Presence Of Non-polar Solvents Research Articles

Cytotoxic activity and DNA fragmentation study of nano structured assemblies of copper sulfide nanoparticles using single route molecular precursor source of copper

In this paper, we have reported an easy, template free and squashy solution chemistry path was applied to synthesize variegated nanostructured congregation assemblies of copper nanoparticles at room temperature using hydrazinecarbothioamide coordinated Cu(II) complex through a single route molecular precursor source. The parent compounds were heated under microwave irradiation to obtain diversified CuS nanostructures in the shapes of spheres and nanotubes were found to be assemblies of either nanoplates or nanoparticles. The formation of nanostructured CuS nano particles was detailed studied by differing the synthetic conditions such as reaction time, temperature, parent compounds ratio, and the presence of counter ions. The presence of NO3 - and SO4 2- ions as counter ions were found to be suitable for the formation of nanotubes whereas the presence of Clions initiate the formation of spherical nano assemblies of CuS nano material is obtained. The synthesized samples were characterized using various structural, morphological and optical characterization techniques like elemental analysis, FT-IR, UV-Vis, and thermogravimetric analysis/differential thermogravimetric (TGA/DG). Important changes were observed in the FT-IR spectra of the copper complex compared to the FT-IR spectrum of ligand. X-ray diffraction studies confirms the formation of hexagonal crystalline phase of CuS nano particles: Transmission electron microscopy exhibit nanotube like structures with an average particle size of 78nm. Strong UV absorption band at 425nm confirms the formation of good quality CuS nano particles. The microwave irradiation of parent compounds in the presence of nonpolar solvents like DMF, DMSO environment played a significant role in decreasing the reaction time, decreases the possibility of side reactions and proceeds the reaction in the formation of good quality nanoparticles. The SEM analysis of CuS nano particles confirms the agglomerated grain like surface morphology of nanoparticles. All compounds showed the various pharmacological activities like antioxidant, antibacterial activities due to the presence of strong electron withdrawing and electron releasing functional groups are present in molecular precursors. The microwave synthesis of CuS nanostructured assemblies in nonpolar solvent in a proper stoichiometric ratio is an excellent method for preparing highly efficient bio active agents like antibacterial & antioxidant agents which can be considered as a good drug candidate for medicinal chemists in future.

Supramolecular dimers drive the reaction between CO2 and alkanolamines towards carbonate formation

In this work we revisited the mechanisms for CO2 absorption in pure alkanolamines (monoethanolamine, diethanolamine, 2 −amino−2 −methyl−1 −propanol, and ethylenediamine) and in their 30% (v/v) aqueous solution, leading to the corresponding carbonate or carbamate. Fourier-transform infrared and 13C nuclear magnetic resonance spectroscopies strongly suggest that in the aqueous medium the main product is carbamate, whereas in the pure alkanolamines or in an acetonitrile solution carbonate is formed. Density functional theory simulations indicate that when alkanolamine monomers are used, carbamic acid is the most stable product. On the contrary, alkanolamine dimers led mainly to a zwitterionic carbonate. The effect of the solvent was also studied showing that in aqueous medium alkanolamines react as monomers with CO2 to produce carbamates. In pure alkanolamines or in the presence of nonpolar solvents, the main species are the alkanolamine supramolecular dimers, which react with CO2 to form carbonates.

Characterization and Application of Yarrowia lipolytica Lipase Obtained by Solid-State Fermentation in the Synthesis of Different Esters Used in the Food Industry

Yarrowia lipolytica lipase obtained by solid-state fermentation was characterized and applied in the synthesis of esters with commercial value in the food industry. The effect of different conditions on the hydrolysis activity of this biocatalyst was evaluated in the presence of metal ions, solvents, detergents, several pH and temperature parameters, and different substrates. Storage stability was also studied. The solid biocatalyst produced in soybean meal was used in synthesis reactions aiming to produce short-, medium-, and long-chain esters. Results showed that the best fermentation condition to produce the biocatalyst was using soybean oil (3% w/w), moisture content (55% w/v), and inoculum of 2.1mgdry biomass/gsoybean meal at 28°C for 14h. High substrate conversion for ethyl octanoate, cetyl stearate, and stearyl palmitate synthesis was achieved in the presence of non-polar solvents in less than 6h using a substrate molar ratio of 1:1 at 38°C with 10-15% (w/v) of biocatalyst. This work showed the high potential of Y. lipolytica lipase to be used in the synthesis of different esters. Also, that it can be considered an attractive and economical process alternative to obtain high-added value products.

Influence of different solvents on portrayal and photocatalytic activity of tin-doped zinc oxide nanoparticles

Tin doped zinc oxide (Sn-ZnO) nanoparticles were synthesized by precipitation-deposition method in different polar and non-polar solvents (2-propanol, acetonitrile, n-hexane and 3-Methyl-1-butanol). As-synthesized Sn-ZnO nanoparticles (NPs) were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Raman spectroscopy and photoluminescence (PL) techniques. Solvents showed variable effect on Sn-ZnO NPs physico-chemical characteristics. Sn-doped ZnO NPs showed smaller particle size in n-hexane versus 2-proponol and 3-methyl-l-butanol (isoamyl alcohol). Moreover, the doping of Sn was more favorable in the presence of non-polar solvent. As-synthesized Sn-ZnO NPs also showed a significant photocatalytic activity (PCA), which was more promising for Sn-ZnO versus ZnO. Results revealed that solvents (polar and non-polar) have variable effect for the doping of Sn with ZnO and Sn-ZnO NPs proved to be highly active photocatalyst.

Substrate kinetics of thiol activated hyperthermostable alkaline lipase of Bacillus sonorensis 4R and its application in bio-detergent formulation

Abstract The substrate kinetics of a hyperthermostable alkaline lipase from Bacillus sonorensis 4R (BSL) was studied and the enzyme was used to develop presoak formulation for removing oil stains at 37 °C and 80 °C. The purified BSL was thiol activated with 112.49% and 37.49% enhancement in presence of 5 mM thiourea and dithiothreitol (DTT) respectively. BSL displayed higher specificity for mustard oil and cotton seed oil cake than olive oil as a standard substrate. The maximal velocity (Vmax) and Michaelis constant (Km) values determined in presence of olive oil, mustard oil and cotton seed oil cake were 5.0, 7.14, 5.55 µM and 3.22, 2.5 and 2.22 µM/ml/min respectively. Effect of phenylmethylsulfonyl flouride (PMSF) and N-Bromosuccinimide (NBS) on BSL catalyzed hydrolysis of olive oil, mustard oil and cotton seed oil cake were studied in terms of changes in Vmax, Km, catalytic efficiency and substrate utilization capacity. BSL catalyzed improved hydrolysis of cotton seed oil cake in presence of thiourea and retained 100% stability in presence of non-polar solvents, surfactants and detergents. BSL (15 Eu/100 ml) was effective in removal of olive oil stains studied at three aging periods (0, 7 and 15 d) and two washing temperatures (37 °C and 80 °C). The BSL action during wash performance studies for all aging periods was demonstrated clearly by quantitated fatty acid release. BSL exhibited excellent olive oil removal capacity than buffer (pH 9.0) and Tide (1%). The combination of BSL and Tide proved best formulation for stain removal of olive oil soiled fabrics.

Structural elucidation and molecular characterization of Marinobacter sp. α-amylase

ABSTRACTHalophiles have been perceived as potential source of novel enzymes in recent years. The interest emanates from their ability to catalyze efficiently under high salt and organic solvents. Marinobacter sp. EMB8 α-amylase was found to be active and stable in salt and organic solvents. A study was carried out using circular dichroism (CD), fluorescence spectroscopy, and bioinformatics analysis of similar protein sequence to ascertain molecular basis of salt and solvent adaptability of α-amylase. Structural changes recorded in the presence of varying amounts of NaCl exhibited an increase in negative ellipticity as a function of salt, confirming that salt stabilizes the protein and increases the secondary structure, making it catalytically functional. The data of intrinsic and extrinsic fluorescence (using 1-anilinonaphthalene 8-sulfonate [ANS] as probe) further confirmed the role of salt. The α-amylase was active in the presence of nonpolar solvents, namely, hexane and decane, but inactivated by ethanol. The decrease in the activity was correlated with the loss of tertiary structure in the presence of ethanol. Guanidine hydrochloride and pH denaturation indicated the molten globule state at pH 4.0. Partial N-terminal amino acid sequence of the purified α-amylase revealed the relatedness to Pseudoalteromonas sp. α-amylase. “FVHLFEW” was found as the N-terminal signature sequence. Bioinformatics analysis was done using M. algicola α-amylase protein having the same N-terminal signature sequence. The three-dimensional structure of Marinobacter α-amylase was deduced using the I-TASSER server, which reflected the enrichment of acidic amino acids on the surface, imparting the stability in the presence of salt. Our study clearly indicate that salt is necessary for maintaining the secondary and tertiary structure of halophilic protein, which is a necessary prerequisite for catalysis.

ChemInform Abstract: Iridium(I) Complexes with Anionic N‐Heterocyclic Carbene Ligands as Catalysts for the Hydrogenation of Alkenes in Nonpolar Media.

A series of lithium complexes of anionic N-heterocyclic carbenes that contain a weakly coordinating borate moiety (WCA-NHC) was prepared in one step from free N-heterocyclic carbenes by deprotonation with n-butyl lithium followed by borane addition. The reaction of the resulting lithium-carbene adducts with [M(COD)Cl]2 (M = Rh, Ir; COD = 1,5-cyclooctadiene) afforded zwitterionic rhodium(I) and iridium(I) complexes of the type [(WCA-NHC)M(COD)], in which the metal atoms exhibit an intramolecular interaction with the N-aryl groups of the carbene ligands. For M = Rh, the neutral complex [(WCA-NHC)Rh(CO)2] and the ate complex (NEt4)[(WCA-NHC)Rh(CO)2Cl] were prepared, with the latter allowing an assessment of the donor ability of the ligand by IR spectroscopy. The zwitterionic iridium–COD complexes were tested as catalysts for the homogeneous hydrogenation of alkenes, which can be performed in the presence of nonpolar solvents or in the neat alkene substrate. Thereby, the most active complex showed excellent s...

Iridium(I) Complexes with Anionic N-Heterocyclic Carbene Ligands as Catalysts for the Hydrogenation of Alkenes in Nonpolar Media

A series of lithium complexes of anionic N-heterocyclic carbenes that contain a weakly coordinating borate moiety (WCA-NHC) was prepared in one step from free N-heterocyclic carbenes by deprotonation with n-butyl lithium followed by borane addition. The reaction of the resulting lithium-carbene adducts with [M(COD)Cl]2 (M = Rh, Ir; COD = 1,5-cyclooctadiene) afforded zwitterionic rhodium(I) and iridium(I) complexes of the type [(WCA-NHC)M(COD)], in which the metal atoms exhibit an intramolecular interaction with the N-aryl groups of the carbene ligands. For M = Rh, the neutral complex [(WCA-NHC)Rh(CO)2] and the ate complex (NEt4)[(WCA-NHC)Rh(CO)2Cl] were prepared, with the latter allowing an assessment of the donor ability of the ligand by IR spectroscopy. The zwitterionic iridium-COD complexes were tested as catalysts for the homogeneous hydrogenation of alkenes, which can be performed in the presence of nonpolar solvents or in the neat alkene substrate. Thereby, the most active complex showed excellent stability and activity in hydrogenation of alkenes at low catalyst loadings (down to 10 ppm).

ChemInform Abstract: Improved Method for the Preparation of 1,1‐Dimethyl‐3‐arylureas Using Chlorocarbonylsulfenyl Chloride.

AbstractAll products are purified by recrystallization.

Improved Method for the Preparation of 1,1-Dimethyl-3-arylureas Using Chlorocarbonylsulfenyl Chloride

A convenient procedure for preparing some arylureas having herbicidal properties is reported. The method has two steps: (1) reaction of arylamine with chlorocarbonylsulfenyl chloride in the presence of nonpolar solvent to produce aryl carbonylsulfenyl chloride and (2) reaction with dimethylamine in a two-phase reaction catalysed by phase-transfer catalyst to produce the corresponding aryl ureas.

Validation of a one-step extraction/methylation method for determination of fatty acids and cholesterol in marine tissues

A simple and fast direct extraction/methylation with methanolic hydrogen chloride was validated for determination of fatty acids (FA) in marine tissues. Three parameters: reaction time, temperature and presence of non-polar solvent, were studied by an experimental 2 3 full factorial design. The method was validated for five different types of samples; cod liver (high lipid content >60%, mainly triacylglycerol), cod muscle (low lipid content, ≈1%, mainly phospholipids), cod plasma (lipid content, ≈2%, mainly lipoprotein complex, high water amount), cod testis (lipid content ≈3%, high levels of cholesterol), and herring muscle (lipid content ≈7%). The one-step procedure for extraction/methylation of wet tissues was compared with the traditional procedure of extraction of the lipids by the Folch method (chloroform/methanol, 2:1, v/v), followed by methylation. The two methods gave similar FA profiles. The one-step extraction/methylation procedure gave a higher recovery of the total FA than the traditional procedure. Problems with carry-over peaks of cholesterol from previous samples were avoided by application of extra long GC temperature programs. The cholesterol decomposed to some degree under the preceding methanolysis step, giving several peaks in the chromatograms. The decomposition peaks were identified by mass spectrometry as cholestdienes originating from dehydration of cholesterol, a metylether of cholesterol and a cholesteryl chloride. These cholesterol artefacts can be used for quantitative determination of cholesterol in the samples. Standard samples of cholesterol were determined with high accuracy, ( R 2 > 0.99), and cholesterol in cod plasma was compared with good agreement ( R 2 = 0.97) to an enzymatic method.

The Efficiency of Light-Directed Synthesis of DNA Arrays on Glass Substrates

New methods based on photolithography and surface fluorescence were used to determine photodeprotection rates and stepwise yields for light-directed oligonucleotide synthesis using photolabile 5‘-(((α-methyl-2-nitropiperonyl)oxy)carbonyl)(MeNPOC)-2‘-deoxynucleoside phosphoramidites on planar glass substrates. Under near-UV illumination (primarily 365 nm) from a mercury light source, the rate of photoremoval of the MeNPOC protecting group was found to be independent of both the nucleotide and length of the growing oligomer (t1/2 = 12 s at 27.5 mW/cm2). A moderate dependence on solvent polarity was observed, with photolysis proceeding most rapidly in the presence of nonpolar solvents or in the absence of solvent (e.g., t1/2 = 10−13 s at 27.5 mW/cm2). In solution, the photolysis rate was linearly dependent on light intensity over the range 5−50 mW/cm2. Average stepwise yields for the synthesis of dodecamer oligonucleotides were in the range of 92−94%, using monomers based on N6-(phenoxyacetyl)-2‘-deoxyadenos...

Metal complexes of sulphur ligands. Part III. Reaction of platinum(II)NN-dialkyldithiocarbamates, O-ethyl dithiocarbonate (xanthate), and OO′-diethyl dithiophosphate with tertiary phosphines

Evidence is presented to show that the reaction of all M(S–S)2 compounds [M = Pt, Pd; (S–S)–=–S2CNR2(R = Me, Et), –S2COR (R = Et, PhCH2), –S2P(OEt)2, and –S2PR2(R = Me, Et, Ph)] with tertiary phosphines occurs by stepwise cleavage of metal–sulphur bonds to generate four-co-ordinate compounds of formulae [M(S–S)2PR′3] and [M(S–S)(PR′3)2](S–S) with unidentate/bidentate (III) and ionic/bidentate (IV) co-ordination respectively. All the ionic compounds readily revert to the [M(S–S)2PR′3] complexes in the presence of non-polar solvents via nucleophilic attack by (S–S)– on the metal. In addition, for (S–S)–=–S2COR, –S2P(OEt)2, nucleophilic attack can also occur on a co-ordinated alkoxy group to give the novel compounds [(R′3P)2MS2CO](I) and [(R′3P)2MS2P(O)OEt](II) respectively.For [M(S–S)(PR′3)2](S–S) compounds containing –S2CNR2, the presence of excess PR′3 catalyses the reaction between dithiocarbamate ion and dichloromethane, giving CH2(S2CNR2)2 and [M(S2CNR2)(PR′3)2]Cl, H2O. These conclusions are based on extensive physico-chemical studies and, in particular, the use of variable temperature 1H n.m.r. spectroscopy.

Study of aggregation of the tail sheaths of phage T-2.

The first stages of tail sheath aggregation of phage T2 were investigated by analytical centrifugation, electron microscopy, and turbidity determination. A dependence of the aggregation process on the pH was established with maximum aggregation at pH 3.3. It was shown that aggregation begins with formation of dimers—two sheaths joined end-to-end with a 155 S sedimentation coefficient. The investigation of the dependence of the aggregation on the ionic strength of the solution and the presence of nonpolar solvents, as well as the potentiometric titration, attest the important role of electrostatic interactions in this process.

Ion-exchange resins in non-aqueous solvents—I: Sorption rates of p-nitroaniline and the effects of small amounts of water

The rates of sorption of p-nitroaniline onto three hydrogenform resins in methanol, ethanol, n-propanol, isopropanol, n-butanol, acetonitrile, benzene, acetic acid and dioxan are reported. Two of the resins are typical gel-type, microreticular, sulphonated resins and the third is a new, highly porous and rigid, macroreticular, sulphonated resin, Amberlyst 15. There appears to be a correlation between viscosity or dielectric constant and the time for maximum sorption or maximum distribution coefficient when the alcohols are used, but no correlation for all the solvents is apparent. The macroreticular resin still functions when dry, even in the presence of non-polar solvents, but the microreticular resin does not. Small amounts of water present in the solvent or resin aid the sorption of the amine onto both types of resin. The effect of mesh size and cross-linkage are examined.