Browsing by Subject "Spectroscopic characterization"
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Item Synthesis, spectroscopic characterization and quantum chemical computational studies of (S)-N-benzyl-1-phenyl-5-(pyridin-2-yl)-pent-4-yn-2- amine(2012) Kose E.; Atac A.; Karabacak M.; Karaca C.; Eskici M.; Karanfil A.The synthesis and characterization of a novel compound (S)-N-benzyl-1- phenyl-5-(pyridin-2-yl)-pent-4-yn-2-amine (abbreviated as BPPPYA) was presented in this study. The spectroscopic properties of the compound were investigated by FT-IR, NMR and UV spectroscopy experimentally and theoretically. The molecular geometry and vibrational frequencies of the BPPPYA in the ground state were calculated by using density functional theory (DFT) B3LYP method invoking 6-311++G(d,p) basis set. The geometry of the BPPPYA was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The results of the energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) and CIS approach complement with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis were presented. The theoretical NMR chemical shifts (1H and 13C) complement with experimentally measured ones. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. The calculated vibrational wavenumbers, absorption wavelengths and chemical shifts showed the best agreement with the experimental results. © 2012 Elsevier B.V. All rights reserved.Item Absorption and photoluminescence spectroscopy of Er 3+-doped SrAl 2O 4 ceramic phosphors(2012) Ayvackl M.; Khatab A.; Ege A.; Şabikoǧlu I.; Henini M.; Can N.A spectroscopic characterization of Er 3+-doped SrAl 2O 4 phosphor materials synthesized by a solid-state reaction method with Er concentrations varying from 0.1 to 1 mol% has been performed by studying photoluminescence (PL) in the temperature range 10 to 360K and absorption spectra. PL signals containing five emission bands at 1492, 1529, 1541, 1558, and 1600nm, respectively, have been observed at room temperature for Er 3+ transitions in the near infrared region. The samples exhibit a main luminescence peak at 1.54 μm, which is assigned to recombination via an intra-4f Er 3+ transition. Sharp bands centered at around 378, 488, 521, 651, 980, 1492, and 1538nm in the absorption spectra can be associated with transitions from 4I 15/2 level to 2H 9/2, 4F 7/2, 2H 11/2, 4F 9/2, 4I 11/2, 2H 11/2, and 4I 13/2 levels, respectively. The sharp emission peaks and excellent luminescence properties show that SrAl 2O 4 is a suitable host for rare-earth-doped phosphors, which may be suitable for optical applications. © 2012 Taylor & Francis.Item Molecular structure, spectroscopic characterization (FT-IR, FT-Raman, UV and NMR), HOMO and LUMO analysis of 3-ethynylthiophene with DFT quantum chemical calculations(Elsevier B.V., 2013) 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 cm1 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 1H, 13C and HMQC (1H- 13C 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. © 2013 Elsevier B.V. All rights reserved.Item Synthesis, conformational and spectroscopic characterization of monomeric styrene derivatives having pendant p-substituted benzylic ether groups(2013) Cinar M.; Ozcan L.; Karabacak M.; Erol I.Three derivatives of styrene monomer, 4-chlorophenyl-4-vinylbenzyl ether (I), 4-methoxyphenyl-4-vinylbenzyl ether (II) and 4-ethylphenyl-4-vinylbenzyl ether (III) were synthesized. The synthesized two novel compounds (I and III) and one with undefined structural features were identified by experimental spectroscopic techniques and density functional approach. The optimized geometrical structure, vibrational and electronic transitions along with chemical shifts of those compounds were presented in this study. The vibrational spectra of investigated compounds were recorded in solid state with FT-IR spectrometry in the range of 4000-400 cm-1. The computational vibrational wavenumbers and also ground state equilibrium conformations were carried out by using density functional method with 6-311++G(d,p) basis set. Assignments of the fundamental vibrational modes were examined on the basis of the measured data and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. Isotropic chemical shift of hydrogen and carbon nuclei were investigated via observed 1H and 13C NMR spectra in deuterated DMSO solution and predicted data applied with gauge-invariant atomic orbitals (GIAOs) method. The UV absorption spectra of monomers were observed in the range of 200-800 nm in ethanol, and time dependent DFT method was used to obtain the electronic properties. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations. © 2013 Elsevier B.V. All rights reserved.Item An experimental and density functional study on conformational and spectroscopic analysis of 5-methoxyindole-2-carboxylic acid(Elsevier B.V., 2015) Cinar M.; Karabacak M.; Asiri A.M.In this article, a brief conformational and spectroscopic characterization of 5-methoxyindole-2-carboxylic acid (5-MeOICA) via experimental techniques and applications of quantum chemical methods is presented. The conformational analysis of the studied molecule was determined theoretically using density functional computations for ground state, and compared with previously reported experimental findings. The vibrational transitions were examined by measured FT-IR and FT-Raman spectroscopic data, and also results obtained from B3LYP and CAM-B3LYP functionals in combination with 6-311++G(d,p) basis set. The recorded proton and carbon NMR spectra in DMSO solution were analyzed to obtain the exact conformation. Due to intermolecular hydrogen bondings, NMR calculations were performed for the dimeric form of 5-MeOICA and so chemical shifts of those protons were predicted more accurately. Finally, electronic properties of steady compound were identified by a comparative study of UV absorption spectra in ethanol and water solution and TD-DFT calculations. © 2014 Elsevier B.V. All rights reserved.Item Molecular structure, spectroscopic characterization, HOMO and LUMO analysis of 3,3′-diaminobenzidine with DFT quantum chemical calculations(Elsevier, 2015) Karabacak M.; Bilgili S.; Atac A.In this work, infrared, Raman and UV spectra of 3,3′-diaminobenzidine (3,3-DAB) were carried out by using density functional theory (DFT)/B3LYP method with 6-311G(d,p) basis set. FT-IR and FT-Raman spectra were recorded in the region 4000-400 and 4000-50 cm-1, respectively. The geometrical parameters, energies and wavenumbers were obtained and fundamental vibrations were assigned on the basis of the potential energy distribution (PED) of the vibrational modes. The UV spectrum of the investigated compound was recorded in the range of 200-400 nm in ethanol and water solutions. 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. Thermodynamic properties, Mulliken atomic charges and molecular electrostatic potential (MEP) were calculated for the title molecule. Also the nonlinear optical properties of 3,3-DAB molecule were explored theoretically. As a result, the calculated results were compared with the observed values and generally found to be in good agreement. © 2015 Elsevier B.V. All rights reserved.Item Spectroscopy, thermoluminescence and afterglow studies of CaLa4(SiO4)3O:Ln (Ln=Ce, Nd, Eu, Tb, Dy)(Elsevier B.V., 2015) Dobrowolska A.; Karsu E.C.; Bos A.J.J.; Dorenbos P.The spectroscopic characterization down to 10 K was performed for undoped and Ln doped CaLa4(SiO4)3O (Ln=Eu3+, Eu2+, Ce3+, Dy3+, Tb3+). Based on the experimental and literature data the scheme was constructed showing the vacuum referred binding energy (VRBE) of electrons in lanthanide states and band states in CaLa4(SiO4)3O. This scheme predicts that co-doping with Eu2+ and Ln3+ (Ln=Dy, Nd) will induce afterglow. Thermoluminescence and afterglow were indeed measured and compared with a commercial SrAl2O4:Eu, Dy afterglow phosphor. © 2015 Elsevier B.V. All rights reserved.Item Synthesis, single crystal structure, spectroscopic characterization and molecular properties of (2E)-3-(2,6-dichlorophenyl)-1-(3,4-dimethoxyphenyl)prop-2-en-1-one(Elsevier B.V., 2016) Chidan Kumar C.S.; Quah C.K.; Balachandran V.; Fun H.-K.; Asiri A.M.; Chandraju S.; Karabacak M.A novel (2E)-3-(2,6-dichlorophenyl)-1-(3,4-dimethoxyphenyl)prop-2-en-1-one (DCPDMP) compound has been synthesized and its single crystal has been grown by slow evaporation technique. The structure of the compound has been characterized by FT-IR, FT-Raman and single-crystal X-ray diffraction techniques. The optimized molecular structure, vibrational wavenumbers, corresponding vibrational assignments of the compound have been investigated by means of the density functional theory. The molecule crystallizes in triclinic system, space group P-1 with a = 7.6179 (7), b = 8.5023 (7), c = 12.1967 (10) Å, V = 764.39 (11) Å3 and two molecules in the unit cell. The crystal structure is primarily stabilized through intramolecular C–H … Cl and C–H … O hydrogen bonds and intermolecular C–H … O and weak C–H … π interactions. These inter- and intramolecular interactions are analyzed. Moreover, the molecular electrostatic potential surface of the molecule has been constructed. Global and local reactivity descriptors and dipole moment (μ), static polarizability (α), first order hyperpolarizability (β) and optical gap (ΔE) have been also calculated to study the nonlinear optical (NLO) property of the title compound. © 2016 Elsevier B.V.Item Conformational, electronic, and spectroscopic characterization of isophthalic acid (monomer and dimer structures) experimentally and by DFT(Elsevier B.V., 2016) Bardak F.; Karaca C.; Bilgili S.; Atac A.; Mavis T.; Asiri A.M.; 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, 1H and 13C 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 (1H and 13C) 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 13C and 1H 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. © 2016 Elsevier B.V. All rights reserved.Item Luminescent properties of scintillator nanophosphors produced by flame spray pyrolysis(Elsevier B.V., 2017) Yildirim S.; Karsu Asal E.C.; Ertekin K.; Celik E.In the present work flame spray pyrolysis synthesis and characterization of the nano-scale phosphors; M′-YTaO4 and M′-Y(Ta0.85Nb0.15)O4 have been studied for the first time. Phase and elemental analysis of the produced nanophosphors were carried out by X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS) measurements, respectively. The surface morphology and particle size of the nanophosphors were identified using scanning electron microscopy (SEM). The XRD results reveal that the nanophosphors have monoclinic M′-YTaO4 and M′-Y(Ta0.85Nb0.15)O4 phases belonging to the presence of M´-form of fergusonite structure. The particle sizes of the nanophosphors were found to be in the range of 50–100 nm. The spectroscopic characterization was performed by both radioluminescence (RL) and thermally stimulated luminescence (TSL) measurements after exposure to X-ray irradiation. Also, photoluminescence and decay times were investigated under UV excitation. The nanophosphors can be concluded as appropriate emissive materials for imaging, display and scintillator applications due to the efficient photoluminescence, moderate radioluminescence (RL) and thermally stimulated luminescence characteristics. © 2017 Elsevier B.V.