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Mixed Solvents (mixed + solvent)
Selected AbstractsEffect of LiClO4 and LiCl Additives on the Kinetics of Anionic Polymerization of Methyl Methacrylate in Toluene-Tetrahydrofuran Mixed SolventMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2003Mahua G. Dhara Abstract The kinetics of anionic polymerization of MMA has been studied at ,78,°C in toluene-THF (9:1 v/v) using 1,1,-diphenylhexyl lithium as initiator in the presence of lithium perchlorate and lithium chloride as Lewis acid additives. The control of the polymerization is lost in the absence of additives as evident from the non-linear first-order time-conversion plot and polymers with broad multimodal molecular weight distribution. The presence of LiClO4 and LiCl in 10:1 and 5:1 ratio, respectively, over the initiator brings about sufficient control, yielding polymers of narrow unimodal distribution throughout the polymerization. The reaction in the presence of the additives follows first-order kinetics free of termination and transfer. Moreover, the order with respect to the active centers is found to be almost unity, which signifies a probable disaggregation of ion-pairs to a single complexed propagating species. GPC elugrams at different conversions for MMA polymerization in the presence of LiClO4. [source] Recrystallization and Shape Control of Crystals of the Organic Dye Acid Green 27 in a Mixed SolventCHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2007Huai-Ping Cong Abstract Recrystallization of the unstructured dye acid green 27 (AG27) in a mixed solvent of alcohol (ethanol or methanol) and water was systematically studied. The results demonstrated that AG27 crystals with uniform sizes and controllable shapes can be produced by simply changing the volume ratio of ethanol (or methanol) and deionized water (DIW). Rodlike and shuttlelike AG27 crystals can be selectively synthesized. The XRD analyses revealed the periodic structures of the organic crystals. Furthermore, crystallization in another mixed solvent of N,N -dimethylformamide (DMF) and DIW results in the formation of longer fibers with high aspect ratio, which further validates the remarkable effects of mixed solvent on the shape of the AG27 crystals. This method of recrystallization in a mixed solvent is expected to facilitate the synthesis of other functional organic crystals with unusual shapes. [source] Spectroscopic Properties of Quercetin Derivatives, Quercetin-3- O -rhamnoside and Quercetin-3- O -rutinoside, in Hydro-organic Mixed SolventsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Hai-Bo Liu The characteristic fluorescence properties of quercetin-3- O -rhamnoside (QCRM) and quercetin-3- O -rutinoside (QCRT) were studied in CH3OH,H2O and CH3CN,H2O mixed solvents. Although QCRM and QCRT are known as nonfluorescent molecules, significant fluorescence emissions were discovered at 360 nm in CH3OH and CH3CN when they were promoted to the second excited state. The emission band is broad and structureless and the intensity decreases quickly as the H2O composition in the solvent increases. When the amount of H2O exceeds 60% in both mixed solvents, this emission disappears due to the formation of the distorted excited state. This state will be formed due to the strong intermolecular hydrogen bonding between the polar groups of solute and H2O. As the composition of CH3OH or CH3CN in solvent becomes large, the number of molecules having several intramolecular hydrogen bonding increases. Some of these molecules will be changed to a fluorescent species during the decay process, after excitation. The theoretical calculation further supports these results. The change of the lifetimes, quantum yields, and radiative and nonradiative rate constants of molecules was also examined as a function of solvatochromic parameters for CH3OH,H2O and CH3CN,H2O. [source] Acoustical Properties of Binary Mixtures of Heptane with Ethyl Acetate or Butyl AcetateCHINESE JOURNAL OF CHEMISTRY, Issue 3 2010Divya Shukla Abstract Mixed solvents rather than single pure liquids are of utmost practical importance in chemical and industrial processes as they provide an ample opportunity for the continuous adjustment of desired properties of the medium. Therefore, ultrasonic velocity (u) and density (,) were measured for the binary mixtures formed by heptane with ethyl acetate or butyl acetate at temperatures 293, 298 and 303 K over the entire composition range. Deviation in ultrasonic velocity (,u), deviation in isentropic compressibility (,,s), and excess intermolecular free length (LEf) have been evaluated using the ultrasonic velocity data and the computed results were fitted to the Redlich-Kister polynomial equation. The values of ,u, ,,s and LEf were plotted against the molar fraction of heptane. The observed positive and negative values of excess parameters were discussed in terms of molecular interaction between the components of the mixtures. Experimental values of ultrasonic velocity and density were compared with the results obtained by theoretical estimation procedures. The results were discussed in terms of average absolute deviation (AAD). [source] Low-Temperature Synthesis of Phase-Pure 0D,1D BaTiO3 Nanostructures Using H2Ti3O7 TemplatesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2010Duk Kyu Lee Abstract One-dimensional (1D) barium titanate (BaTiO3) nanowires, which were uniformly covered with 0D BaTiO3 nanocrystals, were synthesized by using a simple solvothermal reaction of protonated trititanate (H2Ti3O7) nanowires with barium hydroxide octahydrate [Ba(OH)2·8H2O] at 80 °C in ethanol/water mixed solvent systems. The compositions of the mixed solvents , the volume ratio of ethanol to deionized water , was a key controlling parameter in order to determine the phase formation and primary particle size of the 0D BaTiO3 nanocrystals. Single-phase cubic perovskite BaTiO3 started to form at 80 °C in a mixed solvent containing more than approximately 60,% by volume of ethanol. Field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) analysis revealed that the as-prepared BaTiO3 retained its wire-shaped morphology with nanocrystals on the surface. Furthermore, the synthetic mechanism of the 0D-1D BaTiO3 nanostructures was demonstrated in view of the dielectric tuning of the mixed solvent and the similarities between the crystal structures of BaTiO3 and H2Ti3O7. [source] Electron-Rich Alcohol-Soluble Neutral Conjugated Polymers as Highly Efficient Electron-Injecting Materials for Polymer Light-Emitting DiodesADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Fei Huang Abstract We report the design and synthesis of three alcohol-soluble neutral conjugated polymers, poly[9,9-bis(2-(2-(2-diethanolaminoethoxy) ethoxy)ethyl)fluorene] (PF-OH), poly[9,9-bis(2-(2-(2-diethanol-aminoethoxy)ethoxy)ethyl)fluorene- alt -4,4,-phenylether] (PFPE-OH) and poly[9,9-bis(2-(2-(2-diethanolaminoethoxy) ethoxy)ethyl)fluorene- alt -benzothiadizole] (PFBT-OH) with different conjugation length and electron affinity as highly efficient electron injecting and transporting materials for polymer light-emitting diodes (PLEDs). The unique solubility of these polymers in polar solvents renders them as good candidates for multilayer solution processed PLEDs. Both the fluorescent and phosphorescent PLEDs based on these polymers as electron injecting/transporting layer (ETL) were fabricated. It is interesting to find that electron-deficient polymer (PFBT-OH) shows very poor electron-injecting ability compared to polymers with electron-rich main chain (PF-OH and PFPE-OH). This phenomenon is quite different from that obtained from conventional electron-injecting materials. Moreover, when these polymers were used in the phosphorescent PLEDs, the performance of the devices is highly dependent on the processing conditions of these polymers. The devices with ETL processed from water/methanol mixed solvent showed much better device performance than the devices processed with methanol as solvent. It was found that the erosion of the phosphorescent emission layer could be greatly suppressed by using water/methanol mixed solvent for processing the polymer ETL. The electronic properties of the ETL could also be influenced by the processing conditions. This offers a new avenue to improve the performance of phosphorescent PLEDs through manipulating the processing conditions of these conjugated polymer ETLs. [source] Distinct Nanostructures from a Molecular Shuttle: Effects of Shuttling Movement on Nanostructural MorphologiesADVANCED FUNCTIONAL MATERIALS, Issue 1 2009Weidong Zhou Abstract A solvent driven molecular shuttle that contains a TCBD chromophore and in which the macrocycle can be positioned close to or far from the TCBD unit with a change of solvent is prepared. Several distinct nanostructures are obtained by control of the shuttling movement of the macrocycle: i) in a mixed solvent of CHCl3/n -C6H14 (1/1, v/v), the macrocycle locates at the peptide station, and interlaced nanofibers form as a result of the extended intermolecular dipole,dipole interactions of the TCBD units; ii) in a solvent of dimethyl sulfoxide, the macrocycle moves along the long alkyl-chain, and worm-like nanoparticles form because the macrocycle obstructs the intermolecular dipole,dipole interactions of the TCBD units. This system confirms that the molecular aggregation behaviors can be controlled by the shuttling movement of the macrocycle. Exploitation of the molecular shuttle to control the molecular aggregation behaviors will provide greater understanding in the field of molecular shuttle applications. [source] A Mild and Efficient Method for N -Arylnucleobase Synthesis via the Cross-Coupling Reactions of Nucleobases with Arylboronic Acids Catalyzed by Simple Copper SaltsHELVETICA CHIMICA ACTA, Issue 6 2008Lan Tao Abstract A simple and efficient copper-salt catalyzed N -arylation of nucleobases is reported. In a mixed solvent of MeOH and H2O, the coupling products were obtained in moderate to excellent yields at room temperature within a short time. A variety of substituted N -aryl nucleobases can be prepared through this procedure. [source] Polymer-Controlled Crystallization of Unique Mineral SuperstructuresADVANCED MATERIALS, Issue 4 2010Shao-Feng Chen Abstract The origin of complex superstructures of biomaterials in biological systems and the amazing self-assembly mechanisms of their emergence have attracted a great deal of attention recently. Mimicking nature, diverse kinds of hydrophilic polymers with different functionalities and organic insoluble matrices have been designed for the morphogenesis of inorganic crystals. In this Research News, emerging new strategies for morphogenesis and controlled crystal growth of minerals, that is, selective adsorption and mesoscale transformation for highly ordered superstructures, the combination of a synthetic hydrophilic polymer with an insoluble matrix, a substrate, or the air/solution interface, and controlled crystallization in a mixed solvent are highlighted. It is shown that these new strategies can be even further extended to morphogenesis and controlled crystallization of diverse inorganic or inorganic,organic hybrid materials with structural complexity, structural specialties, and improved functionalities. [source] A facile route to the synthesis of 1,4-pyranonaphthoquinone derivatives under microwave irradiation without catalystJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2009Xing-Han Wang A series of 1,4-pyranonaphthoquinone derivatives were synthesized via the reaction of arylidenemalononitrile and 2-hydroxynaphthalene-1,4-dione in the mixed solvent of N,N-dimethylformamide and glacial acetic acid (HOAc) under microwave irradiation without catalyst. This protocol has the notable advantages of short reaction time, high yield, and convenient operation. J. Heterocyclic Chem., (2009). [source] An efficient synthesis of new benzo[1,,2,:6,7]quinolino[2,3- d]-pyrimidine derivatives via three-component microwave-assisted reactionJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2008Yan Chen A series of benzo[1,,2,:6,7]quinolino[2,3- d]pyrimidine derivatives were synthesized via condensation of an aromatic aldehyde, 2-hydroxy naphthalene-1,4-dione and 2,6-diaminopyrimidin-4-one in mixed solvent of acetic acid and glycol (3:1,V:V) under microwave irradiation. This one-pot protocol has the advantage of good yield (86-91%), simple workup procedure and rapid reaction time (4-8min). [source] Photoamination of 1-hydroxyanthraquinone in a water-acetonitrile mixed solventJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 4 2009Masahiro Tajima Abstract We investigated the photoamination kinetics of 1-hydroxyanthraquinones in a water-acetonitrile mixed solvent by stationary light irradiation. The progression of the reaction under an inert atmosphere demonstrated the existence of additional reaction pathways. The excited triplet state of the base form of the 1-hydroxyanthraquinones was found to be responsible for the additional pathways. On the other hand, the same reaction under air involved an attack of the amine-derived radical species (aminium and amino radicals) on the ground state of the 1-hydroxyanthraquinones. One of the pathways preferentially led to 2-amination, and the other led exclusively to 4-amination. Results also indicate the attainment of an equilibrium state between the aminium and amino radicals. Copyright © 2008 John Wiley & Sons, Ltd. [source] Electrogenerated chemiluminescence of benzo 15-crown-5 derivativesJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2009Xiao Jiang Abstract Novel electrogenerated chemiluminescence (ECL) reagents C1, C2, and C3 with high fluorescence quantum yields bearing 15-crown-5 moiety have been synthesized and characterized. The photophysical, electrochemical, and ECL characters of these compounds have been studied in a 1:1 (v/v) PhH/MeCN mixed solvent. The ECL intensity is enhanced distinctly with the increase in the fluorescence quantum yield. Their ECL behaviors have been studied using annihilation and co-reactant methods (tri- n -propylamine (TPrA) was used as a co-reactant), respectively. The stable ECL emissions of compounds C1,C3 can be ascribed to the typical and simple monomer ECL emission via S-route. Copyright © 2008 John Wiley & Sons, Ltd. [source] Preparation of single-walled carbon nanotubes-induced poly(p -oxybenzoyl) crystalsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2008Kazufumi Kobashi Abstract Crystallization of oligomers was applied for the preparation of single-walled carbon nanotubes (SWNTs)/poly(p -oxybenzoyl) (POB) crystals using SWNTs as a nucleating agent. Polymerization conditions were investigated to induce the crystallization of POB oligomers through SWNTs. SWNTs/POB plate-like or lozenge-shaped crystals were successfully prepared by direct polymerization of p -hydroxybenzoic acid (HBA) in a mixed solvent of DMF/Py with TsCl in the presence of functionalized SWNTs. The size of the plate-like crystals were ,200 nm to 3 ,m. The crystals consisted of some layers, ,3 nm thick plates. Model reactions showed that esterification reactions proceed between functionalized SWNTs and HBA monomers in the polymerization system. The obtained crystals exhibited unique morphology and high crystallinity, producing a novel SWNT/POB hybrid. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1265,1277, 2008 [source] Preparation of a Monodispersed Suspension of Barium Titanate Nanoparticles and Electrophoretic Deposition of Thin FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2004Juan Li A transparent and stable monodispersed suspension of nanocrystalline barium titanate was prepared by dispersing a piece of BaTiO3 gel into a mixed solvent of 2-methoxyethanol and acethylacetone. The results of high-resolution transmission electron microscopy (HR-TEM) and size analyzer confirmed that the BaTiO3 nanoparticles in the suspension had an average size of ,10 nm with a narrow size distribution. Crystal structure characterization via TEM and X-ray diffraction indicated BaTiO3 nanocrystallites to be a perovskite cubic phase. BaTiO3 thin films of controlled thickness from 100 nm to several micrometers were electrophoretic deposited compactly on Pt/Ti/SiO2/Si substrates. The deposited thin film had uniform nanostructure with a very smooth surface. [source] Ultrafine Electrospun Polyamide-6 Fibers: Effects of Solvent System and Emitting Electrode Polarity on Morphology and Average Fiber DiameterMACROMOLECULAR MATERIALS & ENGINEERING, Issue 9 2005Pitt Supaphol Abstract Summary: In the present contribution, polyamide-6 (PA-6) solutions were prepared in various pure and mixed-solvent systems and later electrospun with the polarity of the emitting electrode being either positive or negative. The PA-6 concentration in the as-prepared solutions was fixed at 32% w/v. Some of the solution properties, i.e., shear viscosity, surface tension, and conductivity, were measured. Irrespective of the polarity of the emitting electrode, only the electrospinning of PA-6 solution in formic acid (85 wt.-% aqueous solution) produced uniform electrospun fibers, while solutions of PA-6 in m -cresol or sulfuric acid (either 20 or 40 wt.-% aqueous solution) did not. In the mixed-solvent systems, formic acid (85 wt.-% aqueous solution) was blended with m -cresol, sulfuric acid (either 20 or 40 wt.-% aqueous solution), acetic acid, or ethanol in the compositional range of 10,40 vol.-% (based on the amount of the minor solvent). Generally, the average fiber diameter increased with increasing amount of the minor solvent or liquid. Interestingly, the diameters of the fibers obtained under the negative electrode polarity were larger than those obtained under the positive one. Optical images of electrospun fibers from solutions of polyamide-6 in a mixed solvent of 85 wt.-% formic acid and 20 vol.-% m -cresol under positive (left) and negative (right) electrode polarity. [source] Chemoenzymatic Synthesis of Amylose-Grafted ChitosanMACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2007Shun-ichi Matsuda Abstract An amylose-grafted chitosan has been synthesized by a chemoenzymatic method according to the following two reactions. First, maltoheptaose is introduced to chitosan by a reductive amination using sodium cyanotrihydroborate in a mixed solvent of 1.0 mol,·,L,1 aqueous acetic acid and methanol at room temperature to produce a maltoheptaose-grafted chitosan that has a well-defined molecular structure. A phosphorylase-catalyzed enzymatic polymerization of , - D -glucose 1-phosphate is then performed from the maltoheptaose-grafted chitosan to obtain the amylose-grafted chitosan. This material does not dissolve in any solvent, e.g., aqueous acetic acid and dimethyl sufoxide, which are good solvents for chitosan and amylose, respectively. [source] Effects of Ionic Liquid [Me3NC2H4OH]+[ZnCl3], on , -Radiation Polymerization of Methyl Methacrylate in Ethanol and N,N -DimethylformamideMACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2005Guozhong Wu Abstract Summary: Radiation-induced polymerization of methyl methacrylate (MMA) in ethanol (EtOH) and N,N -dimethylformamide (DMF) in the presence of ionic liquid [Me3NC2H4OH]+[ZnCl3], is reported. A substantial increase in monomer conversion and molecular weight is observed at room-temperature ionic liquid (RTIL) >60 vol.-%, and the resulting PMMA has a broad multimodal MWD. A clear difference in the MWD pattern is noted between EtOH/RTIL and DMF/RTIL systems, probably due to the complicated interactions between the solvent and ionic liquid. Gel permeation chromatography traces of poly(methyl methacrylate) obtained by radiation polymerization in EtOH/RTIL and DMF/RTIL mixed solvent. Organic/RTIL (v/v): 1) 100:0; 2) 80:20; 3) 60:40; 4); 40:60; 5) 0:100. [source] Recrystallization and Shape Control of Crystals of the Organic Dye Acid Green 27 in a Mixed SolventCHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2007Huai-Ping Cong Abstract Recrystallization of the unstructured dye acid green 27 (AG27) in a mixed solvent of alcohol (ethanol or methanol) and water was systematically studied. The results demonstrated that AG27 crystals with uniform sizes and controllable shapes can be produced by simply changing the volume ratio of ethanol (or methanol) and deionized water (DIW). Rodlike and shuttlelike AG27 crystals can be selectively synthesized. The XRD analyses revealed the periodic structures of the organic crystals. Furthermore, crystallization in another mixed solvent of N,N -dimethylformamide (DMF) and DIW results in the formation of longer fibers with high aspect ratio, which further validates the remarkable effects of mixed solvent on the shape of the AG27 crystals. This method of recrystallization in a mixed solvent is expected to facilitate the synthesis of other functional organic crystals with unusual shapes. [source] Liquid-liquid-solid Equilibrium for Two Quaternary Systems Potassium Chloride+Rubidium Chloride+1/2-Propanol+Water at 25 °CCHINESE JOURNAL OF CHEMISTRY, Issue 12 2008Hai-Yan GUO Abstract The phase equilibria of two quaternary systems K+, Rb+//Cl-1/2-C3H7OH, H2O have been investigated at 25 °C. The liquid-solid phase equilibrium of ternary system KCl+RbCl+H2O has been determined. The liquid-liq- uid-solid phase equilibrium of the five different KCl/RbCl mass factions (from 1/0, 0.75/0.25, 0.5/0.5, 0.25/0.75 to 0/1) in the mixed solvent of 1/2-C3H7OH-H2O was investigated. The integrated phase diagrams were drawn for two quaternary systems and the salting effects of the 1/2-C3H7OH were discussed. The results of the fitting for liquid- liquid data by a five-coefficient equation and the tie line data by the Eisen-Joffe equation are reasonable. [source] Synthesis and structure of the first protonated zincoborophosphate: (H3O)Zn(H2O)2BP2O8·H2OCHINESE JOURNAL OF CHEMISTRY, Issue 9 2003Heng-Zhen Shi Abstract The solid acid of the first protonated zincoborophosphate, (H3O) Zn (H2O)2BP2O8·H2O (1), was soventothermally synthesized by the reaction of Zn(NO3)2 ± 6H2O and H3BO3 with H3PO4 in a mixed solvent, and structurally characterized by single-crystal X-ray diffraction analysis. It crystallizes in the hexagonal P6122, a = 0.9604(4) nm, c = 1.5297(6) nm, V = 1.2218(8) nm3, Dc = 2.921 g/cm3, Z = 6, F (000) = 1080, , =3.495 mm,1. The structure features that the tetrahedra-tetrahedra helices interconnected by octahedra and strong hydrogen bond interactions form a three-dimensional framework. The protonated water molecules are located at unique positions. Other characterizations by IR and thermal analysis are also described. [source] Synthesis, Crystal Structure of Cis -dioxo-catecholatotungsten(VI) Complex and Its NMR Studies on the Interaction with ATPCHINESE JOURNAL OF CHEMISTRY, Issue 6 2003Lu Xiao-Ming Abstract Cis -dioxo-catecholatotungsten(VI) complex anion [W(VI)O2 -(OC6H2O)]2- was obtained with discrete protonated ethylene-diamine (NH2CH2CH2NH3)+ cations by the reaction of tetra-butyl ammonium decatungstate with catechol in the mixed solvent of CH3OH, CH3CN and ethylenediamine, and compared with its molybdenum analogue [Mo(v)O2(OC6H4O)2]3- by crystal structure, UV, EPR. The results of the UV and EPR spectra show that tungsten is less redox active than molybdenum since the molybdenum is reduced from Mo(VI) to Mo(V) but tungsten stays in the original highest oxidized state Mo (VI) when they are crystallized from the solution above. It is worthy to note that [W(VI)O2(OC6H4O2)]2- shows the same coordination structure as its molybdenum analogue in which the metal center exhibits distorted octahedral coordination geometry with two cis -dioxocatecholate ligands and might have the related coordination structure feature with the cofactor of flavoenzyme because [Mo(v)O2(OC6H4O)2]3- presented essentially the same EPR spectra as flavoenzyme. The NMR studies on the interaction of the title complex with ATP reveal that the reduction of W(VI) to W(V) occurs when the title complex is dissolved in D2O and the W (V) is oxidized again when ATP solution is mixed with original solution and the hydrolysis of the catechola-to ligand take places at mean time being monitored by 1H NMR and 13C NMR spectra. [source] Syntheses and Crystal Structure of a New 3D Ag (I)-Fumaric Acid Framework, [Ag (hmt) (fma)1/2 · 2H2O]nCHINESE JOURNAL OF CHEMISTRY, Issue 6 2003Bi Wen-Hua Abstract A new silver (I) coordination polymer, [Ag(hmt) (fma)1/2 · 2H2O]n (1), (hmt = hexamethylenetetramine, fma = furmaric acid), was obtained by self-assembly of hmt, fma and AgNO3 in the mixed solvent of methanol, dichloromethane and water (CH3OH:CH2Cl2:H2O = 5:5:1), and characterized by X-ray diffraction analysis. Complex 1 belongs to orthorhombic space group Pbcn with cell parameters a = 1.72043(5) nm, b=1.19704(2) nm, c = 1.11685(3) nm, V = 2.30007(10) nm3, Z = 8, CCDC number: 194381. In complex 1, each hmt ligand acts as a ,3 -bridge to link three Ag(I) atoms and in turn every Ag(I) ion attaches to three hmt ligands to produce a 2D honeycomb network, which is further linked by the bidentate fma ligands to form a 3D noninterpenetrating open framework with one-dimensional channels being filled by guest molecules. [source] Transformation of a zinc inclusion complex to wurtzite ZnS microflowers under solvothermal conditionsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2010Liwei Mi Abstract Wurtzite zinc sulfide (ZnS) microflowers were synthesized successfully by a convenient solvothermal route in ethylene glycol (EG) and ethylenediamine (EN) using thiourea and zinc inclusion complex as starting materials. The inclusion complex {[Zn(bipy)2(H2O)2](4-Cl-3-NH2 -C6H3SO3)2(bipy) (H2O)2}n was achieved by the reaction of zinc oxide (ZnO) and 4-Cl-3-NH2 -C6H3SO3 with the bridging ligand bipy under moderate conditions, in which bipy is 4,4,-bipyridine and 4-Cl-3-NH2C6H3SO3NH is 4-Chloro-3-aminobenzene sulfonic acid. The phase purity of bulk products was confirmed by powder X-ray diffraction and element analysis. The factors that might affect the purity of the ZnS product during the synthesis were discussed in detail. It was found that the products were significantly affected by the mixed solvents and the starting materials. X-ray single crystal diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) were used to characterize the products. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Comparison of different algorithms to calculate electrophoretic mobility of analytes as a function of binary solvent compositionELECTROPHORESIS, Issue 10 2003Abolghasem Jouyban Abstract Ten different mathematical models representing the electrophoretic mobility of analytes in capillary electrophoresis in mixed solvents of different composition have been compared using 32 experimental data sets. The solvents are binary mixtures of water-methanol, water-ethanol and methanol-ethanol, respectively. Mean percentage deviation (MPD), overall MPD (OMPD) and individual percentage deviation (IPD) have been considered as comparison criteria. The results showed that a reorganized solution model, namely the combined nearly ideal binary solvent/Redlich-Kister equation, is the most accurate model among other similar models concerning both correlation ability and prediction capability. [source] Low-Temperature Synthesis of Phase-Pure 0D,1D BaTiO3 Nanostructures Using H2Ti3O7 TemplatesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2010Duk Kyu Lee Abstract One-dimensional (1D) barium titanate (BaTiO3) nanowires, which were uniformly covered with 0D BaTiO3 nanocrystals, were synthesized by using a simple solvothermal reaction of protonated trititanate (H2Ti3O7) nanowires with barium hydroxide octahydrate [Ba(OH)2·8H2O] at 80 °C in ethanol/water mixed solvent systems. The compositions of the mixed solvents , the volume ratio of ethanol to deionized water , was a key controlling parameter in order to determine the phase formation and primary particle size of the 0D BaTiO3 nanocrystals. Single-phase cubic perovskite BaTiO3 started to form at 80 °C in a mixed solvent containing more than approximately 60,% by volume of ethanol. Field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) analysis revealed that the as-prepared BaTiO3 retained its wire-shaped morphology with nanocrystals on the surface. Furthermore, the synthetic mechanism of the 0D-1D BaTiO3 nanostructures was demonstrated in view of the dielectric tuning of the mixed solvent and the similarities between the crystal structures of BaTiO3 and H2Ti3O7. [source] Pigment Synthesis: PY181 Pigment Microspheres of Nanoplates Synthesized via Polymer-Induced Liquid Precursors (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Mater. A polymer-induced liquid precursor is used for a pigment yellow 181 crystal formed by chemical reaction in mixed solvents of water and isopropanol by direct azo coupling under the directing influence of a designed copolymer additive. This leads to a pigment with novel complex morphology and unusal properties, as shown by Cölfen et al. on page 2095. [source] PY181 Pigment Microspheres of Nanoplates Synthesized via Polymer-Induced Liquid PrecursorsADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Yurong Ma Abstract Organic pigments are important crystalline substances, and their properties and applications rely on size and shape control. Pigment Yellow 181 (PY181) is an industrial azo pigment that is light and weatherfast and suitable for high temperature processing. One disadvantage is its needle-like shape in the default , -phase, which makes the pigment difficult to process in industry, e.g., in polymer melts, where a spherical structure would be ideal. Here, we show for the first time, that polymer-induced liquid precursor structures can be formed even in association to a chemical reaction. Furthermore, it is demonstrated that biomineralization principles can be exploited for the generation of advanced functional materials, such as pigments with novel complex morphology and different properties. Stable PY181 microspheres of nanoplates in the , -phase were obtained in mixed solvents of water and isopropanol by direct azo coupling under the directing influence of a designed copolymer additive aminobenzoylaminobenzamide-acetoacetyl-poly(ethylene imine)- block -poly(ethylene glycol) (ABABA-acetoacetyl-PEI- b -PEG). [source] Influence of Decreasing Solvent Polarity (1,4-Dioxane/Water Mixtures) on the Acid,Base and Copper(II)-Binding Properties of Guanosine 5,-Diphosphate,HELVETICA CHIMICA ACTA, Issue 3 2005Emanuela The acidity constants of twofold protonated guanosine 5,-diphosphate, H2(GDP),, and the stability constants of the [Cu(H;GDP)] and [Cu(GDP)], complexes were determined in H2O as well as in 30 or 50% (v/v) 1,4-dioxane/H2O by potentiometric pH titrations (25°; I=0.1M, NaNO3). The results showed that in H2O one of the two protons of H2(GDP), is located mainly at the N(7) site and the other one at the terminal , -phosphate group. In contrast, for 50% 1,4-dioxane/H2O solutions, a micro acidity-constant evaluation evidenced that ca. 75% of the H2(GDP), species have both protons phosphate-bound, because the basicity of pyridine-type N sites decreases with decreasing solvent polarity whereas the one of phosphate groups increases. In the [Cu(H;GDP)] complex, the proton and the metal ion are in all three solvents overwhelmingly phosphate-bound, and the release of this proton is inhibited by decreasing polarity of the solvent. Based on previously determined straight-line plots of log,Kvs. pK (where R represents a non-interacting residue in simple diphosphate monoesters ROP(O,)(O)OP(O)(O,)2, RDP3,), which were now extended to mixed solvents (based on analogies), it is concluded that, in all three solvents, the [Cu(GDP)], complex is more stable than expected based on the basicity of the diphosphate residue. This increased stability is attributed to macrochelate formation of the phosphate-coordinated Cu2+ with N(7) of the guanine residue. The formation degree of this macrochelate amounts in aqueous solution to ca. 75% (being thus higher than that of the Cu2+ complex of adenosine 5,-diphosphate) and in 50% (v/v) 1,4-dioxane/H2O to ca. 60%, i.e., the formation degree of the macrochelate is only relatively little affected by the change in solvent, though it needs to be emphasized that the overall stability of the [Cu(GDP)], complex increases with decreasing solvent polarity. By including previously studied systems in the considerations, the biological implications are shortly discussed, and it is concluded that Nature has here a tool to alter the structure of complexes by shifting them on a protein surface from a polar to an apolar region and vice versa. [source] Influence of different functionalized multiwall carbon nanotubes on the mechanical properties of poly(ethylene terephthalate) fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Liming Shen Abstract Master batches with four different kinds of functionalized multiwall carbon nanotubes (MWCTs) were prepared through the mixing of MWCTs with poly(ethylene terephthalate) (PET) (0.01 : 0.99 w/w) in trifluoroacetic acid/dichloromethane mixed solvents (0.7 : 0.3 v/v) followed by the removal of the solvents in the mixture by flocculation. The results of scanning electron microscopy showed that a good dispersion of MWCTs in PET was achieved. The reinforced fibers were fabricated by the melt spinning of PET chips with small amounts of the master batch and then further postdrawing. The optimal spinning conditions for the reinforcement of fibers were a 0.6-mm spinneret hole and a 250 m/min wind-up speed. Among the four master batches, the fibers obtained from PET/master batch B made by acid-treatment had the highest enhancement of mechanical properties. For a 0.02 wt % loading of acid-treated MWCT, the breaking strength of the PET/master batch B composite fibers increased by 36.9% (from 4.45 to 6.09 cN/dtex), and the initial modulus increased by 41.2% (from 80.7 to 113.9 cN/dtex). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] | |||||||||||||||||||