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Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Mohan S.,Hawasa University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

The Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of 2,3-hexadiene have been recorded in the regions 3400-400 and 3400-100 cm -1, respectively. A complete assignment and analysis of the fundamental vibrational modes of the molecule were carried out. The observed fundamental modes have been compared with the harmonic vibrational frequencies computed using HF and DFT (B3LYP, B3PW91) methods by employing 6-31G(d,p) and 6-311++G(d,p) basis sets. The scaled vibrational frequencies are found to coincide with the experimentally observed values. Theoretical infrared and Raman spectra at HF and DFT levels have been constructed and compared with the experimental spectra. A comparative study of computed optimised geometrical parameters, infrared and Raman intensities, thermodynamic values and frequencies obtained by different quantum mechanical methods were presented. Molecular electrostatic potential, total density distribution and frontier orbital energy levels are constructed to understand the electronic properties. The most stable geometry of the compound under investigation has been determined from the potential energy surface scan. © 2011 Elsevier B.V. All Rights Reserved.


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Jose S.P.,Madurai Kamaraj University | Mohan S.,Hawasa University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

The energy, geometrical parameters and vibrational wavenumbers of crotonaldehyde were calculated by using ab initio and B3LYP with 6-31G(d,p) and 6-311G(d,p) basis sets. The FT-IR and FT-Raman spectra for liquid state crotonaldehyde have been recorded in the region 3400-400 cm -1 and 3400-100 cm -1, respectively and compared with the theoretical spectrographs constructed from the scaled harmonic vibrational frequencies calculated at HF and DFT levels. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. Detailed interpretations on vibrational modes have been made on the observed and theoretical spectra and PED for each mode was also reported more precisely. HOMO and LUMO energy levels are constructed and the corresponding theoretical frontier energy gaps are calculated to realise the charge transfer occurring in the molecule. The thermodynamic properties of the title compound have been calculated at different temperatures and the results reveals the standard heat capacities (C 0 p), standard entropies (S 0) and standard enthalpy changes (ΔH 0) increases with rise in temperature. © 2011 Elsevier B.V.


Petrus A.J.A.,Kanchi Mamunivar Center for Post Graduate Studies | Bhuvaneshwari N.,Dr Pauls Engineering College
Asian Journal of Chemistry | Year: 2012

Mukia maderaspatana (Linn.) M. Roemer, (Family: Cucurbitaceae) is an indigenous leafy vegetable, reported to offer protection against a number of oxidative stress-mediated ailments. Earlier studies have brought to light the total phenolic contents, reactive species (ROS/RNS) scavenging and metal chelating capacities of the leaf extract. 2,2'-Azino-bis(3-ethylbenzothiazoline- 6-sulphonate (ABTS •+), super oxide (O 2 •-) and NO scavenging capacities, ferric-reducing antioxidant power (FRAP) and ferrous chelating capacities of six C-glucoflavones, isolated and characterized from the edible leaves have been evaluated. 6-C-β-D-glucopyranosylluteolin (4) and 8-C-β-Dglucopyranosylluteolin (6) exhibited maximum ROS/RNS scavenging capacities, while the predominant flavone of the leaf, 7-O-β-Dglucopyranosyl- 6-C-β-D- glucopyranosylapigenin (2) fared weakly. 6-C-β-D-glucopyranosylapigenin (3) was found to be a better scavenger of ABTS ·+ whereas 8-C-β-D-glucopyranosylapigenin (5) scavenged O 2 •- better and 7-O-β-D-glucopyranosyl-6-C-β- Dglucopyranosylluteolin (1) scavenged NO better, in addition to possessing a good ferric-reducing antioxidant power. The ferrous chelating capacities were in the order 1 > 6 > 4 > 2 > 5 > 3, depending upon the metal-binding motifs of their molecular structures. 1, 4 and 6 were found to be only 10 % less potent to chelate Fe(II) compared to deferoxamine, the hydroxamic siderophore, widely employed in the treatment of patients constantly submitted to blood transfusion. The potential ROS/RNS scavenging and metal chelating antioxidant capacities of the C-glucoflavones may contribute considerably to the total antioxidant capacity as well as to the reported protective properties of this functional leafy vegetable.


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Kalaivani M.,Kanchi Mamunivar Center for Post Graduate Studies | Senthilkumari S.,Kanchi Mamunivar Center for Post Graduate Studies | Mohan S.,University of the Humanities
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The vibrational assignment and analysis of the fundamental modes of the compounds acetoacetanilide (AAA), 2-chloroacetoacetanilide (2CAAA) and 2-methylacetoacetanilide (2MAAA) have been performed. Density functional theory studies have been carried out with B3LYP method utilising 6-311++G ** and cc-pVTZ basis sets to determine structural, thermodynamic and vibrational characteristics of the compounds and also to understand the influence of chloro and methyl groups on the characteristic frequencies of amide (-CONH-) group. intramolecular hydrogen bond exists in acetoacetanilide and o-substituted acetoacetanilide molecules and the N⋯O distance is found to be around 2.7 Å. The 1H and 13C nuclear magnetic resonance chemical shifts of the molecules were determined and the same have been calculated using the gauge independent atomic orbital (GiAO) method. The energies of the frontier molecular orbitals have been determined. in AAA, 2CAAA and 2MAAA molecules, the nN → pπ* co Interaction between the nitrogen lone pair and the amide C=O antibonding orbital gives strong stabilization of 64.75, 62.84 and 64.18 kJ mol 1, respectively. The blue shift in amide-ii band of 2MAAA is observed by 45-50 cm1 than that of AAA. The steric effect of ortho methyl group significantly operating on the N-H bond properties. The amide-iii, the C-N stretching mode of methyl and chloro substituted aceto-acetanilide compounds are not affected by the substitution while the amide-V band, the N-H out of plane bending mode of 2-chloroacetoacetanilide compound is shifted to a higher frequency than that of AAA. The substituent chlorine plays significantly and the blue shift in o-substituted compounds than the parent in the amide-V vibration is observed. The amide-Vi, C=O out of plane bending modes of 2MAAA and 2CAAA are significantly raised than that of AAA. A blue shift of amide-Vi, C=O out of plane bending modes of 2MAAA and 2CAAA than AAA is observed. © 2013 Elsevier B.V. All rights reserved.


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Raj A.,Kanchi Mamunivar Center for Post Graduate Studies | Ravindran P.,Mahatma Gandhi Government Arts College | Mohan S.,University of the Humanities
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2014

The vibrational fundamental modes of 2-(methylthio)benzimidazole (2MTBI) have been analysed by combining FTIR, FT-Raman and quantum chemical calculations. The structural parameters of the compound are determined from the optimised geometry by B3LYP with 6-31Gâ̂- â̂ -, 6-311++Gâ̂ - â̂ - and cc-pVTZ basis sets and giving energies, harmonic vibrational frequencies, depolarisation ratios, IR intensities and Raman activities. 1H and 13C NMR spectra have been analysed and 1H and 13C nuclear magnetic resonance chemical shifts are calculated using the gauge independent atomic orbital (GIAO) method. The structure-activity relationship of the compound is also investigated by conceptual DFT methods. The chemical reactivity and site selectivity of the molecule has been determined with the help of global and local reactivity descriptors. © 2013 Elsevier B.V. All rights reserved.


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Rani T.,PRIST University | Mohan S.,Hawasa University
Journal of Molecular Structure | Year: 2011

The FTIR and FT-Raman spectra of 2-(trifluoromethyl)aniline (2TFMA) and 3-(trifluoromethyl)aniline (3TFMA) have been recorded in the range 4000-400 and 4000-100 cm-1, respectively. The experimental vibrational frequencies were assigned and interpreted satisfactorily. The interpretation relies on the theoretical calculations at B3LYP and B3PW91 gradient methods using the standard 6-31G** and higher 6-311++G** basis sets. The frequency calculations were done in ab initio HF method with only 6-311++G** basis set. An extensive study on the vibrational, structural, thermodynamic characteristics as well as the electronic properties of 2TFMA and 3TFMA were carried out using ab initio and DFT methods. In this kind of systems, the position of the substituent group in the benzene ring as well as its electron donor-acceptor capabilities play a very important role on the molecular structural and electronic properties. The influences of the substituents on the structural and electronic properties have been analysed. The intramolecular hydrogen bonds responsible for many features of 2TFMA were analysed. The 1H and 13C FTNMR spectra have been recorded and 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were also 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 performed by time-dependent DFT (TD-DFT) approach. © 2011 Elsevier B.V. All rights reserved.


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Kalaivani M.,Kanchi Mamunivar Center for Post Graduate Studies | Marchewka M.K.,Institute of Low Temperature And Structure Research | Mohan S.,Hawassa University
Journal of Molecular Structure | Year: 2013

The crystal structure investigations of melamine with phosphorous acid, namely melaminium dihydrogenphosphite monohydrate (C3N 6H7·H2PO3·H 2O) have been investigated by means of single crystal X-ray diffraction method. The title compound crystallizes in monoclinic crystal system, and the space group is P21/c with a = 10.069 Å, b = 21.592 Å, c = 12.409 Å and Z = 12. The vibrational assignments and analysis of melaminium dihydrogen phosphite monohydrate have also been performed by FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical simulations were performed with DFT (B3LYP) method using 6-31G **, cc-pVTZ, and 6-311++G** basis sets to determine the energy, structural, thermodynamic parameters and vibrational frequencies of melaminium dihydrogen phosphite monohydrate. The hydrogen atom from phosphorous acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak OH···O and NH···O hydrogen bonds shows notable vibrational effects. © 2013 Elsevier B.V. All rights reserved.


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Ravindran P.,PRIST University | Rani T.,PRIST University | Mohan S.,Hawasa University
Journal of Molecular Structure | Year: 2011

The Fourier transform infrared (FTIR) and FT-Raman spectra of 8-chloroquinoline (8CQ) and 8-nitroquinoline (8NQ) have been recorded in the range 4000-400 and 4000-100 cm-1, respectively. The complete vibrational assignment and analysis of the fundamental modes of the compounds were carried out using the observed FTIR and FT-Raman data. Ab initio and DFT calculations have been performed and the structural parameters of the compounds are determined from the optimized geometries with 6-31G**, 6-311++G** and cc-pVTZ basis sets. 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 performed 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 experimental data of the molecule. The influence of chloro and nitro groups on the skeletal modes and on the proton chemical shifts have been investigated. © 2010 Elsevier B.V. All rights reserved.


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Raj A.,Kanchi Mamunivar Center for Post Graduate Studies | Subramanian S.,Pondicherry Engineering College | Mohan S.,Hawasa University Main Campus
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The FTIR and FT-Raman spectra of 1,2,4-benzenetricarboxylic-1,2-anhydride (BTCA) have been recorded in the range 4000-400 and 4000-100 cm-1, respectively. The complete vibrational assignments and analysis of BTCA have been performed. More support on the experimental findings was added from the quantum chemical studies performed with DFT (B3LYP, MP2, B3PW91) method using 6-311++G, 6-31G and cc-pVTZ basis sets. The structural parameters, energies, thermodynamic parameters, vibrational frequencies and the NBO charges of BTCA were determined by the DFT method. The 1H and 13C isotropic chemical shifts (δ ppm) of BTCA with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. The delocalization energies of different types of interactions were determined. © 2013 Elsevier B.V. All rights reserved.


Layavarjitha S.,Kanchi Mamunivar Center For Post Graduate Studies | Kadamban D.,Kanchi Mamunivar Center For Post Graduate Studies
International Journal of Pharma and Bio Sciences | Year: 2014

The antioxidant activity of leaf, unripe and ripe fruits of Lantana camara L. were determined using H2O2 radical scavenging activity and Ferric Reducing antioxidant power (FRAP) assay. Ethanol, methanol, ethyl acetate and water extracts prepared from dry leaf powder and fresh fruits of both unripe and ripe fruits were used to find out the antioxidant activity. All the four extracts of leaf, unripe and ripe fruits showed considerable antioxidant effect. Water extract of powdered leaf showed a maximum activity of 94.81% where as aqueous extract of unripe fruit showed the least of 0.05% in FRAP activity . In H2O2 radical scavenging activity water extract of unripe showed the highest activity of 14.53% and methanol, ethyl acetate and water extracts of leaf powder showed the least activity of 3.05%. As the leaf, unripe and ripe fruits of Lantana camara have antioxidant potential they can be studied from pharmaceutical and nutraceutical aspects.

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