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51.
FM Machado CP Bergmann EC Lima B Royer FE de Souza IM Jauris T Calvete SB Fagan 《Physical chemistry chemical physics : PCCP》2012,14(31):11139-11153
Multi-walled and single-walled carbon nanotubes were used as nanoadsorbents for the successful removal of Reactive Blue 4 textile dye from aqueous solutions. The adsorbents were characterised by infrared and Raman spectroscopy, N(2) adsorption/desorption isotherms and scanning and transmission electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were studied. In the acidic pH region (pH 2.0), the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium isotherms at 298-323 K was fixed at 4 hours for both adsorbents. The general order kinetic model provided the best fit to the experimental data compared with pseudo-first order and pseudo-second order kinetic adsorption models. For Reactive Blue 4 dye, the equilibrium data (298 to 323 K) were best fitted to the Liu isotherm model. The maximum sorption capacity for adsorption of the dye occurred at 323 K, attaining values of 502.5 and 567.7 mg g(-1) for MWCNT and SWCNT, respectively. Simulated dyehouse effluents were used to check the applicability of the proposed nanoadsorbents for effluent treatment (removal of 99.89% and 99.98%, for MWCNT and SWCNT, respectively). The interaction of Reactive Blue 4 textile dye with single-walled carbon nanotubes (SWCNTs) was investigated using first principles calculations based on density functional theory. Results from ab initio calculations indicated that Reactive Blue 4 textile dye could be adsorbed on SWCNT through an electrostatic interaction; these results are in agreement with the experimental predictions. 相似文献
52.
R. Alan Howie Marcus V. N. de Souza Camilo H. da Silva Lima James L. Wardell Solange M. S. V. Wardell 《Journal of chemical crystallography》2012,42(4):394-400
Abstract
The molecule of (E)-3-(3-MeOC6H4CH=CHCO)-benzotriazole 1-oxide, 2, has a very near planar structure, while the 2-nitrophenyl ring is rotated out of the plane of the remaining atoms in (E)-3-(2-O2NC6H4CH=CHCO)-benzotriazole 1-oxide, 1. The nitrogen oxide bond lengths in 1 and 2 are 1.258 (6) and 1.2683 (15) ?, respectively, and are in the region found for related compounds. There are no strong intermolecular hydrogen-bonds in either compound, instead there are weak C–H···O intermolecular hydrogen-bonds and π···π stacking interactions in 1, and C–H···O, C–H···π, and π···π stacking interactions in 2. Different three-dimensional arrays are generated in each case. Compound 1 crystallises in the orthorhombic space group Pna21, with a = 25.061 (2) ?, b = 3.6997 (2) ?, c = 14.2623 (12) ? and Z = 4. Compound 2 crystallises in the triclinic space group P-1, with a = 5.7297 (3) ?, b = 10.8440 (6) ?, c = 11.4965 (6) ?, α = 89.689 (3)°, β = 76.019 (3)°, γ = 75.047 (3)°, Z = 2. 相似文献53.
The properties of water in the vicinity of surfaces and under confinement have been extensively studied because of the relevance of a quantitative understanding of many processes that not only take place in biological systems, like cells, membranes and microemulsions, but also in many others such as confined water in rocks, ionic channels and interestellar matter. In this work we perform molecular dynamic calculations of the nanoscopic structure of TIP5P model water confined between two hydrophilic surfaces. We calculate the diffusion coefficients and the atomic density profile of water molecules and polar ions in the system as a function of the number of water molecules per amphiphilic (nW). We also study the dependence of the water layer thickness and the profiles of water dipole orientation with this parameter. 相似文献
54.
Fluorescence Studies on Potential Antitumoral Heteroaryl and Heteroannulated Indoles in Solution and in Lipid Membranes 总被引:1,自引:0,他引:1
Elisabete M. S. Castanheira Ana S. Abreu M. Solange D. Carvalho Maria-Jo?o R. P. Queiroz Paula M. T. Ferreira 《Journal of fluorescence》2009,19(3):501-509
Fluorescence properties of three potential antitumoral compounds, a 3-(dibenzothien-4-yl)indole 1, a phenylbenzothienoindole 2 and a 3-(dibenzofur-4-yl)indole 3, were studied in solution and in lipid aggregates of dipalmitoyl phosphatidylcholine (DPPC), dioleoyl phosphatidylethanolamine
(DOPE) and egg yolk phosphatidylcholine (Egg-PC). The 3-(dibenzofur-4-yl)indole 3 exhibits the higher fluorescence quantum yields in all solvents studied (0.32 ≤ ΦF ≤ 0.51). All the compounds present a solvent sensitive emission, with significant red shifts in alcohols. The results point
to an ICT character of the excited state, more pronounced for compound 1. Fluorescence (steady-state) anisotropy measurements of the compounds incorporated in lipid aggregates of DPPC, DOPE and
Egg-PC indicate that the three compounds are deeply located in the lipid bilayer, feeling the difference between the rigid
gel phase and fluid phases. 相似文献
55.
56.
The reaction of fluoride with thorium—SPADNS lake was studied in detail with particular reference to the effects of pH and media. Two methods for the determination of microgram amounts of fluoride based on the reaction are described. The spectrophotometric method developed is more suitable for routine use, but the colorimetric titration method is less sensitive to the effect of large amounts of electrolyte. 相似文献
57.
Quancard J Labonne A Jacquot Y Chassaing G Lavielle S Karoyan P 《The Journal of organic chemistry》2004,69(23):7940-7948
The amino-zinc-ene-enolate cyclization reaction is a straightforward route to the synthesis of 3-substituted prolines. Herein we report the application of this reaction to the syntheses of proline chimeras of lysine, glutamic acid, glutamine, arginine, and serine. All these compounds were obtained in enantiomerically pure form and suitably protected for peptide synthesis. 相似文献
58.
Sagan S Quancard J Lequin O Karoyan P Chassaing G Lavielle S 《Chemistry & biology》2005,12(5):555-565
We examined the effect of simultaneously incorporating proline or proline-amino acid chimeras in positions 9, 10, and/or 11 of substance P, on the affinity for the two NK-1 binding sites and on second-messenger activation. Because these 3-substituted prolines constrain not only the (phi,psi) values of the peptide backbone, but also the chi space of the amino acid side chain, we were able to gather data on the structural requirements for high-affinity binding to the NK-1 receptor. We were able to confirm that this C-terminal component is crucial and that it should adopt an extended conformation close to a polyproline II structure when bound to the receptor. The partial additivity of these constraints, more specifically, for the NK-1M site, suggests that the peptide backbone flexibility around the hinge-point residue Gly9 is essential to subtly position crucial side chains. 相似文献
59.
John H. Aupers Zahid H. Chohan Philip J. Cox Solange M. S. V. Doidge-Harrison Alan Howie Abdullah Khan Gavin M. Spencer James L. Wardell 《Polyhedron》1998,17(25-26)
Ionic compounds, [Q] [R2SnX(dmit)][dmit=1,3-dithiole-2-thione-dithiolate; Q=1,4-dimethylpyridinium or tetraalkylammonium; R=Phor alkyl; X=Cl, Br, I, NCS, NCSe, or N3] have been obtained by (a) from R2SnX2 and [Q]2[Zn(dmit)2] in the presence of excess QX,(b) from halide exchange reactions in acetone solution between [Q] [R2SnCl(dmit)]and a halide or pseudohalide source, or (c) by addition of QX to [R2Sn(dmit)]. Crystalstructure determinations of [NEt4] [Ph2SnI(dmit)] and [1,4-Me2pyridiniuml [Ph2SnBr(dmit)] as well as of the mixed halides, [1a, 1b, 4a, 2] [Ph2SnClnI1−n(dmit)] (n=0.57, 0.42 or0.22), indicated that the tin atoms have distorted trigonal bipyramidal geometries in the anions,with the X ligand and a dithiolato atom in the axial sites. The [R2SnX(dmit)]− anions remain essentially intact in organic solvents, but lose X− on extractionwith H2O to give the neutral species, R2Sn(dmit). 相似文献
60.
Fernando de C. da Silva James L. Wardell Solange M. S. V. Wardell Vitor F. Ferreira John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):o568-o571
The title compounds, namely 6‐methoxy‐3,3‐dimethyl‐3H‐benzo[f]chromene, C16H16O2, (III), and racemic 3‐bromo‐2,2,6,6‐tetramethyl‐3,4‐dihydro‐2H,6H‐1,5‐dioxatriphenylene, C20H21BrO2, (IV), were both synthesized in one‐step regioselective Wittig reactions from substituted 1,2‐naphthoquinones. The new ring in both compounds adopts a screw‐boat conformation. A single π–π stacking interaction links the molecules of (III) into centrosymmetric dimeric aggregates, and a single C—H...π(arene) hydrogen bond links the molecules of (IV) into centrosymmetric dimers. 相似文献