title: HOMO-LUMO, UV, NLO, NMR and vibrational analysis of 3-methyl-1-phenylpyrazole using FT-IR, FT-RAMAN FT-NMR spectra and HF-DFT computational methods.
abstract: In this paper, the spectral analysis of 3-methyl-1-phenylpyrazole is carried out using the FT-IR, FT Raman, FT NMR and UV-Vis spectra with the help of quantum mechanical computations using HF and density functional theories. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G (d,p) basis set and the most stable conformer with minimum energy was identified and the same conformer was used for further computations. The computed wave numbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both HF and B3LYP methods with 6-311+G (d,p) and 6-311++G (d,p) basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non-linear property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for (1)H and (13)C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated.
authors.affiliation: Department of Physics, Women's Polytechnic College, Puducherry, India; Bharathiyar University, Coimbatore, Tamil Nadu, India. Electronic address: carthirohit@gmail.com.
authors.forename: K
authors.initials: K
authors.lastname: Carthigayan
authors.affiliation: Bharathiyar University, Coimbatore, Tamil Nadu, India; Department of Physics, St. Joseph College of Arts and Science, Cuddalore, Tamil Nadu, India.
authors.forename: S
authors.initials: S
authors.lastname: Xavier
authors.affiliation: Department of Physics, Tagore Arts College, Puducherry, India.
authors.forename: S
authors.initials: S
authors.lastname: Periandy
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D008958:Models, Molecular; D011720:Pyrazoles / Q000737:chemistry*; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013816:Thermodynamics
chemical_list: D011720:Pyrazoles
keywords: 3-Methyl-1-phenylpyrazole; Chemical shifts; HOMO–LUMO; NBO