K. Parimala

Mookambigai College of Engineering, Pudukotah, Tamil Nādu, India

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Publications (9)11.29 Total impact

  • K Parimala, V Balachandran
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    ABSTRACT: In this work, the vibrational spectral analysis was carried out by FT-IR and FT-Raman spectroscopy in the regions of 4000-400cm(-1) and 3500-100cm(-1), respectively for 2',4'-difluoroacetophenone (DFAP). The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartree-Fock (HF), density functional theory (DFT) using B3LYP and LSDA methods with 6-31G basis set combination. The mixing of the fundamental modes was determined with the help of potential energy distribution (PED). The energies of the frontier molecular orbitals have also been determined. Complete NBO analysis was also carried out using B3LYP/6-31G level of theory to find out the intramolecular electronic interactions and their stabilization energy. Thermodynamic properties of the title compound were calculated at the different temperature. Finally, the calculation results were applied to simulate FT-IR and FT-Raman spectra of the title compound which show good agreement with observed spectra.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2013; 110C:269-284. · 1.98 Impact Factor
  • V Balachandran, K Parimala
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    ABSTRACT: The keto-enol tautomerism of 2-amino-4-pyrimidinol (APN) and 2-amino-pyrimidine-4(1H)-one (APO) are investigated by vibrational spectroscopy and quantum chemical method. FT-IR and FT-Raman spectra are recorded in the regions of 4000-400cm(-1) and 3500-100cm(-1), respectively for APN. Geometrical parameters, vibrational wavenumbers of APN and APO are predicted by density functional theory (DFT) employing B3LYP level with 6-311++G(d,p) and 6-311++G(2d,p) basis sets. The non-linear optical (NLO) properties of the title molecules are computed. The molecular electrostatic potential (MEP) surface maps are plotted and explained in detail. Natural bond orbital (NBO) analyses have been performed on APN molecule. The significant changes in occupancies and the energies of bonding and antibonding orbital have been explained in detail. Thermodynamic properties (heat capacities, entropies, and enthalpy) and their correlations with temperatures are also obtained from the calculated frequencies of the optimized structures. Reactivity descriptors, Fukui functions and electrophilic sites are found and discussed.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 10/2012; 102C:30-51. · 1.98 Impact Factor
  • V. Balachandran, K. Parimala
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    ABSTRACT: Two purine tautomers of 2-amino-6-chloropurine (ACP), in labeled as N9H10 and N7H10, were investigated by vibrational spectroscopy and quantum chemical method. The FT-IR and FT-Raman spectra of ACP have been recorded in the regions 4000–400 cm−1 and 3500–100 cm−1, respectively. The measured spectra were interpreted by aid of a normal coordinate analysis following DFT full geometry optimization and vibrational frequency calculations at B3LYP/6-311++G(d,p) level. First-order hyperpolarizability, HOMO and LUMO energies were calculated at same level of theory. The calculated molecular geometry has been compared with the X-ray data. The observed and calculated frequencies were found in good agreement. The obtained NBO data and second-order perturbation energy values to elucidate the Lewis and non-Lewis types of bonding structures in the purine tautomer N9H10, have indicated the presence of an intramolecular hyperconjucative interaction between lone pair N and N–C bond orbital.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 05/2012; 96:340–351. · 1.98 Impact Factor
  • V Balachandran, K Parimala
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    ABSTRACT: This study is a comparative analysis of FT-IR and FT-Raman spectra of vanillin (3-methoxy-4-hydroxybenzaldehyde) and isovanillin (3-hydroxy-4-methoxybenzaldehyde). The molecular structure, vibrational wavenumbers, infrared intensities, Raman scattering activities were calculated for both molecules using the B3LYP density functional theory (DFT) with the standard 6-311++G(∗∗) basis set. The computed values of frequencies are scaled using multiple scaling factors to yield good coherence with the observed values. The calculated harmonic vibrational frequencies are compared with experimental FT-IR and FT-Raman spectra. The geometrical parameters and total energies of vanillin and isovanillin were obtained for all the eight conformers (a-h) from DFT/B3LYP method with 6-311++G(∗∗) basis set. The computational results identified the most stable conformer of vanillin and isovanillin as in the "a" form. Non-linear properties such as electric dipole moment (μ), polarizability (α), and hyperpolarizability (β) values of the investigated molecules have been computed using B3LYP quantum chemical calculation. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecules.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 04/2012; 95:354-68. · 1.98 Impact Factor
  • National Seminar on Advances in Materials Science, Manonmaiam Sundaranar University, Tirunelveli, Tamil Nadu, India; 01/2012
  • V. Balachandran, K. Parimala
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    ABSTRACT: The FT-IR and FT-Raman vibrational spectra of mesityl chloride (2,4,6-trimethylbenzyl chloride) were recorded. The optimized geometry and wavenumbers in the ground state were calculated using density functional (B3LYP, and B3PW91) methods with standard 6-311G(d,p) basis set. The computed B3PW91/6-311G(d,p) results show the best agreement with the experimental values over the other methods. Natural bond orbital analysis of mesityl chloride is also carried out, which confirms the occurrence of strong intermolecular bonding, stability of the molecule arising from hyperconjugative interactions, and charge delocalization. The electric dipole moment (μ), polarizability (α), and first hyperpolarizability (β0) which results also show that the mesityl chloride might have microscopic non-linear optical behavior with non-zero values. The calculated HOMO and LUMO energies show that charge transfer occur in the molecule. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra.
    Journal of Molecular Structure 01/2012; 1007:136–145. · 1.40 Impact Factor
  • K Parimala, V Balachandran
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    ABSTRACT: The Fourier transform infrared (FTIR) and FT Raman spectra of p-toluenesulfonyl isocyanate (p-tosyl isocyanate) have been measured. The molecular geometry, vibrational frequencies, infrared intensities, Raman activities and atomic charges have been calculated by using ab initio HF and density functional theory calculation (B3LYP) with 6-311+G(d,p) basis set. Complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FTIR and FT Raman data. The thermodynamic functions of the title compound were also performed with the aid of HF/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory. Simulated FTIR and FT Raman spectra for p-tosyl isocyanate showed good agreement with the observed spectra. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The dipole moment (μ), polarizability (α) and the hyperpolarizability (β) values of the investigated molecule have been computed using HF and B3LYP methods.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 07/2011; 81(1):711-23. · 1.98 Impact Factor
  • K. Parimala, V. Balachandran
    International Conference on Recent Frontiers in Applied Spectroscopy (ICORFAS-2010), Annamalai University, Tamil Nadu; 09/2010
  • UGC sponsored National conference on Recent and Emerging Developments in Physics, Women's Christian College for Women, Nagarcoil, Tamil Nadu, India; 01/2010

Publication Stats

10 Citations
11.29 Total Impact Points

Top co-authors

Institutions

  • 2011–2013
    • Mookambigai College of Engineering
      Pudukotah, Tamil Nādu, India
  • 2012
    • A.A.Government Arts College Musiri
      Musiri, Tamil Nādu, India