A study of the structure of mixed micellar solutions based on heptaethylene glycol monotetradecyl ether and sodium (lithium) dodecyl sulfate by the small-angle neutron scattering method

The micellization in mixed aqueous systems based on a new nonionic surfactant, namely, heptaethylene glycol monotetradecyl ether (C₁₄E₇), and an anionic surfactant, namely, sodium dodecyl sulfate, sodium decyl sulfate, or lithium dodecyl sulfate, is studied by small-angle neutron scattering. Preliminary results of the investigation into the behavior of C₁₄E₇ aqueous solutions (at two concentrations, 0.17 and 0.50%) upon addition of small amounts of three different classical anionic surfactants are reported.     

Catanionic surfactants assisted synthesis of dilead pentaoxochromate nanorods

Single‐crystalline dilead pentaoxochromate (Pb₂CrO₅) with nanorod‐shape has been synthesized by adjusting the pH value of the catanionic reverse micelles formed by a cationic surfactant CTAB (hexadecyltrimethylammonium bromide) and an anionic surfactant SDS (sodium dodecyl sulfonate), followed by a hydrothermal process. The results show that reaction parameters play important roles in the formation of the single‐crystalline Pb₂CrO₅. The reaction parameters include the kinds of the surfactants, the molar ratio (r) between the mixed cationic and anionic surfactants, reaction time and temperature. The as‐synthesized products are characterized by transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM) and powder X‐ray diffraction (XRD). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

New organic–inorganic hybrid mesoporous tantalum oxophosphate and sulfonated tantalum oxophenylphosphate

Novel mesoporous organic–inorganic hybrid tantalum oxophenylphosphate has been synthesized hydrothermally by self-assembly of anionic surfactant sodium dodecyl sulfate (SDS) as structure directing agent under mild alkaline pH conditions. The mesostructure was stable on calcinations in the presence of air and during calcination at 723 K it transformed into pure mesoporous tantalum oxophosphate. Detailed characterizations including elemental analysis, solid state MAS NMR, UV–vis and FT-IR spectroscopic studies suggested the incorporation of phenyl groups in the mesoporous framework and the XRD, N₂ sorption and TEM data suggested wormhole-like mesopore structure in these novel materials. The mesoporous tantalum oxophenylphosphate can be sulfonated by fuming sulfuric acid and the sulfonated derivative showed excellent proton conductivity at room temperature.     

Self-assembly of highly crystalline spherical BiVO4 in aqueous solutions

Spherical bismuth vanadate particles are self-assembled from aqueous Bi(NO₃)₃ and NH₄VO₃ solutions by adjusting pH and tuning the amount of surfactant sodium dodecyl sulfate (SDS) via facile hydrothermal method. The BiVO₄ samples were characterized by X-ray diffraction (XRD) and the peaks suited well with the pure phase monoclinic scheelite BiVO₄. Field emission scanning electron microscopy (SEM) showed the average size of the spherical particles was 5 μm and the assembling stages in the hydrothermal synthesis process were recorded. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) revealed the nanoparticles were single crystal. FT-IR spectroscopy test results demonstrated there was no SDS left in the samples. The mechanism of the self-assembling has also been proposed.     

Crystallization kinetics of MgSO4 · 7 H2O in presence of tenside

The effect of sodium dodecyl sulfate (SDS) on crystallization kinetics and crystal habit of MgSO₄ · 7 H₂O from aqueous solutions at 25 °C was investigated in batch experiments. It highly depends on the supersaturation level. Both increasing supersaturation and rising concentration of the tenside promote the production of needle-like crystals but the influence of the driving force is much more pronounced. SDS increases the crystallization rate and the linear crystal growth rate in length direction of the crystals. To a high degree it also influences properties of the crystallizing solution such as surface tension and viscosity.     

Effects of progressive changes in organoalkoxysilane structure on the gelation and pore structure of templated and non-templated sol–gel materials

We study how progressive changes in silane structure affect the synthesis and properties of organosilicas. Tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), methyltrimethoxysilane (MTMS), bis(trimethoxysilyl)ethane (BTMSE), bis(trimethoxysilyl)hexane (BTMSH), and bis(trimethoxysilylpropyl)amine (BTMSPA) are used as precursors in non-templated base and acid-catalyzed sol–gel processes, and in templated processes with cetyltrimethylammonium bromide (CTAB) and polyoxyethylene 10 lauryl ether (C₁₂E₁₀). The gel time of materials made without templates is mainly controlled by the structure of the silane rather than its reactivity. For instance, a dangling methyl group (MTMS) inhibits gelation, while a short bridging chain (BTMSE) promotes gelation. In basic conditions, mesoporous materials are obtained with TEOS and TMOS, while microporous materials are obtained with organically modified silanes without added amine. Dipropylamine, originally added as a catalyst, in fact templates mesopores in BTMSH-derived organosilica. In acidic conditions without pore templates, all products are microporous. In the presence of CTAB, mesopore templating occurs with TEOS, TMOS, BTMSE, and BTMSPA. With C₁₂E₁₀, mesopore templating occurs with TEOS, TMOS, and BTMSE. Surprisingly, the BTMSE-based material has the most uniform mesopores of all samples in the C₁₂E₁₀ series. Mesopore templating fails when a dangling organic limits the formation of stable pore walls (MTMS) or a large hydrophobic chain disrupts the formation surfactant micelles (BTMSH).     

Synthesis of magnesium oxysulfate whiskers in the presence of sodium dodecyl benzene sulfonate

Uniform magnesium oxysulfate (5Mg(OH)₂·MgSO₄·3H₂O) whiskers with a length of 10‐15 µm and a diameter of 0.4‐1.0 µm were synthesized in the presence of sodium dodecyl benzene sulfonate (Na‐SO₃‐C₆H₄‐C₁₂H₂₅) at 200°C for 1 h, using MgSO₄·7H₂O and NaOH as the reactants. Mg(OH)₂ precursor with poor crystallization and small crystal size was formed owing to the adsorption of sodium dodecyl benzene sulfonate on the Mg(OH)₂ surface. The quick dissolution of Mg(OH)₂ precursor in the subsequent hydrothermal reaction inhibited the occurrence of the sector‐like byproduct and promoted the formation of magnesium oxysulfate whiskers with uniform morphology. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of the surfactant nature on the thermo-stability of surface modified SnO2 nanoparticles

The modification of particle surface properties by the addition of small surfactant molecules in the initial sol is one strategy to minimize the strong tendency to aggregation and coarsening of nanoparticles prepared from the sol–gel process. In this work, the effect of the nature of the surfactant, Tiron^® ((OH)₂C₆H₂(SO₃Na)₂ · H₂O, anionic) or Catechol^® (C₆H₄-1,2-(OH)₂, non-ionic) or Maptac^® ([N(CH₃)₃(CH₂)₃NHCOC(CH₂CH₃)]⁺Cl^?, cationic), grafted on the SnO₂ nanoparticles on the mesoporosity of powders fired at 600 °C is presented. SnO₂ powders were prepared from an one-pot sol–gel route in which the hydrolysis of SnCl₄ · 5H₂O in aqueous solution was carried out in presence of the surfactant. The Fourier transform infrared (FTIR) spectroscopy and gravimetric and differential thermo-analysis (TG/DTA) results show that the thermo-stability of surface grafted SnO₂ nanoparticles obeys the following series: Tiron^® > Catechol^® > Maptac^®. The N₂ adsorption isotherms results evidence that the mesopores texture (specific surface area, pore volume and average pore size) can be tuned in a controlled way by increasing the amounts of Tiron^® or Catechol^® molecules grafted on the surface of SnO₂ nanoparticles.     

Brillouin spectra of mixed alkali glasses: xCs2O(1−x)Na2O5SiO2

The Brillouin spectra of a series of mixed alkali glasses, of the composition _xCs₂O(1?x)Na₂O5SiO₂, have been measured and analyzed. Significant nonlinearities are found for the variation of the isothermal compressibility [K_T,0(T_f)] and Landau-Placzeck ratio, with a minimum observed in each as a function of x, while the longitudinal and transverse sound velocities and related elastic constants, C₁₁, C₄₄ and Young's modulus, E, vary monotonically (nearly linearly) with x. The results are interpreted in connection with related ultrasonic data and the effect of varying composition on the mechanical properties of mixed alkali glasses.     

Synthesis and Structures of Two Functionalized Isobenzofurans: (3aR,7aR,4S,5S)-1,3,3a,4,5,7a-Hexahydro-5-methyl-3-oxoisobenzofuran-4-carboxylic acid and (3aα,4β,7β,7aα)-4-[(Acetyloxy)methyl]-3a,4,7,7a-tetrahydro-7-methyl-1,3-isobenzofurandione

Abstract  

The title compounds, C₁₀H₁₂O₄ and C₁₂H₁₄O₅, were prepared as part of an ongoing study to explore the practical aspects of solventless reaction methods. As confirmed by the crystal structures, treatment of maleic anhydride with (2E,4E)-hexa-2,4-dien-1-ol or its acetate counterpart resulted in cis bicyclo [4.3.0] molecular frameworks. The racemic product derived from the dienol synthon crystallized in chiral space group P2₁2₁2₁ via a pasteurian resolution process with molecules organized by carboxyl⋯carboxyl and C–H⋯O contacts. The acetate derivative crystallizes in space group Cc.     

Structural and spectral studies on gypsum crystals under simulated conditions of phosphoric acid production with and without organic and inorganic additives

In the dihydrate process to produce phosphoric acid, phosphate ore [Ca₁₀F₂(PO₄)₆] is leached with sulfuric and weak phosphoric acids to produce phosphoric acid and gypsum as a by‐product. Crystallization of gypsum occurs as the leaching is taking place. The effect of organic and inorganic additives on the structure and spectrum of gypsum crystals under simulated conditions of phosphoric acid production is studied using x‐ray diffraction and infrared spectroscopy. Structure and spectrum of formed gypsum crystals in the absence of additives are slightly different from the standard gypsum crystals (card No. 6‐0046), which reflect the effect of preparation medium on the crystal structure of gypsum crystals. Presence of additives such as cetyl trimethyl ammonium bromide and 1,2‐dihydroxybenzene‐3,5‐disulfonic acid, Al³⁺ and Mg²⁺ increase the crystallinity of gypsum, while presence of additives such as citric acid and sodium dodecyl sulfate decrease the crystallinity of gypsum. Presence of Al³⁺ and Mg²⁺ as additives lead to the formation of calcium sulfate hemihydrate beside calcium sulfate dihydrate. Presence of sodium dodecyl sulfate as an additive inhibits the crystallization of gypsum and leads to the formation of anhydrite and calcium sulfate hemihydrate.     

Electrochemical Characteristics of “Polyaniline” Cathodes and Anodes in Aqueous Electrolytes

The quinoid-benzenoid-diimine form, (=(C₆H₄)=N-(C₆H₄)-N=)_x of “polyaniline” shows excellent cathode characteristics including recyclability when used in conjunction with a zinc anode in an aqueous electrolyte of (l. 0M ZnCl₂ + 0. 5M NH₄Cl) having a pH of ～ 4. The reduced form of this material, (-(C₆H₄)-N(H)-(C₆H₄)-N(H)-)_x can be used as an anode in conjunction with a Pb0₂ cathode in an aqueous 0.5M Pb(BF₄)₂ electrolyte.     

Mesomorphic properties of liquid crystalline compounds with chalconyl central linkage in two phenyl rings

In order to investigate the influence of the central linking group and the effect of flexibility on mesomorphism, we have synthesised a newly homologous series 3-(3-butoxyphenyl)-1-(4-n-alkoxy phenyl) prop-2-en-1-one (series-l) consisting of 13 homologues C₁–C₈, C₁₀, C₁₂, C₁₄, C₁₆ and C₁₈. In the present series, mesophase commences from the C₆ homologue. C₁–C₅ homologues did not exhibit liquid crystalline (LC) property, while C₆–C₁₂ homologues exhibited an enantiotropic nematic phase and the rest of the homologues C₁₄–C₁₈ displayed monotropic SmC and nematic mesophase. The transition temperatures of the synthesised compounds were determined by an optical polarising microscopy equipped with a heating stage. All newly synthesised compounds were confirmed by ¹H-NMR, ¹³C-NMR, IR and elemental analysis.     

Behavior of poly(ε-caprolactone)-based diblock copolymers in a bulk state and in solution

Abstract

A series of amphiphilic MOPEO-b-PCL copolymers (DBCs), based on biocompatible methoxypoly(ethylene oxide) with M_n=4.5?kDa and poly(ε-caprolactone) of a variable chain length, was synthesized by an anionic ring-opening block copolymerization. The structural investigations, performed by DSC and WAXS methods, revealed the microphase separation in DBC bulk structure and the existence of separate amorphous regions and microcrystalline domains of MOPEO and PCL blocks. Spectrophotometry and SLS were used to study the self-assembling of DBC macromolecules in selective dioxane/aqueous solution and to determine the main micellization parameters (CMC and -ΔG°). The DBC micelles morphology and their specific aggregation in mixed solvent were shown.     

EPR spectra of irradiated Na2Cr2O7 · 2 H2O crystals

The EPR spectra of X-irradiated Na₂Cr₂O₇ · 2 H₂O crystals grown from the aqueous solution at room temperature are studied. Three groups of lines are detected, which marked conventionally as C₁, C₂ and C₃. Each of the C₁ and C₂ line groups is a superposition of two doublets. The lines are interpreted as due to the Cr⁵⁺ ions in the distorted (stretched) oxygenous tetrahedron. The doublet structure is due to hyperfine interaction with nuclei of 1/2 spin which are protons of water. It is shown that the C₁ and C₂ line groups are due to the centers of the same type with different orientations in the lattice. The principal g-tensor values for these centres were as follows: g_z = 1.916, g_y = 1.978, g_x = 1.986.     

Crystal Structure of Three Isomorphous Compounds of 2,5-Dibromopyridine with Tetrahalometalate(II) Ions

Abstract  Three salts of 2,5-dibromopyridinium with metal halides, (C₅H₄Br₂N)₂[CuCl₄], (I); (C₅H₄Br₂N)₂[CuBr₄], (II); and (C₅H₄Br₂N)₂[CdBr₄], (III), are isomorphous in C2/c with cell volumes 1864.5(8), 1974.6(4) and 2072.9(7) ?³, respectively. For the Cu cases (I) and (II) the discrete [MX₄]²⁻ anions are strongly distorted with max/min tetrahedral angles of 131.19(8)°/99.67(9)° and 130.24(5)°/99.36(11)°, respectively. For the Cd case (III) the distortion is much less with max/min tetrahedral angles of 115.97(3)°/105.99(4)°. The cations are planar. The short hal···hal contacts are for (I), aryl Br···anionic Cl 3.335(3) ? and 3.430(2) ?; for (II), aryl Br···anionic Br 3.473(2) ? and 3.567(2) ?; and for (III), aryl Br···anionic Br 3.452(1) ? and 3.675(1) ?. Longer aryl Br···aryl Br contacts (3.842(2) ? to 3.967(2) ? are present in the three isomorphs. Bifurcated hydrogen bonding to two anionic halides exist in the three structures with N–H···Cl 3.365(8) ? and 3.379(7) ? in (I), N–H···Br 3.539(11) ? and 3.425(11) ? in (II), and N–H···Br 3.426(5) ? and 3.387(5) ? in (III). Short ring contacts exist with the perpendicular distances between mean cation planes in (I), (II), and (III) of 3.68(6) ?, 3.56(1) ? and 3.72(1) ?, respectively. Index Abstract  An analysis is made of the competition between hydrogen bonding, halogen–halogen and halogen–halide interactions as well as differences between [CuX₄]²⁻ and [CdX_4] ²⁻ polydedra in the structures of the three isomorphs.      

Synthesis and crystal structure of the coordination compound of pyridoxine with manganese sulfate

The reaction of pyridoxine with manganese sulfate in an aqueous solution gave the coordination compound MnSO₄ · 2C₈H₁₁O₃N · 2H₂O (I). The structure of I was determined from single-crystal X-ray diffraction data. In the centrosymmetric complex (sp. gr. P[`1]P\bar 1, Z = 1), the Mn atom is coordinated by two pyridoxine molecules and two water molecules, thus adopting an octahedral coordination. The sulfate anion is also at a center of symmetry and, consequently, is disordered. The pyridoxine molecules are coordinated to the metal atom through the oxygen atoms of the deprotonated hydroxyl group and the CH₂OH group that retains the hydrogen atom. The nitrogen atom is protonated in such a way that the heterocycle assumes a pyridinium character. The crystal structure also contains six water molecules of crystallization. A thermogravimetric study showed that the decomposition of I occurs in several successive steps, such as dehydration, the combustion of organic ligands, and the formation of an inorganic residue.     

Crystal structures of N-(2-aminoethyl)-1-naphthaleneneacetamide nitrate and hydrogen tartrate dihydrate

Nitrate (1): C₁₄H₁₇N₂O⁺·NO ₃ ^– , orthorhombic, Pbca,Z=8,a=9.6924(4),b=27.664(2) andc=10.8589(6)Å.Hydrogen tartrate dihydrate (2): C₁₄H₁₇N₂O⁺·C₄H₅O ₆ ^– ·2H₂O, orthorhombic, P2₁2₁2₁,Z=4,a=7.6703(5),b=7.9368(4) andc=31.953(2)Å. In the solid state, cation conformation differ due to molecular flexibility, very different anionic environments, and resultant hydrogen bonding patterns. Despite these differences, the two structures maintain the same separations (about 7.35 Å) of the two most distant potential pharmacophoric groups, i.e., the aromatic ring and the protonated amine group.     

Ionic conductvity and NMR investigation of quaternary glasses in the ZrF4BaF2ThF4LiF system

The existence of glasses involving large amounts of LiF (up to 60%) within the ZrF₄BaF₂ThF₄LiF quaternary systems has allowed the authors to study the evolution of transport properties with varying LiF content.A minimum of ionic conductivity bound to a maximum of activation energy has been detected when the atomic Li/F ratio is equal to ≅ 0.07. In the Li-low concentration domain, σ increases regularly and ΔE decreases simultaneously when the BaF₂ concentration increases; on the contrary in the Li-high concentration region log σ and ΔE are quasi-linear functions, increasing and decreasing respectively, of the LiF rate.A ⁷Li and ¹⁹F NMR investigation has shown that Li⁺ and F⁻ ions are simultaneously mobile and the temperature dependence of the number of mobile F⁻ ions has been determined. In the Li-low concentration domain transport properties result from mixed contributions of mobile Li⁺ and F⁻ ions, for high Li concentrations they depends only on the Li⁺ rate.Glasses with high Li-content have good electrical performnces (e.g. σ_175°C ≅ 2.10⁻⁴ω⁻¹ cm⁻¹ for Zr_0.20Ba_0.10Li_0.60Th_0.10F₂).     

Photochemical synthesis and crystal structure of two potentially useful metal carbonyl complexes: pentacarbonyl(η2-cis-cyclooctene)-tungsten(0) and tetracarbonylbis(η2-cis-cyclooctene)tungsten(0)

W(CO)₅(C₈H₁₄) and W(CO)₄(C₈H₁₄)₂ were synthesized photochemically from W(CO)₆ andcis-cyclooctene with a respective yield of 71% and 18%. The compounds were characterized by NMR, IR and single X-ray crystallography. The IR spectra of the two compounds exhibited characteristic bands for the mono- and bis-substituted metal carbonyl complexes. In W(CO)₄(C₈H₁₄)₂, thecis-cyclooctene ligands are in atrans configuration with the double bonds perpendicular to each other. The two crystal structures were refined toR=0.040 for W(CO)₅(C₈H₁₄) and 0.025 for W(CO)₄(C₈H₁₄)₂. Although the tungsten-carbon (of the carbonyl groups) distances are very similar in both structures, the distances between the tungsten atom and the olefinic carbons are shorter in W(CO)₄(C₈H₁₄)₂, 2.36 Å, than in W(CO)₅(C₈H₁₄), 2.51 Å.