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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. Source


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Ravindran P.,University | Rani T.,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. Source


Arjunan V.,Kanchi Mamunivar Center for Post Graduate Studies | Rani T.,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. Source


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. Source


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. Source

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