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Srinivasan P.,C Kandaswami Naidu College For Men | Stephen A.D.,Coimbatore Institute of Technology
Journal of Theoretical and Computational Chemistry | Year: 2015

The electron density and conductivity studies of 2,5-diphenyl-1,3,4-oxadizole organic light emitting diode (OLED) based molecule have been calculated from the quantum chemical calculations and combined with the Bader's AIM theory. Density functional theory calculations with B3LYP/aug-cc-PVDZ basis sets was used to determine ground state gas space molecular geometries (bond lengths and bond angles), electron density and bonding features of this molecule. The electron densities at the bond critical point (BCP) of aromatic Car-Car bonds are much stronger than the other bonds in the molecule. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The HOMO-LUMO gap calculated from quantum chemical calculations has been compared with the value calculated from the density of states. The negative electrostatic potential (ESP) is concentrated solely around the N atoms, whereas in the rest of the region a positive ESP to dominate. © 2015 World Scientific Publishing Company.


Arputhara D.S.,Coimbatore Institute of Technology | Nidhin P.V.,Coimbatore Institute of Technology | Srinivasan P.,C Kandaswami Naidu College For Men
Journal of the Serbian Chemical Society | Year: 2016

A validation study to predict the possible stable polymorphs of pyrazinamide within the low energy conformational region of the flexible torsion angle was performed through a potential energy surface (PES) scan by gas phase optimisation using the MP2/6-31G(d,p) method. Hypothetical crystal structures with favourable packing density for each of the stable conformers generated from the PES scan were generated using a global search with a repulsion only potential field. The densest crystal structures with stable energy were analyzed with more accurate lattice energy minimisation via distributed multipole analysis using the repulsion-dispersion potential. The stability of the predicted crystal structures with similar close packing to the known experimental polymorphs of the pyrazinamide molecule were analyzed by inspecting their intermolecular short contacts. Studies to analyze the second derivative mechanical properties from the Hessian matrix were realised to emphasise the thermodynamic stability of predicted polymorphs of pyrazinamide. © 2016, Serbian Chemical Society. All rights reserved.


Madhusoodhanan P.,SRM University | Sekar P.,C Kandaswami Naidu College For Men | Ramanarayanan R.,Tamil University
International Journal of Applied Engineering Research | Year: 2015

A production and sale system is considered. During the operation time a machine produces random number of products. After operation time, sale time starts. Two models are treated. In model 1, the sales time of production is i. i. d random variables, when production is stopped and sales are done one by one. In model 2, the operation time is more than a threshold time, the sales are done altogether and when it is less than the threshold time, the sales are done one by one. Joint transforms of the variables, their means and Co-variances with numerical results are presented. © Research India Publications.


Latha B.,Dr. M.G.R. Educational and Research Institute | Latha B.,SCSVMV University | Gunasekaran S.,St Peters University | Srinivasan S.,Presidency College at Chennai | Ramkumaar G.R.,C Kandaswami Naidu College For Men
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2014

The solid phase FTIR and FT-Raman spectra of Losartan have been recorded in the region 400-4000 cm-1. The spectra were interpreted in terms of fundamental modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by Quantum chemical methods. The vibrational frequencies yield good agreement between observed and calculated values. The infrared and Raman spectra were also predicted from the calculated intensities. (1)H and (13)C NMR spectra were recorded and resonance chemical shifts of the molecule were calculated. UV-Visible spectrum of the compound was recorded in the region 200-600 nm and the electronic properties HOMO and LUMO energies calculated by TD-HF approach. NBO atomic charges of the molecules and second order perturbation theory analysis of Fock matrix also calculated and interpreted. The geometrical parameters, energies, harmonic vibrational frequencies, IR intensities, Raman intensities, and absorption wavelengths were compared with experimental and theoretical data of the molecule. © 2014 Elsevier B.V. All rights reserved.


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.


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.


Boopathi M.,Pachaiyappas College for Men | Boopathi M.,Dr. M.G.R. Educational and Research Institute | Udhayakala P.,Dr. M.G.R. Educational and Research Institute | Ramkumaar G.R.,C Kandaswami Naidu College For Men
Der Pharma Chemica | Year: 2016

This work presents the characterization of 5-[(3,5-dimethylphenoxy)methyl]-1,3-oxazolidin-2-one (metaxalone) by DFT calculations and spectral techniques. The spectral analysis was carried out by using FT-IR and FT-Raman and 13C and 1H nuclear magnetic resonance (NMR) techniques. The FT-IR and FT-Raman spectrum were recorded in the range of 4000 to 400cm-1 and 4000 to 50cm-1 respectively. The over estimations of the calculated harmonic wavenumbers were efficiently corrected by the aid of a specific scaling procedure. 13C and 1H NMR chemical shifts of the molecule were calculated using gauge independent atomic orbital method (GIAO) and were compared with the experimental results. The molecular structure, fundamental vibrational frequencies and electronic structure calculations are carried out by density functional theory (DFT) method and B3LYP/ 6-311++G(d,p) basis set. Frontier molecular orbital energies, global reactivity descriptors and molecular electrostatic potential (MEP) were estimated. The thermodynamic properties at different temperatures were calculated revealing the correlations between standard heat capacities, entropy and enthalpy changes with temperatures.


Gnanasekaran P.,Loyola College | Gnanasekaran P.,C Kandaswami Naidu College For Men | Madhavan J.,Loyola College
Asian Journal of Chemistry | Year: 2010

Single crystals of pure and La3+ doped L-arginine acetate have been successfully grown from aqueous solution by slow evaporation technique. The grown crystals were confirmed by powder X-ray diffraction studies. The optical properties of the crystals were studied by FT-IR and UV-Vis-NIR spectral techniques and the influence of the La3+ is reported. The second harmonic generation efficiencies of the crystals were confirmed by Kurtz and Perry powder technique.


Kumar J.S.,P.A. College | Kumar J.S.,Periyar University | Devi T.S.R.,Womens Christian College | Ramkumaar G.R.,C Kandaswami Naidu College For Men | Bright A.,P.A. College
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2016

Abstract The FTIR and FT-Raman spectra of 4-(2-Hydroxyethyl) piperazine-1-ethanesulfonic acid were recorded and the structural and spectroscopic data of the molecule in the ground state were calculated using Hartree-Fock and Density Functional Method (B3LYP). The most stable conformer was optimized and the structural and vibrational parameters were determined. With the observed FTIR and FT-Raman data, a complete vibrational band assignment and analysis of the fundamental modes of the compound were carried out. Thermodynamic properties, Mulliken and natural atomic charge distribution were calculated using both Hartree-Fock and Density Functional Method and compared. UV-Visible and HOMO-LUMO analysis were carried out. 1H and 13C NMR chemical shifts of the molecule were calculated using gauge including atomic orbital method and were compared with experimental results. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. The first order hyperpolarizability (β) and molecular electrostatic potential of the molecule was computed using DFT calculations. The electron density based local reactivity descriptor such as Fukui functions were calculated to explain the chemically reactive site in the molecule. © 2015 Elsevier B.V.


PubMed | P.A. College, C Kandaswami Naidu College For Men, Womens Christian College and Periyar University
Type: | Journal: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy | Year: 2015

The FTIR and FT-Raman spectra of 4-(2-Hydroxyethyl) piperazine-1-ethanesulfonic acid were recorded and the structural and spectroscopic data of the molecule in the ground state were calculated using Hartree-Fock and Density Functional Method (B3LYP). The most stable conformer was optimized and the structural and vibrational parameters were determined. With the observed FTIR and FT-Raman data, a complete vibrational band assignment and analysis of the fundamental modes of the compound were carried out. Thermodynamic properties, Mulliken and natural atomic charge distribution were calculated using both Hartree-Fock and Density Functional Method and compared. UV-Visible and HOMO-LUMO analysis were carried out. (1)H and (13)C NMR chemical shifts of the molecule were calculated using gauge including atomic orbital method and were compared with experimental results. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. The first order hyperpolarizability () and molecular electrostatic potential of the molecule was computed using DFT calculations. The electron density based local reactivity descriptor such as Fukui functions were calculated to explain the chemically reactive site in the molecule.

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