Indore, India

Devi Ahilya University
Indore, India

Devi Ahilya University also called Indore University, is a university operated by the state of Madhya Pradesh at Indore, India, named after Devi Ahilya Bai Holkar belonging to the Holkar dynasty of the Marathas. Wikipedia.

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Density Functional Theory calculations have been performed for the σ-hydroboryl complexes of iron, ruthenium and osmium [(H) 2Cl(PMe 3) 2M(σ-H-BR)] (M = Fe, Ru, Os; R = OMe, NMe 2, Ph) at the BP86/TZ2P/ZORA level of theory in order to understand the interactions between metal and HBR ligands. The calculated geometries of the complexes [(H) 2Cl(PMe 3) 2Ru(HBNMe 2)], [(H) 2Cl(PMe 3) 2Os(HBR)] (R = OMe, NMe 2) are in excellent agreement with structurally characterized complexes [(H) 2Cl(P iPr 3) 2Os(σ-H-BNMe 2)], [(H) 2Cl(P iPr 3) 2Os{σ-H-BOCH 2CH 2OB(O 2CH 2CH 2)}] and [(H) 2Cl(P iPr 3) 2Os(σ-H- BNMe 2)]. The longer calculated M-B bond distance in complex [(H) 2Cl(PMe 3) 2M(σ-H-BNMe 2)] are due to greater B-N π bonding and as a result, a weaker M-B π-back-bonding. The B-H2 bond distances reveal that (i) iron complexes contain bis(σ-borane) ligand, (ii) ruthenium complexes contain (σ-H-BR) ligands with a stretched B-H2 bond, and (iii) osmium complexes contain hydride (H2) and (σ-H-BR) ligands. The H-BR ligands in osmium complexes are a better trans-directing ligand than the Cl ligand. Values of interaction energy, electrostatic interaction, orbital interaction, and bond dissociation energy for interactions between ionic fragments are very large and may not be consistent with M-(σ-H-BR) bonding. The EDA as well as NBO and AIM analysis suggest that the best bonding model for the M-σ-H-BR interactions in the complexes [(H) 2Cl(PMe 3) 2M(σ-H-BR)] is the interaction between neutral fragments [(H) 2Cl(PMe 3) 2M] and [σ-H-BR]. This becomes evident from the calculated values for the orbital interactions. The electron configuration of the fragments which is shown for C in Fig. 1 experiences the smallest change upon the M-σ-H-BR bond formation. Since model C also requires the least amount of electronic excitation and geometry changes of all models given by the ΔE prep values, it is clearly the most appropriate choice of interacting fragments. The π-bonding contribution is 14-22% of the total orbital contribution. © The Royal Society of Chemistry 2012.

Singh S.P.,Devi Ahilya University | Singh D.,Devi Ahilya University
Renewable and Sustainable Energy Reviews | Year: 2010

The world is confronted with the twin crises of fossil fuel depletion and environmental degradation. The indiscriminate extraction and consumption of fossil fuels have led to a reduction in petroleum reserves. Petroleum based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain region of the world. Therefore, those countries not having these resources are facing a foreign exchange crisis, mainly due to the import of crude petroleum oil. Hence it is necessary to look for alternative fuels, which can be produced from materials available within the country. Although vegetative oils can be fuel for diesel engines, but their high viscosities, low volatilities and poor cold flow properties have led to the investigation of its various derivatives. Among the different possible sources, fatty acid methyl esters, known as Biodiesel fuel derived from triglycerides (vegetable oil and animal fates) by transesterification with methanol, present the promising alternative substitute to diesel fuels and have received the most attention now a day. The main advantages of using Biodiesel are its renewability, better quality exhaust gas emission, its biodegradability and the organic carbon present in it is photosynthetic in origin. It does not contribute to a rise in the level of carbon dioxide in the atmosphere and consequently to the green house effect. This paper reviews the source of production and characterization of vegetable oils and their methyl ester as the substitute of the petroleum fuel and future possibilities of Biodiesel production. © 2009 Elsevier Ltd. All rights reserved.

Singh S.P.,Devi Ahilya University | Singh P.,Devi Ahilya University
Renewable and Sustainable Energy Reviews | Year: 2014

Natural changes in climate due to internal as well as external factors, like anthropogenic emission, fossil fuel combustion, transportation and heating which cause CO2 emissions is one of the major issues which causes global warming (increasing concentrations of greenhouse gases). The production of algae is identified as one of the solutions of carbon sequestration along with production of renewable fuel solving the problem of food crisis to a certain extent. This review paper summarizes how CO2 levels affected micro algal species. Several species of algae as Scenedesmus obliquus, Botryococcus braunii, Chlorella vulgaris, Nannochloropsis oculata have been reported to accumulate high concentration of lipid. These species are suitable for biofuel production as well as Carbon fixation. © 2014 Published by Elsevier Ltd.

Geometry, electronic structure, and bonding analysis of the terminal neutral bis(borylene) complexes of cobalt, rhodium, and iridium [(η 5-C 5H 5)M(BNX 2) 2] (M = Co, Rh, Ir; X = Me, SiH 3, SiMe 3) were investigated at the DFT/BP86/TZ2P/ ZORA level of theory. The calculated geometry of iridium complex [(η 5-C 5H 5)Ir{BN- (SiMe 3) 2} 2] is in excellent agreement with structurally characterized iridium complex [(η 5-C 5Me 5)Ir{BN(SiMe 3) 2} 2]. Pauling, Mayer, and Nalewajski-Mrozek bond multiplicities of the optimized structures of bis(borylene) complexes show that the M?B bonds in these complexes are nearly M=B double bonds. On substitution of the BNX 2 ligand by the more π-acidic CO ligand, the calculated M?B bond distances increase, while substitution of the BNX 2 ligand by the less π- acidic PMe 3 ligand results in a decrease of the calculated M?B bond distances. The acute B?M?B bond angle and short B?B bond distance, in particular in cobalt bis(borylene) complexes, reveal the presence of a MB 2 interaction consistent with some degree of weak B?B bonding. The π-bonding contribution is, in all complexes, smaller (28.4?32.6% of total orbital contributions) than the σ-bonding contribution. The BNX 2 ligands are relatively poor π acceptors compared with the CO ligand, but better π acceptors than the PMe3 ligand. The contribution of M ? BNX 2 δEσ is clearly the dominant term of the orbital interaction. The σ-donor ability of borylene ligands BNX 2 is greater in bis(borylene) complexes [(η 5-C 5H 5)M(BNX 2) 2] than in carbonyl borylene complexes [(η 5-C 5H 5)(CO)M(BNX 2)] and phosphine borylene complexes [(η 5-C 5H 5)(PM 3)M(BNX 2) 2]. The absolute value of various energy terms for the M=B bond decreases upon going from X = Me to SiH 3 and SiMe 3. © 2011 American Chemical Society.

A fifty-four compound series of 5-lipoxygenase and cyclooxygenase inhibitory activity of substituted 3,4-dihydroxychalcones was subjected to the development of a robust quantitative structure-activity relationship (QSAR) and pharmacophore model and the investigation of structure-activity relationship analysis using Molecular Design Suite software version 3.5.The requirements for the 5-lipoxygenase and cyclooxygenase activity are explored with 2D, group based and k-Nearest Neighbor studies. Simulated annealing is applied as variable selection methods for an effective comparison and model development. Several statistical expressionswere developed using partial least square (PLS) analysis. The best QSAR models were further validated by leave-one-out method of cross-validation. The statistically significant best 2D-QSAR model was selected, having correlation coefficient r2 = 0.9338, and cross-validated squared correlation coefficient q2 = 0.7832 with external predictive ability of pred-r2 = 0.8169 was developed by simulated annealing PLS with the descriptors like Average -ve potential, SsCH3E-index, SsClE-index, SsOH count, and HUMO Energy. Group based QSAR model indicates that molar refractivity and methoxy, ethoxy, carboxylic groups in R1 positions can enhance activity. The obtained 3D-QSAR (k-Nearest Neighbor) model using simulated annealing as a variable selection method has an excellent correlation coefficient value (r2 = 0.8537) along with good statistical significance as shown by high Fisher's ratio (F = 73.86). The model also exhibits good predictive power confirmed by the high value of cross-validated correlation coefficient (q2 = 0.7841). The k-Nearest Neighbor contour maps suggest some important structural features like electronegative substituents which are essential for the activity exhibited by these compounds, and inclusion of electron-donating substituents will enhance the 5-lipoxygenase and cyclooxygenase inhibition activity. The pharmacophore analysis of the molecules demonstrated that the aromatic/aliphatic and hydrogen bond donor features are important pharmacophore contours favorable for these activities. The information rendered by 2D-QSAR, group based and 3D-QSAR models may lead to a better understanding of structural requirements of chalcone derivatives and also aid in designing novel potent 5-lipoxygenase and cyclooxygenase molecules. © Springer Science+Business Media 2013.

Geometry and bonding energy analysis of Fe-E bonds in the ferrio-ylenes [(η5-C5H5)(L)2Fe(ER)] (L = CO, PMe3; E = Si, Ge, Sn, Pb; R = Ph, Me) were investigated at the DFT, DFT-D3 and DFT-D3(BJ) methods using density functionals (BP86, PW91, PBE, revPBE and TPSS). The TPSS functional yields better geometry and calculated geometrical parameters for the model ferrio-ylenes are in agreement with the experimental values for ferrio-ylenes. The Fe-E bonds in these complexes are essentially Fe-E single bonds. In all studied complexes, the π-bonding contribution to the total Fe-ER bond is significantly smaller than that of the σ-bonding. The electrostatic interactions ΔEelstat are larger than the covalent bonding ΔEorb terms in all ferrio-ylene complexes. The DFT-D3 method provide quite accurate estimate of the dispersion energy for the studied complexes. The contribution of dispersion interactions is large in computing accurate bond dissociation energies between the interacting metal fragments. The Fe-E bond dissociation energies (BDEs) with shared electron bonding follow the order revPBE < BP86 < TPSS < PBE < PW91. Significant finding of the present study is that the dispersion interactions are almost same for both the bonding models (shared electron and donor-acceptor models). The dispersion interactions are largest for complexes [(η5-C5H5)(PMe3) 2Fe(EPh)] and smallest for [(η5-C5H 5)(CO)2Fe(EMe)]. The strengths of dispersion interactions are sensitive to the (i) separation between the interacting fragments, (ii) size of ancillary ligands and (iii) substituent of the ligand fragment. The DFT-D3 dispersion corrections to the BDEs are smaller than the corresponding DFT-D3(BJ) dispersion corrections. © 2014 Elsevier B.V. All rights reserved.

New, simple and cost-effective UV-spectrophotometric, RP-HPLC and densitometric methods were developed for the estimation of pseudoephidrine sulphate and desloratidine in bulk and pharmaceutical formulations. In this study, a first-derivative spectroscopic method was used for simultaneous determination of pseudoephidrine sulphate and desloratidine using the zero-crossing technique. The measurements were carried out at wavelengths of 265.1 and 279.5 nm for pseudoephidrine sulphate and desloratidine, respectively. The second method based on reverse phase-high performance liquid chromatography separation was performed by using C18 column Phenomenex Luna C18 (5 μm×25 cm×4.6 mm i.d.) coupled with a guard column of same material, in mobile phase acetonitrile:methanol:triethylamine (20:5:75). The pH of mobile phase was adjusted to 4.8 ± 0.1 with 50% orthophosphoric acid. The flow rate was 1.0 ml min-1 and the separated drugs were detected using an UV detector at the wavelength of 280 nm. The method employed RP-TLC aluminium plates pre-coated with silica gel 60 RP-18 F254 S as the stationary phase. The mobile phase consisted of glacial acetic acid: methanol (90:10 v/v). The system was found to give compact spot for pseudoephidrine sulphate (Rf value of 0.26 ± 0.08) and Rf value of 0.48 ± 0.16 for desloratidine. Densitometric detection was carried out at λ = 296 nm. For preparation of a calibration plot, 200-600 and 100-600 ng/spot standard solutions of pseudoephidrine sulphate and desloratidine were applied, respectively. This method is simple, precise, and sensitive and applicable for the simultaneous determination of pseudoephidrine sulphate and desloratidine in formulation.

Simple extractive spectrophotometric and HPLC methods are described for the determination of lumefantrine in pure form and in pharmaceutical formulations. These methods are based on the formation of ion association complexes of the lumefantrine with basic dyes safranin O and methylene blue in basic buffer of pH 8. The second method described liquid chromatographic procedure that uses micellar mobile phase containing only Tween-20 and n-butanol, is reported for the determination of method for estimation of lumefantrine dosage form. HPLC separation was performed on a Licrosphere C18 column (250 × 4.6 mm) using Tween-20 and n-butanol phosphate buffer, pH 5.1 (60:20:20 v/v) at a flow rate of 1.0 ml/min at 25oC. The % RSD for precision and accuracy of the method was found to be less than 2%. The method was validated as per the ICH guidelines. The method was successfully applied for routine analysis of lumefantrine in bulk samples and its formulations.

The present study aimed at the development and validation of a first-derivative ultraviolet (UV) spectrophotometric method for the estimation of pioglitazone hydrochloride in bulk and pharmaceutical dosage form which is based on the measurement of absorption maxima at 385 nm. The linearity was observed in the range from 5 to 30 μg/ml. A simple, selective, linear, precise and accurate RP-HPLC method was developed and validated for rapid assay of pioglitazone hydrochloride in tablet dosage form. Isocratic elution at a flow rate of 1.0 ml/min was employed on a symmetry 25 cm × 4.6 mm i.d., 5-μm particle, Phenomenex Luna C18 column at ambient temperature. The mobile phase consisted of acetonitrile:methanol 80:20 (v/v). The UV detection wavelength was 385 nm and 20-μl sample was injected. The retention time for pioglitazone hydrochloride was 3.685 min. High performance thin layer chromatographic method has been developed and validated for the estimation of pioglitazone hydrochloride in tablet dosage forms. The method employed TLC aluminium plates pre-coated with silica gel 60 F 254 as a stationary phase. The mobile phase used was a mixture of glacial acetic acid: methanol: carbon tetrachloride (4:2:4 v/v/v). The detection of spot was carried out at 289 nm. The calibration curve was found to be linear between 100 and 700 ng ml-1 with regression coefficient of 0.9998.

This paper describes validated derivative spectrophotometry (D2) method for simultaneous estimation of tenofovir disoproxil fumerate (TF) and emtricitabine (EM) in formulation. Second derivative spectrophotometry method, applying the peak zero method, was developed for the determination of tenofovir disoproxil fumerate and emtricitabine in their combined tablet formulations without prior separation. Quantitative determination of the drugs was performed at 342.8 and 298.3 nm for tenofovir disoproxil fumerate and emtricitabine, respectively. Second RP-HPLC method for simultaneous analysis of tenofovir disoproxil fumerate and emtricitabine has been developed and validated. The quantification was carried out using a thermo-hypersil ODS-C18 (250 mm × 4.6 mm, 5.0 μ) column and mobile phase comprised of acetonitrile: 0.05M potassium dihydrogen phosphate with triethylamine (65: 35 v/v). Total run time was less than 8 min; retention time for tenofovir disoproxil fumerate and emtricitabine was 6.841 and 7.415 min, respectively. TLC-densitometry method has been developed and validated for the determination of tenofovir disoproxil fumerate and emtricitabine in dosage form. The stationary phase used was pre-coated silica gel 60F254. The mobile phase used was a mixture of chloroform:carbon tetrachloride:acetone (6:4:2 v/v/v). The detection of spot was carried out at 246.4 nm. The method was validated in terms of linearity, accuracy, precision and specificity.

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