Cinar, Mehmet; Karabacak, Mehmet; Chand, Satish; Shukla, Vikas K.; Sinha, Leena; Prasad, Onkar; Singh, Manoj Pratap; Asiri, Abdullah M.

This study aims to identify the conformational and spectroscopic characteristics of 2,4-xylyl isothiocyanate (C9H9NS) compound via experimental and computational methods. To accomplish this, density functional theory (DFT), with the B3LYP functional was used to determine ground state conformation, vibrational wavenumbers and also isotropic chemical shifts of the title molecule. Experimentally, vibrational features of the compound were evaluated by FT-IR and FT-Raman spectroscopic analysis in the solid phase. On the basis of these studies, the conformational and spectroscopic behaviors of 2,4-xylyl isothiocyanate were interpreted. The fundamental vibrational wavenumbers as well as their intensities were computed, and a good correlation between experimental and scaled calculated wavenumbers was observed. The polarizability, first hyperpolarizability and dipole moment values of 2,4-xylyl isothiocyanate were calculated at the same level of theory and basis set. The results show that 2,4-xylyl isothiocyanate molecule possesses nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization was analyzed using natural bond orbital (NBO) analysis.

AtıfScopus7·WoS5·OpenAlex5

İncele

Cinar, Mehmet; Karabacak, Mehmet; Asiri, Abdullah 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.

AtıfScopus23·WoS22·OpenAlex24

İncele

Cinar, Mehmet; Coruh, Ali; Karabacak, Mehmet

In the present work, a combined experimental and quantum chemical study on ground state equilibrium structure, spectroscopic and nonlinear optical properties of selected disperse azo dye molecules are reported. The vibrational transitions were identified based on the recorded FT-IR spectra in the range of 4000-400 cm-1 for solid state, simulated IR spectra and total energy distribution (TED) of vibrational modes. The chemical shifts were determined from the results of observed 1H and 13C NMR spectra in chloroform and dimethylsulfoxide solution. The DFT/gauge-invariant atomic orbital (GIAO) methodology was applied to predict the magnetic properties. Electronic properties were carried out by UV-Vis spectroscopy and TD-DFT/CIS approach. The nonlinear optical (NLO) features were addressed theoretically. A detailed description of spectroscopic and NLO behaviors of studied disperse azo dyes was reported with the help of comparison of experimental measurements and theoretical calculations.

AtıfScopus30·WoS29·OpenAlex29

İncele

Karabacak, Mehmet; Sinha, Leena; Prasad, Onkar; Asiri, Abdullah M.; Cinar, Mehmet; Shukla, Vikas K.

Extensive spectroscopic investigations along with theoretical quantum chemical studies on 3,5-dimethyl-4-methoxybenzoic acid (DMMBA) have been consummated. The fundamental vibrational transitions were addressed by experimental FT-IR (4000-400 cm-1) and FT-Raman (4000-10 cm -1) techniques and density functional calculations at B3LYP/6-311++G(d,p) and B3LYP/6-311++G(df,pd) levels of theory. The 1H, 13C and DEPT 135 NMR spectra of studied compound were recorded in deuterated dimethylsulfoxide (DMSO-d6), and compared with computed data obtained by using gauge including atomic orbital (GIAO) method. The electronic absorption spectra in methanol and ethanol solution were evaluated in the range of 200-400 nm, and TD-DFT method was chosen for computational study. The spectroscopic and theoretical results were compared to the corresponding properties for monomer and dimer structures for the most stable conformer. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Moreover, the thermodynamic and nonlinear optical (NLO) properties were evaluated.

AtıfScopus34·WoS34

İncele

Cinar, Mehmet; Yildiz, Nihat; Karabacak, Mehmet; Kurt, Mustafa

The optimized geometrical structure, vibrational and electronic transitions, chemical shifts and nonlinear optical properties of 2-(4-hydroxyphenylazo)benzoic acid (HABA) compound were presented in this study. The ground state geometrical structure and vibrational wavenumbers were carried out by using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman spectrometry in the range of 4000-400 cm-1 and 4000-10 cm-1; respectively. The fundamental assignments were done on the basis of the recorded spectra and total energy distribution (TED) of the vibrational modes. The 1H and 13C NMR spectra were recorded in deuterated DMSO solution, and gauge-invariant atomic orbitals (GIAOs) method was used to predict the isotropic chemical shifts. The UV-Vis absorption spectra of the compound were observed in the range of 200-800 nm in ethanol, methanol and water solvents. To investigate the nonlinear optical properties, the polarizability, anisotropy of polarizability and molecular first hyperpolarizability were computed. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations.

AtıfScopus19·WoS19·OpenAlex19

İncele

Sinha, Leena; Karabacak, Mehmet; Narayan, V.; Cinar, Mehmet; Prasad, Onkar

Gabapentin (GP), structurally related to the neurotransmitter GABA (gamma-aminobutyric acid), mimics the activity of GABA and is also widely used in neurology for the treatment of peripheral neuropathic pain. It exists in zwitterionic form in solid state. The present communication deals with the quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of GP using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. In view of the fact that amino acids exist as zwitterions as well as in the neutral form depending on the environment (solvent, pH, etc.), molecular properties of both the zwitterionic and neutral form of GP have been analyzed. The fundamental vibrational wavenumbers as well as their intensities were calculated and compared with experimental FT-IR and FT-Raman spectra. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The electric dipole moment, polarizability and the first hyperpolarizability values of the GP have been calculated at the same level of theory and basis set. The nonlinear optical (NLO) behavior of zwitterionic and neutral form has been compared. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Ultraviolet-visible (UV-Vis) spectrum of the title molecule has also been calculated using TD-DFT method. The thermodynamic properties of both the zwitterionic and neutral form of GP at different temperatures have been calculated.

AtıfScopus53·WoS53·OpenAlex58

İncele

Cinar, Mehmet; Ozcan, Levent; Karabacak, Mehmet; Erol, Ibrahim

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.

AtıfScopus1·WoS1·OpenAlex1

İncele

Cinar, Mehmet; Karabacak, Mehmet

The optimized geometrical structure, vibrational and electronic transitions, chemical shifts and non-linear optical properties of ethyl trans-alfa-cyano-3-indole-acrylate (C14H12N 2O2) compound were presented in this study. The ground state geometrical structure and vibrational wavenumbers were carried out by using density functional (DFT/B3LYP) method with 6-311++G(d,p) as basis set. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman in the range of 4000-400 cm-1 and 4000-10 cm -1, respectively. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The 1H, 13C and DEPT NMR spectra were recorded in DMSO solution, and gauge-invariant atomic orbitals (GIAO) method was used to predict the isotropic chemical shifts. The UV-Vis absorption spectra of the compound were recorded in the range of 200-800 nm in various solvents of different polarity (acetone, benzene, chlorobenzene, chloroform, DMSO, ethanol, methanol and toluene). Solvent effects were calculated using TD-DFT and CIS method. To investigate the non-linear optical properties, the polarizability, anisotropy of polarizability and molecular first hyperpolarizability were computed. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations.

AtıfScopus12·WoS11

İncele

Karabacak, Mehmet; Sinha, Leena; Prasad, Onkar; Asiri, Abdullah M.; Cinar, Mehmet

The solid state Fourier transform infrared (FT-IR) and FT-Raman spectra of Acenaphthene-5-boronic acid (AN-5-BA), have been recorded in the range 4000-400 cm1 and 4000-10 cm 1, respectively. Density functional theory (DFT), with the B3LYP functional was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of the molecule. The vibrational wave numbers and their assignments were examined theoretically using the Gaussian 09 set of quantum chemistry codes and the normal modes were assigned by a scaled quantum mechanical (SQM) force field approach. Hydrogen-bonded dimer of AN-5-BA, optimized by counterpoise correction, has also been studied by B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H·O hydrogen bonding have been discussed. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge-Including Atomic Orbital (GIAO) method. Natural bond orbital (NBO) analysis has been applied to study stability of the molecule arising from charge delocalization. UV spectrum of the title compound was also recorded and the electronic properties, such as frontier orbitals, and band gap energies were measured by TD-DFT approach. The first order hyperpolarizability (β), its components and associated properties such as average polarizability and anisotropy of the polarizability (α and Δα) of AN-5-BA was calculated using the finite-field approach.

AtıfScopus38·WoS36·OpenAlex33

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