Halil Gökce

FT-IR, Micro-Raman and UV–vis spectroscopic and quantum chemical investigations of free 2,2′-dithiodipyridine and its metal (Co, Cu and Zn) halide complexes

In this study the elemental analysis results, molecular geometries, vibrational and electronic absorption spectra of free 2,2-dithiodipyridine(C10H8N2S2), (or DTDP) (with synonym, 2,2-dipyridyl disulfide) and M(C10H8N2S2)Cl2 (M=Co, Cu and Zn) complexes have been reported. Vibrational wavenumbers of free DTDP and its metal halide complexes have been calculated by using DFT/B3LYP calculation method with 6-31++G(d,p) and Lanl2DZ basis sets, respectively, in the ground state, for the first time. The calculated fundamental vibrational frequencies are in a good agreement with experimental data. The HOMO, LUMO and MEP analyses of all compounds are performed by DFT method.

Analysis of molecular structure, spectroscopic properties (FT-IR, micro-Raman and UV–vis) and quantum chemical calculations of free and ligand 2-thiopheneglyoxylic acid in metal halides (Cd, Co, Cu, Ni and Zn)

In this study, molecular geometries, experimental vibrational wavenumbers, electronic properties and quantum chemical calculations of 2-thiopheneglyoxylic acid molecule, (C6H4O3S), and its metal halides (Cd, Co, Cu, Ni and Zn) which are used as pharmacologic agents have been investigated experimentally by FT-IR, micro-Raman and UV-visible spectroscopies and elemental analysis. Meanwhile the vibrational calculations were verified by DFT/B3LYP method with 6-311++G(d,p) and LANL2DZ basis sets in the ground state, for free TPGA molecule and its metal halide complexes, respectively, for the first time. The calculated fundamental vibrational frequencies for the title compounds are in a good agreement with the experimental data.

DFT calculations, spectroscopy and antioxidant activity studies on (E)-2-nitro-4-[(phenylimino)methyl]phenol

We have reported synthesis and characterization of (E)-2-nitro-4-[(phenylimino)methyl]phenol by using X-ray crystallographic method, FT-IR and UV-vis spectroscopies and density functional theory (DFT). Optimized geometry and vibrational frequencies of the title compound in the ground state have been computed by using B3LYP with the 6-311G+(d,p) basis set. HOMO-LUMO energy gap, Non-linear optical properties and NBO analysis of the compound are performed at B3LYP/6-311G+(d,p) level. Additionally, as remarkable properties, antioxidant activity of the title compound (CMPD) has been determined by using different antioxidant test methods i.e. ferric reducing antioxidant power (FRAP), hydrogen peroxide scavenging (HPSA), free radical scavenging (FRSA) and ferrous ion chelating activities (FICA). When compared with standards (BHA, BHT, and α-tocopherol), we have concluded that CPMD has effective FRAP, HPSA, FRSA and FICA.

Spectroscopic and quantum chemical studies on bromopyrazone

In this study, the FT-IR, micro-Raman and UV-vis. spectra of bromopyrazone molecule, C10H8BrN3O, (with synonym,1-phenyl-4-amino-5-bromopyridazon-(6) or 5-amino-4-bromo-2-phenyl-3(2H)-pyridazinone) were recorded experimentally. The molecular structure, vibrational wavenumbers, electronic transition absorption wavelengths in ethanol solvent, HOMOs and LUMOs analyses, molecular electrostatic potential (MEP), natural bond orbitals (NBO), nonlinear optical (NLO) properties and atomic charges of bromopyrazone molecule have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set in ground state. The obtained results show that the calculated vibrational frequencies and UV-vis. values are in a good agreement with experimental data.

Isolation, characterization, spectroscopic properties and quantum chemical computations of an important phytoalexin resveratrol as antioxidant component from Vitis labrusca L. and their chemical compositions

In this study, isolation and characterization of trans-resveratrol (RES) as an antioxidant compound were carried out from VLE, VLG and VLS. Furthermore, antioxidant activities were evaluated by using six different methods. Finally, total phenolic, flavonoid, ascorbic acid, anthocyanin, lycopene, β-carotene and vitamin E contents were carried out. In addition, the FT-IR, (13)C and (1)H NMR chemical shifts and UV-vis. spectra of trans-resveratrol were experimentally recorded. Quantum chemical computations such as the molecular geometry, vibrational frequencies, UV-vis. spectroscopic parameters, HOMOs-LUMOs energies, molecular electrostatic potential (MEP), natural bond orbitals (NBO) and nonlinear optics (NLO) properties of title molecule have been calculated by using DFT/B3PW91 method with 6-311++G(d,p) basis set in ground state for the first time. The obtained results show that the calculated spectroscopic data are in a good agreement with experimental data.

The molecular structures, vibrational spectroscopies (FT-IR and Raman) and quantum chemical calculations of n-alkyltrimethylammonium bromides

The FT-IR and micro-Raman spectra of three n-alkyltrimethylammonium bromides (dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB) and hexadecyl(cetyl)trimethylammonium bromide (CTAB)) in powder form were recorded in the regions 4000–550 cm−1 and 3200–300 cm−1, respectively. The optimized geometries and vibrational frequencies of DTAB, TTAB and CTAB have been carried out with ab initio Hartree-Fock (HF) and density functional theory method B3LYP calculations with the 6–31 G (d, p) basis set in the ground state. The comparison of the observed fundamental vibrational frequencies and calculated results for the fundamental vibrational frequencies of DTAB, TTAB and CTAB indicate that the scaled B3LYP method is superior compared to the scaled HF method.

Thiol–thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV–vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule

In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data.

Spectroscopic characterization and quantum chemical computations of the 5-(4-pyridyl)-1H-1,2,4-triazole-3-thiol molecule

ABSTRACT The Fourier transform infrared, laser-Raman, proton and carbon-13 nuclear magnetic resonance chemical shifts, and Ultraviolet (UV)-Visible spectra of the 5-(4-pyridyl)-1H-1,2,4-triazole-3-thiol molecule have been experimentally recorded. The molecular geometric structure analysis, vibrational frequencies, electronic absorption spectroscopy, frontier molecular orbital energies, and molecular electrostatic potential of the 5-(4-pyridyl)-1H-1,2,4-triazole-3-thiol molecule have been calculated by using density functional theory calculations with the 6-311++G(d,p) basis set in the ground state, for the first time. Additionally, natural bond orbitals and non-linear optical properties of the 5-(4-pyridyl)-1H-1,2,4-triazole-3-thiol molecule have been theoretically investigated by using the mentioned level. The obtained results show that the theoretical values are in good agreement with experimental data.

Crystallographic structure and quantum chemical computations of 1-(3,4-dimethylphenyl)-3-phenyl-5-(4-methoxyphenyl)-2-pyrazoline.

In this study the experimental crystallographic structure and the calculated optimized geometric parameters, vibrational wavenumbers, (1)H NMR and (13)C NMR chemical shift values, electronic absorption maximum wavelength values, HOMO-LUMO analysis, and molecular electrostatic potential (MEP) of 1-(3,4-dimethylphenyl)-3-phenyl-5-(4-methoxyphenyl)-2-pyrazoline (in abbreviated 1h), molecule, (C24H24N2O), by using density functional theory (DFT/B3LYP) method with 6-311++G(d,p) basis set in the ground state have been reported for the first time. Furthermore the IR and Raman spectra of title molecule were simulated by using calculated vibrational results. Geometric parameters (bond lengths and bond angles) vibrational wavenumbers and (13)C &(1)H NMR chemical shift values for the mentioned compound calculated at B3LYP/6-311++G(d,p) level are in good agreement with the experimental data.

Spectroscopic (vibrational, NMR and UV-vis.) and quantum chemical investigations on 4-hexyloxy-3-methoxybenzaldehyde.

In this study, the 4-hexyloxy-3-methoxybenzaldehyde compound as one of the derivatives of vanillin which is a well known flavoring agent, C14H20O3, has been investigated by experimentally and extensively utilizing density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. In this context, the optimized geometry, vibrational frequencies, (1)H and (13)C NMR chemical shifts, UV-vis. (in gas phase and in methanol solvent) spectra, HOMO-LUMO analysis, molecular electrostatic potential (MEP), thermodynamic parameters and atomic charges of 4-hexyloxy-3-methoxybenzaldehyde have been calculated. In addition, theoretically predicted IR, Raman and UV-vis. (in gas phase and in methanol solvent) spectra of the mentioned molecule have been constructed. The results calculated were compared with the experimental data.