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Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Isaac A.S.R.,Madurai Kamaraj University | Rani T.,University | Mythili C.V.,Rani Anna Government College for Women | Mohan S.,Hawasa University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

The Fourier transform infrared (FTIR) and FT-Raman spectra of 2-chloro-6-methoxypyridine have been recorded in the range 3700-400 and 3700-100 cm-1, respectively. The complete vibrational assignment and analysis of the fundamental modes of the compound was carried out using the observed FTIR and FT-Raman data. The vibrational frequencies determined experimentally were compared with the theoretical frequencies computed by DFT gradient calculations (B3LYP method) employing the 6-31G(d,p), cc-pVTZ and/6-311++G(d,p) basis sets for the optimised geometry of the compound. The geometry and normal modes of vibration obtained from the DFT methods are in good agreement with the experimental data. The normal co-ordinate analysis was also carried out using DFT force fields utilising Wilson's FG matrix method. The influence of the substituents bulky chlorine atom and the methoxy group on the spectral characteristics of the compound has been discussed. The electronic spectrum determined by TD-DFT method is compared with the observed electronic spectrum. © 2011 Elsevier B.V. All rights reserved. Source


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Rani T.,University | Mythili C.V.,Rani Anna Government College for Women | Mohan S.,Hawasa University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

A systematic vibrational spectroscopic assignment and analysis of benzohydrazide (BH) has been carried out by using FTIR and FT-Raman spectral data. The vibrational analysis were aided by electronic structure calculations - ab initio (RHF) and hybrid density functional methods (B3LYP and B3PW91) performed with 6-31G(d,p) and 6-311++G(d,p) basis sets. Molecular equilibrium geometries, electronic energies, IR intensities, harmonic vibrational frequencies, depolarization ratios and Raman activities have been computed. Potential energy distribution (PED) and normal mode analysis have also been performed. The assignments proposed based on the experimental IR and Raman spectra have been reviewed and complete assignment of the observed spectra have been proposed. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λmax were determined by time-dependent DFT (TD-DFT) method. The geometrical, thermodynamical parameters and absorption wavelengths were compared with the experimental data. The interactions of carbonyl and hydrazide groups on the benzene ring skeletal modes were investigated. © 2011 Elsevier B.V. All rights reserved. Source


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Sakiladevi S.,Ar Engineering College | Mythili C.V.,Rani Anna Government College for Women | Mohan S.,Hawasa University Main Campus
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2012

The FT-IR (4000-400 cm -1) and FT-Raman (4000-100 cm -1) spectral measurements and complete assignments of the observed spectra of 2-amino-4-methylbenzothiazole (2A4MBT) have been proposed. Ab initio and DFT calculations have been performed and the structural parameters of the compound were determined from the optimised geometry with 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets and giving energies, harmonic vibrational frequencies, depolarisation ratios, IR intensities and Raman activities. 1H and 13C NMR spectra were recorded and 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO, LUMO and band gap energies were measured by time-dependent DFT (TD-DFT) approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman activities chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule. The influences of methyl and amino groups on the skeletal modes and on the proton chemical shifts have been investigated. © 2011 Elsevier B.V. All rights reserved. Source


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Balamourougane P.S.,University | Mythili C.V.,Rani Anna Government College for Women | Mohan S.,Hawasa University
Journal of Molecular Structure | Year: 2011

The solid phase FTIR and FT-Raman spectra of 2-amino-5-chlorobenzoxazole have been recorded in the regions 4000-400 and 3500-100 cm-1, respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The normal coordinate analysis was carried out to confirm the precision of the assignments. The structure of the compound was optimised and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets. The molecular properties were also determined by HF/6-311++G(d,p) level. The vibrational frequencies were calculated in all these methods and were compared with the experimental frequencies which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra were also predicted from the calculated intensities. 1H and 13C NMR spectra were recorded and 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-Visible spectrum of the compound was recorded and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman activities chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule. The influences of chlorine atom and the amino group on the skeletal modes and on the proton chemical shifts have been investigated. © 2011 Elsevier B.V. All rights reserved. Source


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Balamourougane P.S.,University | Mythili C.V.,Rani Anna Government College for Women | Mohan S.,Hawasa University | Nandhakumar V.,AVVM Sri Pushpam College
Journal of Molecular Structure | Year: 2011

The FT-IR (4000-400 cm -1) and FT-Raman (4000-100 cm -1) spectral measurements of 2-amino-6-fluorobenzothiazole (2A6FBT) and complete assignments of the observed spectra have been proposed. Ab initio and DFT calculations have been performed and the structural parameters of the compound are determined from the optimised geometry with 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets and giving energies, harmonic vibrational frequencies, depolarisation ratios, IR intensities, Raman activities and atomic displacements. 1H and 13C NMR spectra were recorded and 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-Visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were measured by time-dependent DFT (TD-DFT) approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman activities chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule. The influences of fluoro and amino group on the skeletal modes and on the proton chemical shifts have been investigated. © 2011 Elsevier B.V. All rights reserved. Source

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