Browsing by Author "Mavis, T"

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    Conformational, electronic, and spectroscopic characterization of isophthalic acid (monomer and dimer structures) experimentally and by DFT
    Bardak, F; Karaca, C; Bilgili, S; Atac, A; Mavis, T; Asiri, AM; Karabacak, M; Kose, E
    Isophthalic acid (C6H4(CO2H)(2)) is a noteworthy organic compound widely used in coating and synthesis of resins and the production of commercially important polymers such as drink plastic bottles. The effects of isophthalic acid (IPA) on human health, toxicology, and biodegradability are the main focus of many researchers. Because structural and spectroscopic investigation of molecules provides a deep understanding of interactional behaviors of compounds, this study stands for exploring those features. Therefore, the spectroscopic, structural, electronic, and thermodynamical properties of IPA were thoroughly studied in this work experimentally using UV-Vis, H-1 and C-13 NMR, FT-IR, FT-Raman and theoretically via DFT and TD-DFT calculations. The UV-Vis absorption spectrum in water was taken in the region 200-400 nm. The NMR chemical shifts CH and C-13) were recorded in DMSO solution. The infrared and Raman spectra of the solid IPA were recorded in the range of 4000-400 cm(-1) and 3500-50 cm(-1), respectively. DFT and TD-DFT calculations were performed at the level of B3LYP/6-311 ++G(d,p) in determination of geometrical structure, electronic structure analysis and normal mode. The C-13 and H-1 nuclear magnetic resonance (NMR) spectra were estimated by using the gauge-invariant atomic orbital (GIAO) method. The scaled quantum mechanics (SQM) method was used to determine the total energy distribution (TED) to assign the vibrational modes accurately. Weak interactions such as hydrogen bonding and Van der Walls were analyzed via reduced density gradient (RDG) analysis in monomeric and dimeric forms. Furthermore, the excitation energies, density of state (DOS) diagram, thermodynamical properties, molecular electro-static potential (MEP), and nonlinear optical (NLO) properties were obtained. (C) 2016 Elsevier B.V. All rights reserved.
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    Molecular structure, spectroscopic characterization (FT-IR, FT-Raman, UV and NMR), HOMO and LUMO analysis of 3-ethynylthiophene with DFT quantum chemical calculations
    Karabacak, M; Bilgili, S; Mavis, T; Eskici, M; Atac, A
    In this work, FT-IR, FT-Raman, UV and NMR spectra of 3-ethynylthiophene (3-ETP, C6H4S) were carried out by using density functional theory DFT/B3LYP method with the 6-311++G(d,p), 6-311+G(d,p), 6-311G(d,p), 6-31++G(d,p), 6-31+G(d,p), 6-31G(d,p) basis sets. FT-IR and FT-Raman spectra were recorded in the regions of 3500-400 cm(-1) and 3500-50 cm(-1), respectively. The geometrical parameters, energies and wavenumbers were obtained and the complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The H-1, C-13 and HMQC (H-1-C-13 correlation) NMR spectra in chloroform (CDCl3) were recorded and calculated. The UV spectrum of investigated compound were recorded in the region of 200-400 nm in ethanol solution. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies were performed by DFT/B3LYP approach and the results were compared with experimental observations. The thermodynamic properties such zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment of the studied compound were calculated. As a result, the calculated results were compared with the observed data and found to be in good agreement. (C) 2013 Elsevier B.V. All rights reserved.