Entity

Time filter

Source Type

Chennai, India

Ramya T.,Ctte College For Women | Ramya T.,Pachaiyappas College | Gunasekaran S.,St Peters University | Ramkumaar G.R.,C Kandaswami Naidu College For Men
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015

The experimental and theoretical spectra of (S)-2-Oxopyrrolidin-1-yl Butanamide (S2OPB) were studied. FT-IR and FT-Raman spectra of S2OPB in the solid phase were recorded and analyzed in the range 4000-450 and 5000-50 cm-1 respectively. The structural and spectroscopic analyses of S2OPB were calculated using ab initio Hartree Fock (HF) and density functional theory calculations (B3PW91, B3LYP) with 6-31G(d,p) basis set. A complete vibrational interpretation has been made on the basis of the calculated Potential Energy Distribution (PED). The HF, B3LYP and B3PW91 methods based NMR calculation has been used to assign the 1H NMR and 13C NMR chemical shift of S2OPB. Comparative study on UV-Vis spectral analysis between the experimental and theoretical (B3PW91, B3LYP) methods and the global chemical parameters and local descriptor of reactivity through the Fukui function were performed. Finally the thermodynamic properties of S2OPB were calculated at different temperatures and the corresponding relations between the properties and temperature were also studied. © 2015 Elsevier B.V. Source


Ramya T.,Ctte College For Women | Ramya T.,Pachaiyappas College | Gunasekaran S.,St Peters University | Ramkumaar G.R.,C Kandaswami Naidu College For Men
International Journal of Pharma and Bio Sciences | Year: 2015

Gabapentin purposefully synthesized to mimic the chemical structures of the neurotransmitter γ-aminobutyric acid and for use as an adjunctive medication to control partial seizures. In this work, the vibrational spectral analysis was carried out on Gabapentin by using FT-Raman and FTIR spectroscopy in the range 5000-50cm-1 and 4000-450cm-1respectively. Quantum chemical calculations of geometrical structure, vibrational wavenumber and infra red intensities were carried out by the ab inito Restricted Hartree Fock (RHF) and Density Functional Theory DFT (B3LYP) with complete relaxation in the potential energy surface using 6-311++G(d,p) basis set. The complete vibrational assignments of wave numbers were made on the basis of potential energy distribution (PED).The results of the calculations were applied to simulated spectra which shows good agreement with the observed spectra. Natural Population analysis (NPA), HOMO and LUMO energy, electric dipole moment(μ), hyperpolarizability(ß), chemical reactivity, 1H NMR and13C NMR and thermodynamic properties are also calculated using RHF and DFT methods. Source


Meenakshi R.,Ctte College For Women | Jagannathan L.,Ctte College For Women | Gunasekaran S.,Pachaiyappas College | Srinivasan S.,Ln Government College
Molecular Simulation | Year: 2010

Fourier transform infrared and Raman spectra of trimetazidine (TMZ) were recorded. The structure, geometry optimisation and vibrational frequencies were investigated. The specific mode of normal coordinate analysis was made for the stable conformer of the molecule using restricted Hartree-Fock (RHF) and density functional theory (DFT) calculations (B3LYP) with the 6-31G(d,p) basis set. Comparison of the observed fundamental vibrational frequencies of the molecule and calculated results by RHF and DFT methods indicates that B3LYP is superior to molecular vibrational problems. The thermodynamic functions of the title molecule were also calculated using the RHF and DFT methods. The DFT-optimised geometry was used in the time-dependent DFT and ZINDO calculations to predict the oscillator strength, electronic transition energies between the orbital and wavelength of the transitions. The DFT-based NMR calculation procedure was used to assign the 1H NMR chemical shift of TMZ. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in TMZ. © 2010 Taylor & Francis. Source


Meenakshi R.,Ctte College For Women | Jaganathan L.,Ctte College For Women | Gunasekaran S.,Pachaiyappas College | Srinivasan S.,Ln Government College
Molecular Simulation | Year: 2010

Fourier transform infrared and Raman spectra of nicorandil have been recorded. The structure, conformational stability, geometry optimisation and vibrational frequencies have been investigated. Complete vibrational assignments were made for the stable conformer of the molecule using restricted Hartree-Fock (RHF) and density functional theory (DFT) calculations (B3LYP) with the 6-31G(d,p) basis set. Comparison of the observed fundamental vibratioal frequencies of the molecule and calculated results by RHF and DFT methods indicates that B3LYP is superior for molecular vibrational problems. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. Natural bond order analysis of the title molecule was also carried out. Comparison of the simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibration modes. © 2010 Taylor & Francis. Source


Jagannathan L.,Ctte College For Women | Meenakshi R.,Ctte College For Women | Gunasekaran S.,Pachaiyappas College | Srinivasan S.,Ln Government College
Molecular Simulation | Year: 2010

The FT-IR and FT-Raman spectra of carvedilol were recorded in the regions 4000-400 and 3500-100cm-1, respectively. The electronic absorption spectrum was recorded in the region 400-200nm. In the present study, AM1 and PM3 semi-empirical molecular orbital methods were employed to study molecular structure as well as to predict infrared spectra. The AM1-optimised geometry was used in the density functional theory (DFT) calculation to predict the oscillator strength, electronic transition energies between the orbitals and wavelength of the transitions. The DFT-based NMR calculation procedure was used to assign the 1H NMR chemical shift of carvedilol. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in carvedilol. Source

Discover hidden collaborations