Synthesis of Hydrotalcite using Magnesium from Seawater and Dolomite

Abstract

Three methods of synthesizing hydrotalcite(HT) have been developed using magnesium from seawater and dolomite(MgCa(CO₃)₂). In the first process, 1.0M Na₂CO₃solution was added to calcium ion free artificial seawater containing AlCl₃ with an initial Mg/Al molar ratio of 2.0～3.7 until a pH of 10 was obtained. The solution was then continuously stirred for Ih at 60°C. CO₃ ^2--HT was precipitated as a single phase, and the initial Mg/Al molar ratio, which each recovery of Mg²⁺and Al³⁺ from the solution was above 98%, was 2.0–2.3. In the second process, a Ca(OH)₂ slurry was added to artificial seawater containing AlCl₃ with an initial Mg/Al molar ratio of 1.0～5.0 until a pH of 10.5 was obtained, and then was stirred for Ih at 60°C. HT was also precipitated as a single phase with initial Mg/Al molar ratio 2.0～4.0. The initial Mg/Al molar ratio, which each recovery of Mg²⁺ and Al³⁺ from the solution was above 98%, was 2.2～3.3, but SO₄ ^2- and Cl^? were contained in the precipitated HT. When HT was produced using initial Mg/Al molar ratio of 3.0 at 25°C, SO₄ ^2- and Cl^?in the HT were ion-exchanged with CO₃ ^2- in a 0.05M Na₂CO₃solution for 24h at 25°C, and SO₄ ^2- and Cl^? content of the HT were decreased to 0.5 and 0.05wt%, respectively. In the third process, dolomite calcined at 1000°C was added to an AlCl₃ solution with an initial Mg/Al molar ratio of 1.0～2.0, and the solution was stirred for 1～4h at 25～90°C. HT was precipitated with the smallest amount of MgO and Mg(OH)₂ when the initial Mg/Al molar ratio was 1.5 and the solution was stirred for 4h at 90°C.     

Hydrogen Intercalation in Potassium-C60

Abstract

Solid state ¹H NMR of (KH)₃C₆₀ was measured in the temperature range between ?80 and 60 °C. A doublet spectrum composed of main peak at ?7.0 ppm and shoulder peak at ～0 ppm was observed at room temperature. The negative chemical shift of the main peak indicates that hydrogen in (KH)₃C₆₀ exists as a hydride-like ion. The 60 °C spectrum became singlet at ?5.8 ppm due to motional narrowing.     

Adsorption of Carboxylic Acids by Diethylenetriamine Intercalation Compound of α-Zr(HPO4)2 · H2O

Abstract

Two kinds of diethylenetriamine (2E3A) intercalation compounds of α-zirconium phosphate with different interlayer distances could be obtained by regulating the reaction time and temperature. Phase I (d = 10.2 Å) slowly transforms to Phase II(d = 15. 8 Å) with transformation enthalpy of 30 kJ-mol^?1 in 2E3A aqueous solution. The conformation of 2E3A in Phase I and Phase II were confirmed to be bent and all trans (straight) forms by³¹P MAS NMR and XRD measurements. Two phases have different adsorption behavior for gaseous carboxylic acids. Phase II can adsorb considerable amount of carboxylic acids whereas Phase I adsorb a little.     

Structural Influence on the Intensitiy Ratio of the T′ and T87Rb NMR Lines and the Superconductivity in Rb3C60

Abstract

The intensity ratio of the T′/T⁸⁷Rb NMR lines in Rb₃C₆₀ could be changed by different cooling rates after annealing at 380 °C. The results are discussed with respect to magnetically different surroundings of the Rb ions through the two standard orientations of the C₆₀ ^3-ions. Additionally, the superconducting volume fraction is influenced by the different cooling procedures.     

Crystal structure, vibrational spectra, and thermal decomposition and nitrogen adsorption behaviour of a new tetramanganese(II) dipyrophosphate decahydrate, Mn4(P2O7)2·10H2O

A new manganese(II) pyrophosphate, Mn₄(P₂O₇)₂·10H₂O, has been synthesized and characterized by single-crystal X-ray diffraction [orthorhombic space group Pnma, with unit cell parameters of a=9.3288(3) ?, b=25.9532(9) ?, c=8.4783(3) ?; Z=4]. All the pyrophosphate anions show non-linear P–O–P bonds with an average angle of 128.60°. The framework of this new pyrophosphate is made up of packed layers of MnO₆ octahedra connected by double-tetrahedra P₂O₇ groups and a layer of Mn(H₂O)₆ units. The [P₂O₇]⁴⁻ anions adopt a bent, near-staggered conformation. The absence of coincidences for the majority of the IR and Raman bands is in accord with the centrosymmetric structure of the material. The vibrational spectra have been interpreted in part on the basis of factor group effects. The structural changes occurring during heating have been investigated by TG-ATD. When Mn₄(P₂O₇)₂ ^.10H₂O is gradually heated, it decomposes into an intermediate hydrated salt at 96°C and then to anhydrous Mn₂P₂O₇ at 325°C. This thermal behaviour is different from that of Zn₄(P₂O₇)₂·10H₂O. The crystal structure of the new managenese(II) pyrophosphate is compared with the known structures of Zn₄(P₂O₇)₂·10H₂O, Mn₂P₂O₇·2H₂O and anhydrous Mn₂P₂O₇. The adsorption and desorption isotherms of Mn₄(P₂O₇)₂·10H₂O, Zn₄(P₂O₇)₂·10H₂O and MnKHP₂O₇·2H₂O have been investigated by BET measurements and the results show that the capacity for N₂ sorption of the Mn(II) salt is two times lower than is that of the Zn(II) isotype and two or three times higher than is that of MnKHP₂O₇·2H₂O.     

X-ray structure and NMR assignment of 4,4′-[3-oxa-1,5-pentanedi(ylthio)]-3,3′-diquinolinyl sulfide

The title compound (C₂₂H₁₈N₂OS₃) is monoclinic, with a=20.7446(5), b=8.332(1), c=24.393(7)°, β=112.12(1)° and space group P2₁/n. There are two independent molecules in the unit cell. Two quinoline moieties are nearly perpendicular to each other (76.9(1)°) and (72.0(2)°). Both S-methylene fragments are trans-orientated with respect to the C(3)−S(1)−C(13) plane. Two pairs of sulfur atoms in ortho-positions are in very close contact with sulfide preserving a skew conformation. The central 12-membered ring adopts an unusual conformation. Part XLIII in the series of Azinyl Sulfides. Part XLII: Maślankiewicz, M.J.; Maślankiewicz, A.J. Heterocycl. Chem. 1996,33, 1989.     

Enhanced persistent photoconduction in CuInS2–ZnIn2S4 alloys single crystals and processes of its relaxation

ABSTRACT

Photoelectrical response in CuInS₂–ZnIn₂S₄ alloys single crystals was analysed in the low temperature region from 30 K up to 100 K. The molar ratio of ZnIn₂S₄ in the alloys was varied in the range 0 mol%?16 mol%. The crystals with up to 12 mol% were the single-crystalline, meanwhile those with 16 mol% were the two phase ones. We have analysed spectral distribution of their photocurrent at different temperatures and the following relaxation towards the stationary values. The photo-induced photoconductivity phenomena were identified. Moreover the long-lasting relaxations with characteristic times exceeding 1.5×10³ sec were observed at lowest temperatures. They used to shorten exponentially with increasing temperature showing thermally activated behaviour. The main parameters of the photoconductivity kinetics and their temperature dependencies were determined. The observed behaviour was explained by the slow multicenter recombination due to the combined effect of different trapping and recombination centers. The effects of both – “fast” and “slow” recombination centers were taken into account.     

Synthesis and crystal structure of anhydrous copper suberate: [Cu<Subscript>2</Subscript>(OOC-(CH<Subscript>2</Subscript>)<Subscript>6</Subscript> -COO)<Subscript>2</Subscript>]

The title compound [Cu₂(OOC-(CH₂)₆-COO)₂] was synthesized and its crystal structure has been determined by single crystal X-ray diffraction methods. The complex crystallizes in the triclinic space group P-1 with a=5.1077(5) ?, b=8.362(2) ?, c=11.378(2) ?, α=93.773(6)°, β=97.587(9)°, γ=90.493(’9)° and D _cal=1.629 mg/m³ for Z=1.  The structure is polymeric and consists of discrete anhydrous centrosymmetric binuclear units [Cu₂(OOC-(CH₂)₆-COO)₂]. The two copper(II) centres bridged by the suberate groups in a syn-syn conformation, are in pentacoordinated distorted square-pyramidal coordination environment, with an intramolecular Cu–Cu distance of 2.5793(10) ?. Each binuclear unit, related to the next through μ_oxo bridges with a Cuμ_oxo–Cuμ_oxo separation of 3.2326(10)?, defines infinite chains of one-edge sharing CuO₅ square pyramid.     

Intercalation of O2 and its Effect on the Properties of C60 and C70 Solids

Abstract

The intercalation of O₂ in C₆₀ and C₇₀ solids have been studied. In both gas effusion spectra of C₆₀ and C₇₀ powder exposed to O₂ at room temperature, two evolution peaks of O₂ are found near 80 and 150°C. In both C₆₀ and C₇₀ powder, the peak near 80°C does not depend on a heating ratio and the peak near 150°C shifts to higher temperature with the heating ratio. The activation energy on diffusion of O₂ in C₆₀ and C₇₀ solids are ～0.27eV and ～0.46eV, respectively. The number of O₂ intercalated in C₇₀ powder is larger than that in C₆₀ powder. Electron spin density of 02-intercalated C₆₀ film is larger than that of C₇₀ film. The effect on the properties of C₆₀ and C₇₀ solids by the intercalation of O₂ are discussed.     

Crystal Structure and Vibrational Spectra of Erbium Trisodium Bis(Cyclotriphosphate) Nonahydrate,ErNa<Subscript>3</Subscript>(P<Subscript>3</Subscript>O<Subscript>9</Subscript>)<Subscript>2</Subscript> · 9H<Subscript>2</Subscript>O

Abstract The cyclotriphosphate salt, ErNa₃(P₃O₉)₂ · 9H₂O, has been characterized by single-crystal X-ray diffraction [hexagonal, space group , with unit cell parameters of a = b = 30.8451(14), c = 12.8063(8) ?; Z = 18]. The structure consists of alternating layers of [P₃O₉]³⁻ groups, ErO₈ dodecahedra, Na(1)O₆ and Na(2)O₇ polyhedra linked together by water molecules. The P₃O₉ rings are grouped along the c-axis in a P₃O₉–ErO₈ arrangement thereby producing broad, hexagonal channels of diameter of 6.65 ? with a side dimension of 3.907 ?. The absence of coincidences for the majority of the IR and Raman bands observed for the cyclotriphosphate salt is in accord with the centrosymmetric structure of the material. The vibrational spectra have been interpreted on the basis of factor group effects. Graphical abstract We report the crystal structure and vibrational spectra of erbium trisodium bis(cyclotriphosphate)nanohydrate salt ErNa ₃ (P ₃ O ₉ ) ₂ · 9H ₂ O H. Assaaoudi, M. Ijjaali, A. Ennaciri, I. S. Butler* and J. A. Kozinski Crystal structure and vibrational spectra of erbium trisodium bis(cyclotriphosphate) nonahydrate,ErNa₃(P₃O₉)₂ · 9H₂O. Projection of the coordination polyhedra of ErNa₃(P₃O₉)₂ · 9H₂O down the c axis     

Synthetic nanodiamonds (SNDs) containing bimetallic Ni(Co)–Fe composites: preparation,characterization and catalytic performance in the reaction of CO2 methanation

Abstract

In this article, we present the preparation, characterization, and catalytic performance of bimetallic Co₉₃Fe₀₇ and Ni₈₀Fe₂₀ active mass loaded on synthetic nanodiamonds (SNDs) in the carbon dioxide (CO₂) methanation. The pristine SNDs possessing a developed specific surface are thermally stable and inert to the reaction mixture of CO₂ and dihydrogen. However, it is shown that 100% conversion of CO₂ into methane can be reached at the lower temperature than that for a massive Co₉₃Fe₀₇ or Ni₈₀Fe₂₀ catalyst when 20?wt.% of the catalyst mass was loaded on the surface of SNDs. The catalytic activity of the prepared bimetallic/SNDs composites is estimated as the minimum temperature at the maximum conversion of CO₂ at atmospheric pressure: it is 325 and 290?°C for Co₉₃Fe₀₇/SNDs and Ni₈₀Fe₂₀/SNDs, respectively. Thermal desorption studies showed that the methanation over Co-Fe/SNDs and Ni-Fe/SNDs catalysts run through the stage of CO₂ dissociation into carbon and oxygen atoms and their subsequent interaction with hydrogen to form methane and water molecules. Scanning electron microscopy studies have shown that the presence of transition metal-rich sites on the surface of the carrier contributes to the improvement of efficiency of the Ni₈₀Fe₂₀ catalyst action.     

Redetermination of the crystal structure of [Na4(H2O)14]SnS4: a compound containing a novel chain of aquated sodium ions

[Na₄(H₂O)₁₄]SnS₄ is obtained by the reaction of Na₂S·9H₂O with SnCl₄·5H₂O in aqueous solution at 21°C. It crystallizes in the space group Cc with a = 8.621(2) Å, b = 23.543(5) Å, c = 11.358(2) Å, = 110.58(3)° and V = 2158.2 ų with Z = 2. Refinement of 3826 unique reflections from a racemically twinned crystal yielded a final value of R₁ = 0.0464 (|F| > 4) and wR₂ = 0.104 and a goodness of fit of 1.125. The structure consists of a Na⁺/H₂O network supporting the tetrahedral SnS₄ ^4– anions. Water molecules or sulfide ions octahedrally coordinate each of the four crystallographically independent Na⁺ ions. The dominant feature of the structure is the existence of zigzag chains of edgeshared Na octahedra. These chains are tied together into a three-dimensional network by bridging Na(H₂O)₆ octahedra and individual H₂O molecules.     

Magnetic Susceptibility of Deintercalated Tunnel Compound of KxCr5Se8 and Mössbauer Spectra of Kx(Cr0.95 57Fe0.05)5Se8

Abstract

KCr₅Se₈ has a TIV₅S₈-type structure, containing K ions in one-dimensional tunnels. Deintercalated samples of K_xCr₅Se₈ (0.32 ≤ x ≤ 0.93) were prepared by leaching method using Alc₃/FeCl₃ aqueous solution. These samples showed a broad peak of magnetic susceptibility at ca. 130 K. ⁵⁷Fe-Mössbauer spectra of K_x(Cr_0.95 ⁵⁷Fe_0.05)₅Se₈ (x = 1.0, 0.49) showed a quadrupole doublet at 300 K. Magnetic sextets appeared at 4.2 K in both samples, indicative of magnetic ordering. The observed isomer shift indicated that the charge of Fe is +3 in both samples. It was proposed that Se^2- was partially oxidized by the deintercalation.     

Nano-composite soda lime silicate glass prepared using silver ion exchange

Commercial soda lime silicate glasses have been subjected to ion exchange at different temperatures ranging from 320 to 500 °C in a molten mixture of AgNO₃ and NaNO₃ with molar ratio of 10:90, 02:98 and 50:50 for different time periods ranging from 40 to 180 min. Optical and structural properties of the ion exchanged glass are measured using UV–Vis–NIR absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy and transmission electron microscopy (TEM). Signature of silver nanoparticle formation is obtained from the UV–Vis–NIR spectra, which shows a peak at 425 nm due to surface plasmon resonance (SPR). Replacement of Na⁺ ions by Ag⁺ ions is inferred from FTIR spectra. Fluorescence spectra reveal the formation of Ag⁰ atoms from Ag⁺ ions at higher temperatures. TEM image shows the silver nanoparticles of average size 3.75 nm. At exchange temperature of 500 °C Ag nanoparticles are formed without post-exchange annealing treatment.     

Study the cooperative noncovalent interactions in Lithium-1, 10-Phenanthroline complex,its DFT calculations and Hirschfield surface analysis

The new compound [Li(NO₃)(phen)]_n (phen: 1,10-phenanthroline) has been synthesized and characterized by elemental analysis, and single crystal X-ray diffraction. The Li⁺ ion is five coordinated occupied distorted TBP (trigonal bipyramidal) geometry. The Li⁺ ions are bridged by nitrate anions into 1D polymeric chain. The nitrate anions are coordinated to Li⁺ ions through chelating and bridging bidentate mode of binding. There are cooperative noncovalent interactions like strong or weak H-bonding, weak π···π and C?H···π interactions are involved to form 2D network. Thermal properties of this complex have been completely described by thermo gravimetric analysis (TGA). Both molecular and crystal structures of this compound were compared and discussed the intermolecular interactions by using Hirshfeld surface analysis and 2D-fingerprint plots. The optimized molecular geometry by DFT calculations agrees closely with obtained from the crystallographic study. Hirshfeld surface analysis of compound (I) indicates that H···H, π···π and C?H···π contacts can account for 30.9, 15.0 and 7.4% respectively of the total Hirshfeld surface area.     

Preparation and Characterization of [Zn(H2O)6][Zn2V10O28(H2O)10]?·?6H2O Single Crystals with a Novel Metallic Heteropolyoxoanion

Abstract  The compound investigated in this study contains a novel centrosymmetric heteroanion [Zn₂V₁₀O₂₈(H₂O)₁₀]²⁻. This cluster results from the connection between a V₁₀O₂₈ group and two Zn(2)O(OH₂)₅ octahedra. The Zn(1)O₆ octahedron and three water molecules associated with it are located between the different layers. The [Zn(H₂O)₆][Zn₂V₁₀O₂₈(H₂O)₁₀] · 6H₂O compound belongs to P-1 space group, with a = 8.967(2) ?, b = 10.390(4) ?, c = 12.338(13) ?, α = 108.31(7)°, β = 100.68(7)°, γ = 103.00(3)°, V = 1022(1) ?³ and Z = 1. Refinement gave R = 0.035 and wR(F²) = 0.098 for 3837 unique observed reflexions [I > 2σ(I)]. Index Abstract  The compound investigated in this study contains a novel centrosymmetric heteroanion [Zn₂V₁₀O₂₈(H₂O)₁₀]²⁻. This cluster results from the connection between a V₁₀O₂₈ group and two Zn(2)O(OH₂)₅ octahedra.      

Structural and Morphological Characterization of Pt/WO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>–ZrO<Subscript>2</Subscript> Catalysts

Abstract  Catalysts of Pt/WO _x –ZrO₂ type with 1 wt% of Pt and 10, 15 and 20 wt% of tungsten were synthesized and characterized. The structural and morphological features of these catalysts were studied. The samples were synthesized by impregnation method and calcined at 600 °C, 700 °C and 800 °C. The characterizations were carried out using different techniques: X-ray diffraction, Raman spectroscopy, scanning electronic microscopy, nitrogen adsorption measurement and refinement of their crystalline structures by Rietveld method. X-ray diffraction patterns revealed the formation ZrO₂ and WO₃ crystalline structures and its crystallite size were determined. The zirconium oxide crystallized into tetragonal and monoclinic phases and tungsten trioxide crystallized into monoclinic phase. Crystalline WO₃ and amorphous WO _x species were detected by Raman spectra. Index Abstract  Catalysts of Pt/WO _x –ZrO₂ type with 1 wt% of Pt and 10, 15 and 20 wt% of tungsten were synthesized and characterized. The structural and morphological features of these catalysts were studied. The samples were synthesized by impregnation method and calcined at 600 °C, 700 °C and 800 °C. The characterizations were carried out using different techniques: X-ray diffraction, Raman spectroscopy, scanning electronic microscopy, nitrogen adsorption measurement and refinement of their crystalline structures by Rietveld method. X-ray diffraction patterns revealed the formation ZrO₂ and WO₃ crystalline structures and its crystalline size were determined. The zirconium oxide crystallized into tetragonal and monoclinic phases and tungsten trioxide crystallized into monoclinic phase. Crystalline WO₃ and amorphous WO _x species were detected by Raman spectra.     

Low-Temperature Form (Phase II) of Ionic Conductor Ag7TaS6 Analyzed using High-Resolution Synchrotron X-Ray Powder Diffraction Data

Abstract

The ternary sulfide Ag₇TaS₆ displays high Ag-ion conductivity at ambient temperature, and the framework TaS₆ and Ag ions can be respectively regarded as the host structure and guest ions. Two low-temperature phases, i.e. Ag₇TaS₆ II and Ag₇TaS₆ III, were found. The Rietveld analysis of Ag₇TaS₆ II has been performed based on the X-ray data measured at 240K using a wave length 0.64997Å by a high-resolution powder diffraction instrument combined with the beam line BMlB at the European Synchrotron Radiation Facilities. Smooth convergence has been obtained (R_WP=0.066), and the crystal structure was described based on a space group Pn with monoclinic lattice constants a=7.4462, b=7.4013, c=10.5296Å and β=90.069°. The narrow widths of reflections even at high angle have made possible the analysis of individual thermal parameters for Ag ions. In Ag₇TaS₆ II, Ag-Ag linkage rather than Ag-S coordination seem to affect the thermal parameters of Ag ions. The guest-guest interaction can be important for mobility of guest ions in the ionic conductor.     

Synthesis and crystal structure of (+)-(2R,3R)-N, N′-bis-trityl-2,3-bis-aziridine

A new C₂ symmetric bis-aziridine derivative was synthesized starting from L-(+)-tartaric acid. The molecular structure of (+)-(2R, 3R)-N, N-bis-trityl-2,3-bis-aziridine 4, was determined by ¹H, ¹³C NMR and elemental analysis and was confirmed by single-crystal X-ray diffraction. Crystal data for 4: C₄₂H₃₆N₂, orthorhombic, space group: P2₁2₁2₁, a = 12.7633(14), b = 14.5661(6), c = 17.4184(14) Å, and Z = 4.