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Meenakshi R.,Ctte College | Jaganathan L.,Ctte College | Gunasekaran S.,Pachaiyappas College | Gunasekaran S.,Periyar University | Srinivasan S.,Ln Government College
Molecular Simulation | Year: 2012

The Fourier transform Raman (FT-Raman) and Fourier transform infrared (FTIR) spectra for nitroglycerin (NG) in the solid phase have been recorded in the region 4000-100 and 4000-400cm 1, respectively, compared with the harmonic vibrational frequencies calculated using density functional theory (DFT) (B3PW91) method by employing 6-311G (d,p) basis set with appropriate scale factors. Optimised geometries of the molecule have been interpreted and compared with the reported experimental values. The experimental geometrical parameters show satisfactory agreement with the theoretical prediction from DFT. The scaled vibrational frequencies seem to coincide with the experimentally observed values with acceptable deviations. The theoretical spectrograms (IR and Raman) have been constructed and compared with the experimental FTIR and FT-Raman spectra. Also we have investigated the effect of ionisation in the geometries and infrared spectrum of NG. A significant reduction in intensities and wave number shifts have been identified on ionised NG and discussed. The calculated atomic charges from natural population analysis were used to predict the chemical reactive sites in NG. © 2012 Copyright Taylor and Francis Group, LLC. Source

Jaganathan L.,Ctte College | Meenakshi R.,Ctte College | Gunasekaran S.,Pachaiyappas College | Srinivasan S.,Ln Government College
Molecular Simulation | Year: 2011

Fourier transform infrared and Raman spectra of nebivolol have been recorded. The structure, conformational stability, geometry optimisation, and vibrational wave numbers have been investigated. Satisfactory vibrational assignments were made for the stable conformer of the molecule using Restricted Hartree-Fock (RHF) and density functional theory (DFT) calculation (B3LYP) with the 6-31G(d,p) basis set. Comparison of the observed fundamental vibrational wave numbers of the molecule and calculated results by RHF and DFT methods indicates that B3LYP is superior for molecular vibrational problems. Comparison of the simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. The RHF and DFT-based NMR calculation procedure was also done. It was used to assign the 13C NMR chemical shift of nebivolol. © 2011 Taylor & Francis. Source

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