500-10 cm(-1), respectively. The H-1, C-13 and DEPT nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The UV-Vis absorption spectrum of 5Br2EPBA is saved in the range of 200-400 nm in ethanol and water. The following theoretical calculations for monomeric and dimeric structures are supported by experimental results. The molecular geometry and vibrational frequencies in the ground state are calculated by using DFT methods with 6-31 G(d,p) and 6-311 G(d,p) basis sets. There are four conformers for the present molecule. The computational results diagnose the most stable conformer of 5Br2EPBA as Trans-Cis (TC) form. The complete assignments are performed on the basis of the total energy distribution (TED) of vibrational modes, calculated with scaled quantum mechanics (SQM) method in parallel quantum solutions (PQS) program. The H-1 and C-13 NMR chemical shifts of 5Br2EPBA molecule are calculated by using the Gauge Invariant Atomic Orbital (GIAO) method in DMSO and gas phase for monomer and dimer structures of the most stable conformer. Moreover, electronic properties, such as the HOMO and LUMO energies (by TD-DFT and CIS methods) and molecular electrostatic potential surface (MEPs) are investigated. Stability of the molecule arising from hyper-conjugative interactions, charge delocalization is analyzed using natural bond orbital (NBO) analysis. Nonlinear optical (NLO) properties and thermodynamic features are presented. All calculated results are compared with the experimental data of the title molecule. The correlation of theoretical and experimental results provides a detailed description of the structural and physicochemical properties of the title molecule. (C) 2014 Elsevier B.V. All rights reserved.
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    Spectroscopic studies on 9H-carbazole-9-(4-phenyl) boronic acid pinacol ester by DFT method
    Sas, EB; Kurt, M; Can, M; Horzum, N; Atac, A
    9H-Carbazole-9-(4-phenyl) boronic acid pinacol ester (9-CPBAPE) molecule was investigated by FT-IR, Raman, UV vis, H-1 and C-13 NMR spectra. FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. H-1, C-13 NMR and UV-vis spectra were recorded in dimethyl sulfoxide (DMSO) solution. The results of theoretical calculations for the spectra of the title molecule were compared with the experimental spectra. The highest occupied molecular orbital (HOMO) the lowest unoccupied molecular orbital (LUMO) and molecular electrostatic potential (MEP) analyses were performed. The theoretical calculations for the molecular structure and spectroscopic studies were performed with DFT (B3LYP) and 6-311G (d,p) basis set calculations using the Gaussian 09 program. The total (TDOS), partial (PDOS) density of state and overlap population density of state (OPDOS) diagrams analyses were performed using GaussSum 2.2 program. (C) 2016 Elsevier B.V. All rights reserved.
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    Experimental (FT-IR, FT-Raman, UV-Vis, 1H and 13C NMR) and computational (density functional theory) studies on 3-bromophenylboronic acid
    Karabacak, M; Kose, E; Atac, A; Sas, EB; Asiri, AM; Kurt, M
    Structurally, boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent (i.e., C-Br bond) and two hydroxyl groups to fill the remaining valences on the boron atom. We studied 3-bromophenylboronic acid (3BrPBA); a derivative of boronic acid. This study includes the experimental (FT-IR, FT-Raman, H-1 and (1)3C NMR, UV-Vis) techniques and theoretical (DFT-density functional theory) calculations. The experimental data are recorded, FT-IR (4000-400 cm(-1)) and FT-Raman spectra (3500-10 cm(-1)) in the solid phase. H-1 and C-13 NMR spectra are recorded in DMSO solution. UV-Vis spectrum is recorded in the range of 200-400 nm for each solution (in ethanol and water). The theoretical calculations are computed DFT/B3LYP/6-311++G(d,p) basis set. The optimum geometry is also obtained from inside for possible four conformers using according to position of hydrogen atoms after the scan coordinate of these structures. The fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and parallel quantum solutions (PQS) program. H-1 and C-13 NMR chemical shifts are racked on by using the gauge-invariant atomic orbital (GIAO) method. The time-dependent density functional theory (TD-DFT) is used to find HOMO and LUMO energies, excitation energies, oscillator strengths. The density of state of the studied molecule is investigated as total and partial density of state (TDOS and PDOS) and overlap population density of state (OPDOS or COOP) diagrams have been presented. Besides, frontier molecular orbitals (FMOs), molecular electrostatic potential surface (MEPs) and thermodynamic properties are performed. At the end of this work, the results are ensured beneficial for the literature contribution. (C) 2014 Elsevier B.V. All rights reserved.
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    DFT calculations and experimental FT-IR, FT-Raman, NMR, UV-Vis spectral studies of 3-fluorophenylboronic acid
    Karabacak, M; Kose, E; Sas, EB; Kurt, M; Asiri, AM; Atac, A
    The spectroscopic (FT-IR, FT-Raman, H-1 and C-13 NMR, UV-Vis), structural, electronic and thermodynamical properties of 3-fluorophenylboronic acid (C6H4FB(OH)(2)), 3FPBA) were submitted by using both experimental techniques and theoretical methods (quantum chemical calculations) in this work. The experimental infrared and Raman spectra were obtained in the region 4000-400 cm(-1) and 3500-10 cm-1, respectively. The equilibrium geometry and vibrational spectra were calculated by using DFT (B3LYP) with 6-311++G(d,p) basis set. The vibrational wavenumbers were also corrected with scale factor to take better results for the calculated data. The total energy distributions (TED) of the vibrational modes were performed for the assignments of the title molecule by using scaled quantum mechanics (SQM) method. The NMR chemical shifts (H-1 and C-13) were recorded in DMSO solution. The H-1 and C-13 NMR spectra were computed by using the gauge-invariant atomic orbital (CIAO) method, showing a good agreement with the experimental ones. The last one UV-Vis absorption spectra were analyzed in two solvents (ethanol and water), saved in the range of 200-400 nm. In addition these, HOMO and LUMO energies, the excitation energies, density of states (DOS) diagrams, thermodynamical properties and molecular electrostatic potential surface (MEPs) were presented. Nonlinear optical (NLO) properties and thermodynamic features were performed. The experimental results are combined with the theoretical calculations using DFF calculations to fortification of the paper. At the end of this work, the results were proved our paper had been indispensable for the literature backing. (C) 2014 Elsevier B.V. All rights reserved.
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    FT-IR, FT-Raman, dispersive Raman, NMR spectroscopic studies and NBO analysis of 2-Bromo-1H-Benzimidazol by density functional method
    Sas, EB; Kurt, M; Karabacak, M; Poiyamozhi, A; Sundaraganesan, N
    In this study, geometrical optimization, FT-IR (4000-400 cm(-1)), FT-Raman (4000-40 cm(-1)), dispersive Raman (4000-40 cm-1) spectroscopic analysis, electronic structure and H-1 and C-13 nuclear magnetic resonance (NMR) studies of 2-Bromo-1H-Benzimidazol (abbreviated as 2Br1HB) were undertaken by utilizing DFT/B3LYP with 6-311+G(d,p) basis set. The results of the calculations were applied to simulate spectra of the title compound, which show good agreement with observed spectra. Complete vibrational assignments, analysis and correlations of the fundamental modes for 2Br1HB compound were carried out. Stability of the molecule arising from hyperconjugative interactions, charge delocalization was analyzed using natural bond orbital (NBO) analysis. The molecule orbital contributions were studied by using the total density of states (TDOS), partial density of states (PDOS), and overlap population density of states (OPDOS). The electronic properties like HOMO-LUMO energies and molecular electrostatic potential (MEP) analysis were reported. The calculated HOMO and LUMO energies shows that charge transfer interactions take place within the molecule. Mulliken population analysis on atomic charges was also calculated. Good correlation between the experimental H-1 and C-13 NMR chemical shifts in DMSO solution and calculated gauge-including atomic orbital (GIAO) shielding tensors were found. (C) 2014 Elsevier B.V. All rights reserved.
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    Synthesis and spectroscopic characterization on 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid: A DFT approach
    Kurt, M; Sas, EB; Can, M; Okur, S; Icli, S; Demic, S; Karabacak, M; Jayavarthanan, T; Sundaraganesan, N
    A complete structural and vibrational analysis of the 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid (TPBA), was carried out by ab initio calculations, at the density functional theory (DFT) method. Molecular geometry, vibrational wavenumbers and gauge including atomic orbital (CIAO) C-13 NMR and H-1 NMR chemical shift values of (TPBA), in the ground state have been calculated by using ab initio density functional theory (DFT/B3LYP) method with 6-311G(d,p) as basis set for the first time. Comparison of the observed fundamental vibrational modes of (TPBA) and calculated results by DFT/B3LYP method indicates that B3LYP level of theory giving yield good results for quantum chemical studies. Vibrational wavenumbers obtained by the DFT/B3LYP method are in good agreement with the experimental data. The study was complemented with a natural bond orbital (NBO) analysis, to evaluate the significance of hyperconjugative interactions and electrostatic effects on such molecular structure. By using TD-DFF method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFF method and the experimental one is determined. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals analysis and thermodynamic properties of TPBA were investigated using theoretical calculations. (C) 2015 Elsevier B.V. All rights reserved.