DFT computational modeling studies on 4-(2,3-Dihydroxybenzylideneamino)-3-methyl-1H-1,2,4-triazol-5(4H)-one

Molecular structure and vibrational and chemical shift assignments of 3'-chloro-4-dimethylamino azobenzene by DFT calculations

In the present work, a combined experimental and theoretical study on ground state molecular structure, spectroscopic and nonlinear optical properties of azo compound 3'-chloro-4-dimethlamino azobenzene are reported. The molecular geometry, vibrational wavenumbers and the first order hyperpolarizability of the title compound were calculated with the help of density functional theory computations. The optimized geometric parameters obtained by using DFT (B3LYP/6-311++G(d,p)) show good agreement with the experimental data. The vibrational transitions were identified based on the recorded FT-IR spectra in the range of 4000-400cm(-1) for solid state. The (1)H isotropic chemical shifts with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. Using the TD-DFT method, electronic absorption spectra of the title compound have been predicted, and good agreement is determined with the experimental ones. To investigate the NLO properties of the title compound, the polarizability and the first hyperpolarizability were calculated using the density functional B3LYP method with the 6-311++G(d,p) basis set. According to results, the title compound exhibits non-zero first hyperpolarizability value revealing second order NLO behavior. In addition, DFT calculations of the title compound, molecular electrostatic potential and frontier molecular orbitals were also performed at 6-311++G(d,p) level of theory.

Crystal structure, spectroscopic studies and quantum mechanical calculations of 2-[((3-iodo-4-methyl)phenylimino)methyl]-5-nitrothiophene

The title compound, 2-[((3-iodo-4-methyl)phenylimino)methyl]-5-nitrothiophene, C12H9O2N2I1S1, was synthesized and characterized by IR, UV-Vis and single-crystal X-ray diffraction technique. The molecular structure was optimized at the B3LYP, B3PW91 and PBEPBE levels of the density functional method (DFT) with the 6-311G+(d,p) basis set. Using the TD-DFT method, the electronic absorption spectra of the title compound was computed in both the gas phase and ethanol solvent. The harmonic vibrational frequencies of the title compound were calculated using the same methods with the 6-311G+(d,p) basis set. The calculated results were compared with the experimental determination results of the compound. The energetic behavior such as the total energy, atomic charges, dipole moment of the title compound in solvent media were examined using the B3LYP, B3PW91 and PBEPBE methods with the 6-311G+(d,p) basis set by applying the Onsager and the polarizable continuum model (PCM). The molecular orbitals (FMOs) analysis, the molecular electrostatic potential map (MEP) and the nonlinear optical properties (NLO) for the title compound were obtained with the same levels of theory. And then thermodynamic properties for the title compound were obtained using the same methods with the 6-311G(d,p) basis set.

Experimental and theoretical studies of (E)-2-(2-hydroxystyryl)-6-(4-methoxybenzoyl)-5-(4-methoxyphenyl)-1,2,4-triazin-3(2H)-one

Crystal structure of the title compound, C26H21N3O5, has been synthesized and characterized by FT-IR, (1)H NMR, (13)C NMR and X-ray single crystal determination. The molecular geometry was also calculated by using Gaussian 03 software and structure was optimized by using HF and DFT/B3LYP method with the 6-31G(d) basis sets in ground state. The comparison of the theoretical and experimental geometries of the title compound indicated that the X-ray parameters agree with the theoretically obtained values. It was seen that R(2) value changes from 0.015 to 0.021 Å for bond length and angle. The calculated vibrational frequencies are also in good agreement with the experimental results. The (1)H and (13)C NMR chemical shifts values of (E)-2-(2-hydroxystyryl)-6-(4-methoxybenzoyl)-5-(4-methoxyphenyl)-1,2,4-triazin-3(2H)-one molecule have been calculated by the GIAO method. Besides, molecular electrostatic potential maps (MEP), Mulliken charges and Nonlinear Optical effects (NLO) analysis of the compound have been calculated by the HF and B3LYP/6-31G(d) methods.

Structural, vibrational and electronic characterization of 1-benzyl-3-furoyl-1-phenylthiourea: an experimental and theoretical study

The compound 1-benzyl-3-furoyl-1-phenylthiourea was synthesized and characterized through IR and Raman spectroscopy and its molecular structure was determined.

Structural, vibrational and theoretical studies of anilinium trichloroacetate: new hydrogen bonded molecular crystal with nonlinear optical properties

In this work, we report a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of the potential nonlinear optical (NLO) material anilinium trichloroacetate. The FT-IR and FT-Raman spectra of the compound have been recorded together between 4000-80 cm(-1) and 3600-80 cm(-1) regions, respectively. The compound crystallizes in the noncentrosymmetric space group of monoclinic system. The optimized molecular structure, vibrational wavenumbers, IR intensities and Raman activities have been calculated by using density functional method (B3LYP) with 6-311++G(d,p) as higher basis set. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. DSC measurements on powder samples do not indicate clearly on the occurrence of phase transitions in the temperature 113-293 K. The Kurtz and Perry powder reflection technique appeared to be very effective in studies of second-order nonlinear optical properties of the molecule. The non-linear optical properties are also addressed theoretically. The predicted NLO properties of the title compound are much greater than ones of urea. In addition, DFT calculations of the title compound, molecular electrostatic potential, frontier orbitals and thermodynamic properties were also performed at 6-311++G(d,p) level of theory. For title crystal the SHG efficiency was estimated by Kurtz-Perry method to be d(eff)=0.70 d(eff) (KDP).

Crystal structure, spectroscopic characterization and density functional studies of (E)-1-((3-methoxyphenylimino)methyl)naphthalen-2-ol

The Schiff base compound (E)-1-((3-methoxyphenylimino)methyl)naphthalen-2-ol was synthesized from the reaction of 2-hydroxy-1-naphthaldehyde with 3-methoxyaniline. The structural properties of the compound has been characterized by using FT-IR, UV-vis and X-ray single-crystal methods. According to X-ray diffraction result, the title compound exists in the phenol-imine tautomeric form. The molecular geometry, vibrational frequencies of the compound in the ground state have been calculated using the density functional theory (DFT/B3LYP) method with the 6-311++G(d,p) basis set, and compared with the experimental data. The obtained results show that the optimized molecular geometry is well reproduce the crystal structure. The theoretical vibrational frequencies are in good agreement with the experimental values. The calculations of electronic absorption spectra of tautomeric forms of the compound were performed by using TD-DFT calculations both in the gas phase and ethanol solvent. To investigate the tautomeric stability, optimization calculations at the B3LYP/6-311++G(d,p) level were performed for the phenol-imine and keto-amine forms of the compound. According to calculated results, the OH form is more stable than NH form. In addition, molecular electrostatic potential (MEP), frontier molecular orbital analysis (HOMO-LUMO), thermodynamic and, non-linear optical (NLO) properties of the compound were investigated using same theoretical calculations.

Synthesis, experimental, theoretical characterization and biological activities of 4-ethyl-5-(2-hydroxyphenyl)-2H-1,2,4-triazole-3(4H)-thione

This work presents the characterization of 4-ethyl-5-(2-hydroxyphenyl)-2H-1,2,4-triazole-3(4H)-thione (III) by quantum chemical calculations and spectral techniques. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) (1)H and (13)C NMR chemical shift values of III in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. To determine conformational flexibility, the molecular energy profile of the title compound was obtained by DFT calculations with respect to the selected torsion angle, which was varied from -180° to +180° in steps of 10°. The energetic behavior of III in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). The predicted nonlinear optical properties of III are greater than ones of urea. In addition, DFT calculations of molecular electrostatic potentials and frontier molecular orbitals of III were carried out at the B3LYP/6-31G(d) level of theory. The title compound was screened for antibacterial, antifungal and antioxidant activities.

FT-IR, FT-Raman spectra, NBO, HOMO-LUMO and thermodynamic functions of 4-chloro-3-nitrobenzaldehyde based on ab initio HF and DFT calculations

FT-IR (4000-400 cm(-1)) and FT-Raman (3500-100 cm(-1)) spectral measurements of 4-chloro-3-nitrobenzaldehyde have been done. Ab initio (HF/6-311+G(d,p)) and DFT (B3LYP/6-311+G(d,p)) calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies, infrared intensities and Raman activities. A detailed interpretation of the FT-IR and FT-Raman spectra of 4-chloro-3-nitrobenzaldehyde are reported on the basis of the calculated potential energy distribution. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The HOMO and LUMO energy gap reveals that the energy gap reflects the chemical activity of the molecule. The thermodynamic functions of the title compound have been performed by HF/6-311+G(d,p) and B3LYP/6-311+G(d,p). The observed and calculated wave numbers are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed spectra. Thermodynamic functions were calculated using vibrational wave numbers for different temperatures.

N-cyclohexyl-2-[5-(4-pyridyl)-4-(p-tolyl)-4H-1,2,4-triazol-3-ylsulfanyl]-acetamide dihydrate: synthesis, experimental, theoretical characterization and biological activities

The triazol compound N-cyclohexyl-2-[5-(4-pyridyl)-4-(p-tolyl)-4H-1,2,4-triazol-3-ylsulfanyl]-acetamide dihydrate has been synthesized and characterized by (1)H NMR, (13)C NMR, IR, and X-ray single-crystal determination. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) (1)H and (13)C NMR chemical shift values of III in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. The energetic behavior of III in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). The predicted nonlinear optical properties of III are greater than ones of urea. In addition, DFT calculations of molecular electrostatic potentials, frontier molecular orbitals and thermodynamic properties of III were carried out at the B3LYP/6-31G(d) level of theory. The title compound was screened for antibacterial, antifungal and antioxidant activities.

DFT QUANTUM CHEMICAL STUDIES ON 1-[N-(2-PYRİDYL) AMİNOMETHYLİDENE]-2(1H)-NAPHTALENONE

Quantum chemical calculations of the structure, molecular electrostatic potential and thermodynamic functions have been performed using the density functional (DFT/B3LYP) method with the 6-311++G(d,p) basis set for the title compound 1-[N-(2-pyridyl)aminomethylidene}-2(1H)-Naphtalenone. The energetic behavior of the title compound in solvent media has been examined by applying the Onsager and the polarizable continuum model. To investigate second order nonlinear optical properties of the title compound, the electric dipole μ, the polarizability α and the first hyperpolarizability β were computed using the density functional B3LYP and CAM-B3LYP methods with the 6-311++G(d,p) basis set. According to our calculations, the title compound exhibits nonzero β value revealing second order NLO behavior. The changes of thermodynamic properties for the formation of the title compound with the temperature ranging from 200 K to 500 K have been obtained using the statistical thermodynamic method. The relationship between formation enthalpy and entropy changes has been investigated with the entropy–enthalpy compensation. Besides, natural bond orbital and frontier molecular orbital analysis of the title compound were investigated by theoretical calculations.

Crystal structure, spectroscopic investigations and density functional studies of 4-(4-methoxyphenethyl)-5-benzyl-2H-1,2,4-triazol-3(4H)-one monohydrate

The triazol compound 4-(4-methoxyphenethyl)-5-benzyl-2H-1,2,4-triazol-3(4H)-one monohydrate (I) has been synthesized and characterized by (1)H NMR, (13)C NMR, IR, and X-ray single-crystal determination. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) (1)H and (13)C NMR chemical shift values of (I) in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. The energetic behavior of (I) in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). The predicted non-linear optical properties of (I) are greater than ones of urea. In addition, DFT calculations of molecular electrostatic potentials, frontier molecular orbitals and thermodynamic properties of (I) were carried out at the B3LYP/6-31G(d) level of theory.