Browsing by Author "Chand S."

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    FT-IR, FT-Raman and UV spectroscopic investigation, electronic properties, electric moments, and NBO analysis of anethole using quantum chemical calculations
    (Elsevier, 2014) Sinha L.; Prasad O.; Chand S.; Sachan A.K.; Pathak S.K.; Shukla V.K.; Karabacak M.; Asiri A.M.
    FT-IR and FT-Raman spectra of anethole (1-Methoxy-4-(1-propenyl)benzene), a flavoring agent of commercial value, have been recorded in the regions 4000-400 and 4000-100 cm-1 respectively. The structure of the title molecule has been optimized and the structural parameters have been calculated by DFT/B3LYP method with 6-311++G(d,p) basis set. The fundamental vibrational wavenumbers as well as their intensities were calculated and a good agreement between observed and scaled calculated wavenumbers has been achieved. UV-Vis spectrum of the title compound was recorded in the region 200-500 nm and the electronic properties such as HOMO and LUMO energies and associated energy gap were calculated by Time dependent-density functional theory (TD-DFT) approach. Nonlinear optical (NLO) study divulges the nonlinear properties of the molecule. Stability of the title molecule arising from hyper-conjugative interactions and charge delocalization has been investigated using natural bond orbital (NBO) analysis. The theoretical results were found to be in coherence with the measured experimental data. © 2014 Elsevier B.V. All rights reserved.
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    Conformational and spectroscopic behaviors of 2,4-xylyl isothiocyanate
    (Elsevier, 2015) Cinar M.; Karabacak M.; Chand S.; Shukla V.K.; Sinha L.; Prasad O.; Singh M.P.; Asiri A.M.
    This study aims to identify the conformational and spectroscopic characteristics of 2,4-xylyl isothiocyanate (C9H9NS) compound via experimental and computational methods. To accomplish this, density functional theory (DFT), with the B3LYP functional was used to determine ground state conformation, vibrational wavenumbers and also isotropic chemical shifts of the title molecule. Experimentally, vibrational features of the compound were evaluated by FT-IR and FT-Raman spectroscopic analysis in the solid phase. On the basis of these studies, the conformational and spectroscopic behaviors of 2,4-xylyl isothiocyanate were interpreted. The fundamental vibrational wavenumbers as well as their intensities were computed, and a good correlation between experimental and scaled calculated wavenumbers was observed. The polarizability, first hyperpolarizability and dipole moment values of 2,4-xylyl isothiocyanate were calculated at the same level of theory and basis set. The results show that 2,4-xylyl isothiocyanate molecule possesses nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization was analyzed using natural bond orbital (NBO) analysis. ©2015 Elsevier B.V. All rights reserved.
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    A combined experimental and theoretical DFT (B3LYP, CAM-B3LYP and M06-2X) study on electronic structure, hydrogen bonding, solvent effects and spectral features of methyl 1H-indol-5-carboxylate
    (Elsevier B.V., 2017) Srivastava R.; Al-Omary F.A.M.; El-Emam A.A.; Pathak S.K.; Karabacak M.; Narayan V.; Chand S.; Prasad O.; Sinha L.
    Investigation of ground state geometry, molecular properties and electronic structure of methyl 1H-indol-5-carboxylate has been reported for the first time using the implements of density functional theory. The two possible conformers of the title compound were first optimized at B3LYP/6-31G(d) and then further at B3LYP, M06-2X and CAM-B3LYP functionals at 6-311++G(d,p) basis set. A comprehensive vibrational analysis has been performed for both the conformers at B3LYP/6-311++G(d,p). Good agreement between theoretical spectral data with experimental spectra has been obtained. Polarizability and first static hyperpolarizability have been compared at different functionals used in the present study. To estimate the intra-molecular delocalization along with the inter-molecular interaction, the NBO analysis has been done for monomer and dimer of the title molecule. Topological parameters at the bond critical point involved in intermolecular hydrogen-bonding have also been calculated using AIM theory to assess the strength of hydrogen bonding. Effects of solvents (water, carbon tetrachloride and chloroform) on the optimized geometry and the inter-molecular hydrogen bonding have been evaluated. UV–Vis spectrum of the title compound was also recorded and electronic properties such as frontier orbitals and their corresponding energy gap have also been calculated by TD-DFT approach. © 2017 Elsevier B.V.