Synthesis, characterization, and quantum chemical calculational studies on 3-p-methylphenyl-4-amino- 1, 2, 4-triazole-5-thione

Molecular structure, vibrational spectra, natural bond orbital and thermodynamic analysis of 3,6-dichloro-4-methylpyridazine and 3,6-dichloropyridazine-4-carboxylic acid by dft approach

Vibrational spectral analysis of the molecules 3,6-dichloro-4-methylpyridazine (DMP) and 3,6-dichloropyridazine-4-carboxylic acid (DPC) was carried out using FT-IR and FT-Raman spectroscopic techniques. The molecular structure and vibrational spectra of DMP and DPC were obtained by the density functional theory (DFT) method, using B3LYP functional, with 6-311++G(d,p) basis set. A detailed interpretation of the Infrared and Raman spectra of the two molecules were reported based on potential energy distribution (PED). The theoretically predicted FTIR and FT-Raman spectra of the titled molecules have been simulated and were compared with the experimental spectra. Determination of electric dipole moment (μ) and hyperpolarizability β0 helps to study the non-linear optical (NLO) behavior of DMP and DPC. Stability of the molecules arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. (13)C and (1)H NMR spectra were recorded and (13)C and (1)H NMR chemical shifts of the molecules were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compounds was also recorded in the region 200-1100 nm and electronic properties, HOMO (Highest Occupied Molecular Orbitals) and LUMO (Lowest Unoccupied Molecular Orbitals) energies were measured by time-dependent TD-DFT approach. Charge density distribution and site of chemical reactivity of the molecule have been studied by mapping electron density isosurface with molecular electrostatic potential (MESP).

Structural, vibrational, electronic and NMR spectral analysis of 3-chloro-6-methoxypyridazine by DFT calculations

In this work, the FT-Raman and FT-Infrared spectra of 3-chloro-6-methoxypyridazine sample were measured to elucidate the spectroscopic properties of title molecule in the spectral range of 3500-50 cm(-1) and 4000-400 cm(-1), respectively. The molecular geometry and vibrational frequencies of 3-chloro-6-methoxypyridazine in the ground state were calculated using the DFT/B3LYP/6-31G(d),6-311G(d,p) level. The recorded FT-IR and FT-Raman spectral measurements favor the calculated structural parameters which are further supported by spectral simulation. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The UV-Visible absorption spectrum of the compound that dissolved in methanol was recorded in the range of 800-200 nm. The formation of hydrogen bond and the most possible interaction are explained using natural bond orbital (NBO) analysis. The isotropic chemical shift computed by (13)C and (1)H NMR analysis also shows good agreement with experimental observations. In addition, the molecular electrostatic potential (MEP) and frontier molecular orbitals (FMOs) analysis of the title compound were investigated using theoretical calculations.

Synthesis, structural characterization and comparison of experimental and theoretical results by DFT level of molecular structure of 4-(4-methoxyphenethyl)-3,5-dimethyl-4H-1,2,4-triazole

4-(4-Methoxyphenethyl)-3,5-dimethyl-4H-1,2,4-triazole (3) was synthesized from the reaction of ethyl N'-acetylacetohydrazonate (1) with 2-(4-methoxyphenyl)ethanamine (2). The structure of the title compound 3 has been inferred through IR, (1)H/(13)C NMR, mass spectrometry, elemental analyses and combination of X-ray crystallography and theoretical methods. In addition to the molecular geometry from X-ray determination, the molecular geometry and vibrational frequencies of the title compound 3 in the ground state, were 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 show good agreement with experimental values. The nonlinear optical properties are also addressed theoretically. The predicted nonlinear optical properties of 3 are greater than ones of urea. In addition, DFT calculations of molecular electrostatic potentials and frontier molecular orbitals of the title compound were carried out at the B3LYP/6-31G(d) level of theory.

4-Allyl-5-pyridin-4-yl-2,4-dihydro-3H-1,2,4-triazole-3-thione: synthesis, experimental and theoretical characterization

The title molecule, 4-allyl-5-pyridin-4-yl-2,4-dihydro-3H-1,2,4-triazole-3-thione (C(10)H(10)N(4)S), was synthesized and characterized by IR-NMR spectroscopy and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group is P2(1)/c, a=8.006(5)Å, b=15.363(5)Å, c=8.936(5)Å, β=104.441(5)° and V=1064.4(10)Å(3), F(000)=456, D(x)=1.362 g/cm(3). In addition to the molecular geometry from X-ray experiment, the molecular geometry, vibrational frequencies, gauge including atomic orbital (GIAO) (1)H and (13)C chemical shift values of the title compound in the ground state have been calculated using the Hartree-Fock (HF) and density functional method (DFT/B3LYP) with 6-31G(d) basis set. To determine conformational flexibility, molecular energy profile of the title compound was obtained by HF/6-31G(d) and (DFT/B3LYP) calculations with respect to selected degree of torsional freedom, which was varied from -180° to +180° in steps of 10°. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO), and several thermodynamic properties were performed by the HF and DFT methods.

Molecular structure and vibrational bands and chemical shift assignments of 4-allyl-5-(2-hydroxyphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione by DFT and ab initio HF calculations

The title molecule, 4-allyl-5-(2-hydroxyphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (C(11)H(11)N(3)OS), was synthesized and characterized by IR-NMR spectroscopy and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group is P2(1)/c, a=9.0907(5)A, b=9.1288(7)A, c=13.6222(7)A, alpha=90 degrees , beta=98.442 (4), gamma=90 degrees and V=2683.7(6)A(3), F(000)=488, D(x)=1.386 g/cm(3). In addition to the molecular geometry from X-ray experiment, the molecular geometry, vibrational frequencies, gauge including atomic orbital (GIAO) (1)H and (13)C chemical shift values of the title compound in the ground state have been calculated using the Hartree-Fock (HF) and density functional method (DFT/BLYP and DFT/B3LYP) with 6-31G(d) basis set. To determine conformational flexibility, molecular energy profile of the title compound was obtained by HF/6-31G(d) calculations with respect to selected degree of torsional freedom, which was varied from -180 degrees to +180 degrees in steps of 10 degrees . Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO), and several thermodynamic properties were performed by the HF and DFT methods.