title: Quantum-chemical (DFT, MP2) and spectroscopic studies (FT-IR and UV) of monomeric and dimeric structures of 2(3H)-Benzothiazolone.
abstract: Molecular geometry and vibrational wavenumbers of 2(3H)-Benzothiazolone (C7H5NSO, HBT) was investigated using density functional (DFT/B3LYP) method with 6-311+G(d,p) basis set. The vibrational wavenumbers are found to be in good agreement with experimental FT-IR spectra. Hydrogen-bonded dimer of HBT, optimized by counterpoise correction, was studied by MP2 and DFT/B3LYP at the 6-311+G(d,p) level and the effects of molecular association through NH---O hydrogen bonding were discussed. A detailed analysis of the nature of the hydrogen bonding, using topological parameters, such as electronic charge density, Laplacian, kinetic and potential energy density evaluated at bond critical points (BCP) has also been presented. The UV absorption spectra of the compound dissolved in ethanol and chloroform solutions were recorded in the range of 200-600 nm. The UV-vis spectrum of the title molecule was also calculated using TD-DFT method. The calculated energy and oscillator strength almost exactly reproduce the experimental data. Total and partial density of state (TDOS, PDOS) of the HBT in terms of HOMOs and LUMOs and molecular electrostatic potential (MEP) were calculated and analyzed. The electric dipole moment, polarizability and the first static hyper-polarizability values for HBT were calculated at the DFT/B3LYP with 6-311+G(d,p) basis set. The results also show that the HBT molecule may have nonlinear optical (NLO) comportment with non-zero values. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization was analyzed using natural bond orbital (NBO) analysis.
authors.affiliation: Department of Physics, University of Lucknow, 226007 Lucknow, India.
authors.forename: L
authors.initials: L
authors.lastname: Sinha
authors.affiliation: Department of Physics, University of Lucknow, 226007 Lucknow, India.
authors.forename: O
authors.initials: O
authors.lastname: Prasad
authors.affiliation: Department of Mechatronics Engineering, H.F.T. Technology Faculty, Celal Bayar University, 45400 Turgutlu, Manisa, Turkey. Electronic address: mehmet.karabacak@cbu.edu.tr.
authors.forename: M
authors.initials: M
authors.lastname: Karabacak
authors.affiliation: Department of Physics, University of Lucknow, 226007 Lucknow, India.
authors.forename: H N
authors.initials: HN
authors.lastname: Mishra
authors.affiliation: Department of Physics, University of Lucknow, 226007 Lucknow, India.
authors.forename: V
authors.initials: V
authors.lastname: Narayan
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia; Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: A M
authors.initials: AM
authors.lastname: Asiri
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry*; D019281:Dimerization; D008958:Models, Molecular; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D052160:Benzothiazoles
keywords: 2(3H)-Benzothiazolone; Critical points; Hydrogen bonded dimer; NBO analysis; NLO; Vibrational analysis