Perambalur, India
Perambalur, India

Time filter

Source Type

Balachandran V.,Aa Government Arts College | Karpagam V.,Srinivasan Polytechnic College | Lakshmi A.,Hh The Rajashs College
Journal of Molecular Structure | Year: 2012

The experimental and theoretical study on the structures and vibrations of 2,4,6-trihydroxybenzaldehyde (THB) is presented. The Fourier transform infrared spectra (4000-400 cm-1) and the Fourier transform Raman spectra (4000-50 cm-1) of the title molecule in the solid space have been recorded. The geometrical parameters and energies have been obtained for all 16 conformers from DFT (B3LYP) with 6-31+G(d,p) basis set calculations. There are 16 conformers, Cn = 1-16 for this molecule. The computational results identify the most stable conformer of THB as the C1 form. The vibrations of stable and unstable conformers of THB are researched with the aid of quantum chemical calculations. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The molecular structures and vibrational frequencies, infrared intensities and Raman scattering actives have been calculated. The optimized bond length, bond angles and calculated frequency showed the best agreement with experimental results. The formation of the hydrogen bond was investigated using NBO calculations. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. © 2012 Elsevier B.V. All rights reserved.


Balachandran V.,Arignar Anna Government Arts College | Karpagam V.,Srinivasan Polytechnic College
Journal of Molecular Structure | Year: 2013

FT-IR and FT-Raman spectra of 2,3-dihydroxybenzaldehyde (DHB) have been recorded in the regions 4000-400 cm-1 and 3500-100 cm-1, respectively. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) both B3LYP/6-31+G (d, p) and HF/6-31+G (d, p) basis sets combination. There are eight possible conformers (Cn, n = 1-8) for this molecule. The computational results identify the most stable conformer of DHB as the C6 form. The molecular structures, vibrational frequencies infrared intensities and Raman scattering activities were calculated. The spectroscopic and theoretical results are compared to the corresponding properties for DHB of C6 conformer. The optimized geometries and normal modes vibration obtained from DFT method are in good agreement with the experimental data. The formation of intermolecular hydrogen bond was investigated using NBO calculations. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule and ESP contour map shows the electrophilic and nucleophilic region of the molecule. © 2013 Elsevier B.V. All rights reserved.


Balachandran V.,AA Government Arts College | Karpagam V.,Srinivasan Polytechnic College | Rastogi V.K.,Aryan Institute of Technology
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2014

The FT-IR and Raman spectra of 2-amino-5-nitrobenzophenone (ANBP) molecule have been recorded using Brucker IFS 66 V spectrometer in the range of 4000-100 cm-1. The molecular geometry and vibrational frequencies in the ground state are calculated using the Hartree-Fock (HF) and B3LYP with 6-311+G(d) basis set. The computed values of frequencies are scaled using a suitable scale factor to yield good coherence with the observed values. The isotropic HF and DFT analysis showed good agreement with experimental observations comparison of the fundamental vibrational frequencies with calculated results by HF and B3LYP methods indicates that B3LYP/6-311+G(d) is superior to HF/6-311+G(d) for molecular vibrational problems. The electric dipole moment (μ) and first hyper polarizability (β) values of the investigated molecule were computed using density functional theory calculations. Stability of the molecule arising from hyperconjucative interactions leading to its bioactivity, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The calculated HOMO-LUMO energies shows that charge transfer occur within the molecule. The thermodynamic functions (heat capacity, internal heat energy, Gibbs energy and entropy) from spectroscopic data by statistical methods were obtained for the range of temperature 100-1000 K. The observed and calculated frequencies are found to be in good agreement. © 2013 Elsevier B.V. All rights reserved.


Balachandran V.,Center for Research | Karpagam V.,Srinivasan Polytechnic College
Journal of Molecular Structure | Year: 2013

FT-Raman and IR spectra of the biologically active molecule N-(p-methoxybenzylidene)aniline (NpMBA) have been recorded and analyzed. The molecular geometry of the title compound in the ground state have been calculated by density functional theory (DFT) with 6-31+G(d) and 6-311++G(d, p) basis sets. The harmonic vibrational frequencies calculated for NpMBA at B3LYP level using higher basis set 6-311++G(d, p). There are four conformers, C1, C2, C3 and C4 for this molecule. The computational results diagnose the most stable conformer of NpMBA as the C4 form. In order to obtain the information about the influence of intramolecular interaction on the molecule the calculated geometries of NpMBA molecule was compared with experimental data. The results of the optimized molecular structure gave clear evidence for the intramolecular charge transfer (ICT). The electric dipole moment (l) and first hyper polarizability (b) values of the investigated molecule were computed using density functional theory calculations. The calculated results also show that the NpMBA molecule might have microscopic non-linear optical (NLO) behavior with non-zero values. The effects of methoxy and central bond substituent in benzene ring in the vibrational wave numbers have been analyzed. NBO analysis is useful to understand the intra molecular hyper conjugative interaction between lone pair N and rσ(C-C) bond orbital. The overlapping of atomic orbitals along with their predicted energy is explained on the basis of HOMO-LUMO energy gap calculations. The MEP surface and thermodynamic parameters are also predicted. © 2013 Elsevier B.V. All rights reserved.


Balachandran V.,Arignar Anna Government Arts College | Karpagam V.,Srinivasan Polytechnic College
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The FT-IR and Raman spectra of 2, 6-dichloro-3-nitrobenzoic acid (DCNBA) have been recorded and analyzed. The equilibrium geometry, various bonding and harmonic vibrational wavenumbers have been calculated with the help of density functional theory (DFT/B3LYP/cc-pvdz/6-311++G(d,p)) method. The optimized geometrical parameters obtained by B3LYP/6-311++G(d,p) method show good agreement with experimental X-ray data. Most of the vibrational modes are observed in the expected range. The Mulliken population analysis shows the interactions of CNOâ̄HC and COâ̄HC. The most possible interaction is explained using natural bond orbital (NBO) analysis. The effects of molecular association through OHâ̄O hydrogen bonding have been described by the single dimer structure. The strengthening and polarization of the CO bond increases due to the degree of conjugation. HOMO-LUMO energy and the thermodynamic parameters are also evaluated. The thermodynamic functions (heat capacity, internal heat energy, Gibbs energy and entropy) from spectroscopic data by statistical methods were obtained for the range of temperature 100-1000 K. © 2013 Elsevier B.V. All rights reserved.


Balachandran V.,A A Government Arts College | Karpagam V.,Srinivasan Polytechnic College
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The (FT-IR and FT-Raman) spectral properties of 5-bromo-2- methoxybenzaldehyde (BMB) are studied using density functional theory (DFT) employing B3LYP/6-311++G (d) and B3LYP/6-311++G (d, p) levels of theory. There are four conformers, C1, C2, C3, and C4 for this molecule. The computational results diagnose the most stable conformer of BMB as the C1 form. The optimized geometrical parameters obtained by B3LYP/6-311++G (d, p) method show good agreement with experimental X-ray data. A study on the electronic properties, such as HOMO and LUMO energies, is performed. The isotropic chemical shift computed by 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the BMB calculated using the gauge invariant atomic orbital (GIAO) method also shows good agreement with experimental observations. The MEP surface reflects the chemical reactivity of a molecule. The thermodynamic functions (heat capacity, internal heat energy, Gibbs energy and entropy) from spectroscopic data by statistical methods were obtained for the range of temperature 100-1000 K. The energetic behavior of the compound in different solvent medium (water, ethanol, and methanol) was examined by applying polarizable continuum model (PCM). The complete molecular orbital simulations and theoretical UV-visible spectra carried out in this study yield better understanding of charge delocalization pattern and stability of the title molecules to a greater extent. © 2013 Elsevier B.V. All rights reserved.


Balachandran V.,Center for Research | Karpagam V.,Srinivasan Polytechnic College | Revathi B.,Center for Research | Karabacak M.,Celal Bayar University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015

The optimized molecular structure and corresponding vibrational assignments of 2-tert-butyl-5-methyl anisole (TBMA) have been investigated using density functional theory (DFT)/B3LYP with 6-31G(d,p) and 6-311++G(d,p) basis sets investigation of the relative orientation of the methoxy group has shown two conformers (O-cis) and (O-trans) exist. The vibrational analysis of the stable conformer of the title compound is performed by means of infrared absorption and Raman spectroscopy in combination with theoretical simultaneously. The natural bond orbital (NBO) analysis is useful to understand the intra-molecular hyper conjugative interaction lone pair and π∗(CC), σ∗(CH) bond orbital. HOMO and LUMO energies show that charge transfer occurs in the molecule, therefore; HOMO, LUMO and molecular electrostatic potential (MEP) were calculated and analyzed. 1H and 13C NMR spectra by using gauge including atomic orbital (GIAO) method of studied compound were compared with experimental data. The thermodynamic functions of TBMA were calculated by B3LYP/6-311+G(d,p) basis set. © 2014 Elsevier B.V. All rights reserved.

Loading Srinivasan Polytechnic College collaborators
Loading Srinivasan Polytechnic College collaborators