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In the present work the structural and spectral characteristics of 5-benzyl-2-thiohydantoin (5-BTH) have been studied by methods of infrared, Raman spectroscopy and quantum chemistry. Electrostatic potential surface, optimized geometry, harmonic vibrational frequencies, infrared intensities and activities of Raman scattering were calculated by density functional theory (DFT) employing B3LYP with complete relaxation in the potential energy surface using 6-311G++(d,p) basis set. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. UV-vis spectrum of the compound was recorded in methanol solvent. The TD-DFT calculations have been performed to explore the influence of electronic absorption spectra in the gas phase, as well as in solution environment using PCM and 6-311++G(d,p) basis set. In addition, the thermodynamic properties of the compound were calculated at different temperatures and corresponding relations between the properties and temperature were also studied. [ABSTRACT FROM AUTHOR]

Highlights: [•] FT-IR spectrum of synthesized compound recorded and compared with the theoretical results. [•] By using TD-DFT/6-31G method, electronic transitions for title compound are predicted. [•] The 1HNMR spectrum has also been studied. [•] The electronic descriptors have been used to explain chemical reactivity. [Copyright &y& Elsevier]

Highlights: [•] FT-IR spectrum of the studied compound has been compared with the theoretical results. [•] The resonance assisted intramolecular hydrogen bonds has been characterized using AIM calculations.. [•] The electronic transitions for the synthesized compound have been predicted. [•] The 1H NMR spectrum for title compound has been studied.. [•] Chemical reactivity has been explained with the aid of electronic descriptors. [Copyright &y& Elsevier]

Highlights: [•] FT-IR spectrum of the studied compound was recorded and compared with the theoretical result. [•] All the theoretical calculations were made using DFT/B3LYP/6-31G(d,p) method. [•] NBO analysis are performed to determine the hyperconjugative interactions. [•] QTAIM analysis are performed to determine hydrogen bonding. [•] Chemical reactivity has been explained with the aid of electronic descriptors. [Copyright &y& Elsevier]

Abstract: A new ethyl-4-{[(2,4-dinitrophenyl)-hydrazono]-ethyl}-3,5-dimethyl-1H-pyrrole-2-carboxylate (EDPHEDPC) has been synthesized and characterized by FT-IR, 1H NMR, UV–vis, DART-Mass spectroscopy and elemental analysis. Quantum chemical calculations have been performed by DFT level of theory using B3LYP functional and 6-31G(d,p) as basis set. The 1H NMR chemical shifts are calculated using gauge including atomic orbitals (GIAO) approach in DMSO as solvent. The time dependent density functional theory (TD-DFT) is used to find the various electronic transitions and their nature within molecule. A combined theoretical and experimental wavenumber analysis confirms the existence of dimer. Topological parameters such as electron density (ρ BCP), Laplacian of electron density (▿2 ρ BCP), kinetic electron energy density (G BCP), potential electron density (V BCP) and the total electron energy density (H BCP) at bond critical points (BCP) have been analyzed by Bader''s ‘Atoms in molecules’ AIM theory in detail. The intermolecular hydrogen bond energy of dimer is calculated as −12.51kcal/mol using AIM calculations. AIM ellipticity analysis is carried out to confirm the presence of resonance assisted intra and intermolecular hydrogen bonds in dimer. The calculated thermodynamic parameters show that reaction is exothermic and non-spontaneous at room temperature. The local reactivity descriptors such as Fukui functions (f k +, f k −), local softnesses (s k −, s k +) and electrophilicity indices (ω k +, ω k −) analyses are performed to determine the reactive sites within molecule. Nonlinear optical (NLO) behavior of title compound is investigated by the computed value of first hyperpolarizability (β 0). [Copyright &y& Elsevier]

Abstract: A new ethyl 4-formyl-3,5-dimethyl-1H-pyrrole-2-carboxylate thiosemicarbazone (EFDMPCT) has been synthesized and characterized by elemental analysis and FT-IR, 1H NMR, UV–Visible, DART-mass spectroscopy. Quantum chemical calculations have been performed by DFT level of theory using B3LYP functional and 6-31G (d,p) as basis set. The calculated 1H NMR chemical shifts using gauge including atomic orbitals (GIAO) approach are in good agreement with the observed chemical shifts. The electronic transitions within molecule have been interpreted using the time dependent density functional theory (TD-DFT). The calculated and experimental wavenumbers analyses confirm the existence of dimer. Topological parameters electron density, Laplacian of electron density, kinetic electron energy density, potential electron density and the total electron energy density at the bond critical points (BCP) analyzed using ‘Atoms in Molecules’ AIM theory reveals intra and inter molecular hydrogen bonding other weaker interactions in detail. The calculated intermolecular hydrogen bond energy of dimer is −12.2176kcal/mol using AIM calculation. The results of AIM ellipticity confirm the existence of resonance assisted hydrogen bonds in dimer. The calculated thermodynamic parameters show that reaction is exothermic and non-spontaneous at room temperature. The local reactivity descriptors find the reactive sites within molecules have been calculated. [Copyright &y& Elsevier]