New host–guest supramolecular coordination polymers based on [(Me3Sn)3Fe(CN)6]n with alkali metal iodides and their applications as electrode materials in batteries

The metal iodides reduce partially the host coordination polymer of the type $ ^{ 3}_{\infty } \left[ {\left( {{\text{Me}}_{ 3} {\text{Sn}}} \right)_{ 3} {\text{Fe}}\left( {\text{CN}} \right)_{ 6} } \right] $ , I, to give new host–guest supramolecular coordination polymers (SCP). The physical and chemical characteristics of the new products were studied by elemental analyses, X-ray powder diffraction, IR, UV/Vis, and solid state NMR spectra. The host–guest SCP are [M_x(Me₃Sn)₃Fe_(1–x)^IIIFe _x ^II (CN)₆]_n M = Li⁺·2H₂O, 1; Li⁺, 2; Na⁺, 3; K⁺, 4; Cu⁺, 5, [Li(Me₃Sn)₃Fe^II(CN)₆]_n, 6 and [(LiDEE)_0.9(Me₃Sn)₃Fe _o.1 ^III Fe _o.9 ^II (CN)₆]_n, 7. The stoichiometry and nature of the guest depend on the type of the metal iodide and the reaction conditions. The polymeric nature of these SCP is due to the presence of trigonal bipyramidal configured structure which bridges between the single d-transition metal ions. The host–guest SCP containing the Li ions have been tested as electrodes to construct four different lithium-ion batteries.     

Influence of inorganic and organic additives on the composition of the precipitate of synthetic hydroxylapatite and calcium oxalate monohydrate

Synthetic hydroxylapatites are prepared with additives, such as Mg²⁺, CO ₃ ^2? , and C₂O ₄ ^2? . An increase in the concentration of magnesium leads to the formation of struvite. In the Ca(NO₃)₂-(NH₄)HPO₄-Na₂CO₃-NH₄OH-H₂O system, an excess of carbonate ions leads to the formation of calcite. When the synthesis is performed using oxalate ions as additives, calcium oxalate does not form the inherent phase. Calcium oxalate monohydrate is synthesized with additives, such as CO ₃ ^2? , HPO ₄ ^2? , and SO ₄ ^2? ions and urea, glycine, and glutamic acid. X-ray powder diffraction analysis has revealed that the composition of the CaC₂O₄ · H₂O precipitate remains unchanged under these conditions and in the presence of the aforementioned additives.     

Photocatalytic removal of methyl orange in an aqueous solution by a WO3/TiO2 composite film

WO₃/TiO₂ composite film was prepared by microarc oxidation technique and characterized by SEM, XRD, UV-vis spectra and Zeta-potential. The photocatalytic activity of WO₃/TiO₂ composite film was evaluated by examining the degradation of methyl orange. The influence of solution pH and inorganic anions on removal ratio of methyl orange was investigated. Removal ratio of methyl orange decreased with an increase of pH value in acidic solution, while it increased with the pH value in alkaline solution. The influence of added anions on the removal ratio is divided into two aspects. Addition of Cl^? and SO ₄ ^2? resulted in a decrease in photocatalytic removal ratio of methyl orange, while it was facilitated by PO ₄ ^3? , HCO ₃ ^? and NO ₃ ^? .     

Synthesis and single-crystal structure of lead oxide nanoclusters in zeolite Y, |Pb 15.5 2+ (Pb4O4(Pb 16/19 2+ Pb 3/19 4+ )4)4.75|[Si117Al75O384]-FAU

A single crystal of excessively Pb²⁺-exchanged zeolite Y (|Pb _15.5 ²⁺ (Pb₄O₄(Pb _16/19 ²⁺ Pb _3/19 ⁴⁺ )₄)_4.75|[Si₁₁₇Al₇₅O₃₈₄]-FAU) was prepared by exchange of Na–Y (|Na₇₅|[Si₁₁₇Al₇₅O₃₈₄]-FAU, Si/Al = 1.56) with an aqueous stream 0.05 M Pb(C₂H₃O₂)₂ at 294 K, followed by vacuum dehydration at 1 × 10^?6 Torr and 693 K. Its structure was determined at 100 K, by X-ray diffraction techniques in the cubic space group Fd $ \overline{3} $ 3 ¯ m and was refined to the final error indices R ₁/wR ₂ = 0.0639/0.1323. About 53.5 Pbⁿ⁺ ions per unit cell occupy three different equipoints; 26 are at site I′, 19 are at site II, and the remaining 8.5 are at another site II. Three Pb⁴⁺ ions at some of the positions must have higher oxidation states due to elevated dehydration temperature; Pb(IIa) is supposed to coexist with Pb²⁺ and Pb⁴⁺ ions assuming the charge balance of the zeolite framework. A distorted Pb₄O₄ cube, alternating Pb²⁺ at Pb(I′) and O^2? at O(5), coordinates with four Pb²⁺ and/or Pb⁴⁺ ions through its oxygen atoms to give a [Pb ₄ ²⁺ O ₄ ^2? (Pb _16/19 ²⁺ Pb _3/19 ⁴⁺ )₄]^176/19+ cluster in 4.75 of eight sodalite cavities per unit cell in zeolite Y.     

Mass spectrometry study of glasses based on sulfur, phosphorus, and arsenic

The mass spectrometry study of chalcogenide glasses in the P-S binary system and P-As-S ternary system is used to demonstrate that the composition of the gas phase in binary samples is characterized by the conventional spectra of ions, such as PS ₂ ⁺ , P₂S ₇ ⁺ , P₂S ₇ ⁺ and P₄S ₁₀ ⁺ . The introduction of As to the binary glass systems first demonstrated the presence of ions AsPS⁺, AsPS ₄ ⁺ , AS_{2 5} ⁺ and As₂PS₅ ⁺ in the gas phase of the ternary chalcogenide system, which correspond to the ternary compositions AsPS₄ and As₂P₂S₇ in the solid phase.     

Synthesis and Crystal Structures of a Lanthanum(III) 1D Polymer and a Mixed-Ligand Cerium(III) Binuclear Complex Derived from Pyridine-2,6-dicaboxylic Acid

Lanthanum(III) and cerium(III) complexes of pyridine-2,6-dicaboxylic acid (H₂Pydc) have been prepared and their crystal structures were determined by X-ray crystallography. The single crystal analysis reveals that the lanthanum(III) complex, 1 is polymeric consisting of {[La(Pydc)₂(H₂O)₂]·4H₂O} _n units linked through carboxylate oxygen atoms and exhibiting nine coordination number. Intermolecular O–H···O hydrogen bonds produce R ₁ ¹ (6), R ₄ ⁴ (16) and R ₄ ⁴ (20) rings, which lead to three-dimensional polymeric chains. The crystal structure of the cerium(III) complex, 2 [{Ce(Pydc)₃}{Ce(Pydc)(HO–CH₂CH₂–OH)(H₂O)₃}·6H₂O)] shows that the complex is a mixed-ligand binuclear system in which one cerium coordinated to three Pydc molecules, while the other cerium is bound to one Pydc, one oxygen atom of the other Pydc, one ethylene glycol and three water molecules. Each of the two Ce(III) ions is nine coordinated. Intermolecular O–H···O hydrogen bonds produce R ₂ ² (8) and R ₂ ² (20) rings, which lead to three-dimensional polymeric chains. The complexes were further investigated using elemental analysis, FTIR spectroscopy and thermogravimetric analysis.     

Effect of supplying a carbon extracting solution on denitrification in horizontal subsurface flow constructed wetlands

Denitrification strongly depends on the availability of carbon source in constructed wetlands (CWs). In this study, several relevant carbon source extracting solutions made from hydrolyzate of selected wetland litters were added to CWs for nitrogen removal enhancement. The feasibility of supplying a carbon extracting solution to improve potential denitrification rate in horizontal subsurface flow constructed wetland was deeply investigated. Combinations of different hydraulic retention time (HRT, especially for 2-day and 4-day) with different influent COD/N ratios were designed to prove the enhancement on denitrification by carbon source supplement. In addition, specific denitrification rate (SDNR) was calculated for the comparison of the nitrogen removal at different COD/N ratios. The sequential operation results on total nitrogen (TN) and nitrate (NO ₃ ^? -N) removal efficiencies were obtained in CW system with an influent COD/N ratio of 4.0. The accumulation of nitrite (NO ₂ ^? -N) was found to be closely related to the removal of NO ₃ ^? -N. Meanwhile, no obvious accumulation of NO ₂ ^? -N was found when the removal of NO ₃ ^? -N was relatively high.     

Formation and characterization of nanoporous structures on surface of LPD-derived GeO2 ceramic film

This work represents an idea of forming nanoporous structures on surface of a LPD (liquid phase deposition)-derived GeO₂ ceramic film by thermal reduction of GeO₂ under hydrogen atmosphere. SEM, XRD and Raman analyses show that well-defined nanopores with size in range of 10–100 nm have been formed on surface of GeO₂ film by annealing at 600 °C for 5–10 min. The pore formation process is furthered by structural defects which serve as active sites for the thermal reduction reaction. Fast phase transformation from hexagonal GeO₂ to tetragonal GeO₂ has occurred within the first 5 min of annealing. Green-yellow (2.32 eV) and violet (2.9 eV) photoluminescences originating from $ {\text{O}} {-} \mathop {\text{Ge}}\limits^{ \bullet \bullet } {-} {\text{O}} $ and ≡Ge–Ge≡ defects are observed in the film samples. The photoluminescence peak intensity decreases with increase of annealing time due to diminution of O/Ge ratio. The film annealed for 5 min exhibits a maximum green-yellow to violet PL peak ratio, which is related to generation of some new $ {\text{O}} {-} \mathop {\text{Ge}}\limits^{ \bullet \bullet } {-} {\text{O}} $ defects at the phase interface.     

Synthesis and Properties in Solution of Gaussian Homo Asymmetric Polysiloxanes with a Bulky Side Group

Ring opening polymerization (ROP) of 1,3,5-tri-n-hexyl,1,3,5-trimethylcyclotrisiloxane (D ₃ ^Hexa ) and 1,3,5-tri-n-heptyl,1,3,5-trimethylcyclotrisiloxane (D ₃ ^Hepta ) was promoted by acid-treated synthetic silica–alumina to obtain Gaussian homo asymmetric polysiloxanes. M_w was above 70?kg/mol, meaning that homo asymmetric bulky side-group polysiloxane chains with high molecular weight were obtained. The material was treated in an acidic medium to improve the contents of acid sites and successfully tested as an inorganic acidic catalyst for ROP of D ₃ ^Hexa and D ₃ ^Hepta cyclosiloxanes. The samples of poly(methylhexylsiloxane) (PMHS) and poly(methylheptylsiloxane) (PMHepS) obtained were structurally characterized mainly by ²⁹Si NMR. All the experimental values including the refractive index increment (dn/dc), the second virial coefficient (A₂), the square root of the mean square radius of gyration ( $ \langle {{\text{RMS}}_{\text{radius}}}^{ 2} \rangle^{ 1/ 2} $ ), the average molecular weight (M_w), the average molecular numeral (M_n), and the weight polydispersity (M_w/M_n) were obtained using a gel permeation chromatography/light scattering (GPC/LS) coupled system. The A₂ experimental value for the two polymers (between 4 and 6.5?×?10^?4?mol/mL?g²) indicated that toluene was a good solvent. In addition, PMHS and PMHepS $ \langle {{\text{RMS}}_{\text{radius}}}^{ 2} \rangle^{ 1/ 2} $ were greater than 30?nm, indicating that larger chains of high molecular weight were obtained.     

1-Hexene Double Bond Isomerization Reaction Over SO 4 = Promoted NiO, Al2O3 and ZrO2 Acid Catalysts

Sulfated mixed oxides, SO ₄ ⁼ /Ni–Al–O and SO ₄ ⁼ /Zr–Al–O were evaluated for double bond isomerization (DBI) of 1-hexene using helium and hydrogen as carrier gases. The increase of temperature from 100 to 200 °C seems to favor the deprotonation pathway and contribute to increase the 1-hexene conversion for both catalysts and without regard of the carrier gas. The results indicate that temperature it is the main factor that contributes to improve both conversion and selectivity towards (cis + trans)-2-hexene, while the reductive atmosphere beneficiate only the SO ₄ ⁼ /Ni–Al–O catalyst performance, as hydrogen prevents this catalyst from a fast deactivation.     

Towards an Understanding of the Reaction Pathways in Propane Ammoxidation Based on the Distribution of Elements at the Active Centers of the M1 Phase of the MoV(Nb,Ta)TeO System

The M1 phase of the MoV(Nb,Ta)TeO system is one of the most effective catalysts for the ammoxidation and selective oxidation of propane to acrylonitrile (AN) and acrylic acid, respectively. The active centers of the M1 phase reside on the ab planes of this crystalline material (i.e., the (001) lattice face). Early on we proposed that the thus located active centers contain all key catalytic elements strategically placed for the conversion of propane to AN. These seven element comprising active centers contain: five metal oxide octahedra (2 V _0.32 ⁵⁺ /Mo _0.68 ⁶⁺ , 1 V _0.62 ⁴⁺ /Mo _0.38 ⁶⁺ , 2Mo _0.5 ⁶⁺ /Mo _0.5 ⁵⁺ ) and two Te⁴⁺??oxygen sites. In this contribution we analyze the various compositional probabilities of the seven element active centers and their additional eight element surroundings and conclude that there are 32 possible compositional arrangements of this 15 element assembly. From the diverse structural arrangements, diverse catalytic properties can be assigned to the individual sites, leading to diverse propane reaction pathways. We conclude that there are 22% AN forming, 22% propylene, 10% waste and 46% inert sites. After normalization these sites are deemed to lead to the following product yields: 41% AN, 41% propylene and 18% waste. The highest experimentally attained AN yield from propane is 42%, employing M1 phase only, which coincides with the predicted value of a concerted mechanism. Higher AN yields are, however, anticipated, up to a lofty upper limit of 82%, by allowing also for a consecutive mechanism (C₃° ?? C ₃ ⁼ ??AN). This possibility can be rationalized on the basis of the existence of vicinal C₃° ?? C ₃ ⁼ /C ₃ ⁼ ??AN sites whose presence is plentiful on the catalytically important ab planes of M1. The placement and efficiency of these sites is, however, not perfect; therefore the upper AN yield limit is not realized in practice. Our analysis of the elemental distribution at the active centers and their immediate surroundings provides us with new insights into the relationship between structure and catalytic reaction mechanisms of the M1 phase and might serve as a guide towards a redesign of the M1 composition, so as to attain higher AN yields from propane. It provides a challenging task for the synthetic chemist.     

Electrochemical study of aluminium ion reduction in acidic AlCl3-n-butyl-pyridinium chloride melts

Electrochemical reduction of AlCl₃ dissolved in acidic AlCl₃-n-butyl-pyridinium chloride melt was studied by linear sweep voltammetry and chronopotentiometry at tungsten and platinum electrodes, in the Al₂Cl ₇ ^? concentration range 0.3 to 0.5 M between 30 and 60°C. Al₂Cl ₇ ^? bulk reduction was preceded by a nucleation (tungsten) or alloy formation phenomenon (platinum). The overall results agree rather well with the mechanism: $$\begin{gathered} 2AlCl_4^ - \rightleftarrows Al_2 Cl_7^ - + Cl^ - \hfill \\ 4Al_2 Cl_7^ - + 3e \rightleftarrows Al + 7AlCl_4^ - \hfill \\ \end{gathered} $$ The electrochemical reaction appeared quasi-reversible. Calculated values of the product of the transfer coefficient by the number of the electron exchanged in the rate determining step were in the range 0.45 to 0.7. Diffusion coefficients for Al₂Cl ₇ ^? were calculated.     

Conduction in Bi2O3-based oxide ion conductor under low oxygen pressure. II. Determination of the partial electronic conductivity

In order to investigate the partial electronic conduction in the high oxide ion conductor of the system Bi₂O₃-Y₂O₃ under low oxygen pressure, e.m.f. and polarization methods were employed. Although the electrolyte was decomposed when the \(P_{{\text{O}}_{\text{2}} }\) was lower than the equilibrium \(P_{{\text{O}}_{\text{2}} }\) of Bi, Bi₂O₃ mixture at each temperature, the ionic transport number was found to be close to unity above that \(P_{{\text{O}}_{\text{2}} }\) . The hole conductivity (σ _p) and the electron conductivity (σ _p) could be expressed as follows, $$\begin{gathered} \sigma _p \Omega cm = 5 \cdot 0 \times 10^2 \left( {P_{O_2 } atm^{ - 1} } \right)^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \exp \left[ { - 106 kJ\left( {RT mol} \right)^{ - 1} } \right] \hfill \\ \sigma _p \Omega cm = 3 \cdot 4 \times 10^5 \left( {P_{O_2 } atm^{ - 1} } \right)^{ - {1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \exp \left[ { - 213 kJ\left( {RT mol} \right)^{ - 1} } \right] \hfill \\ \end{gathered} $$ These values were much lower than the oxide ion conductivity under ordinary oxygen pressure.     

Structure and reactivity of MoO3-MgO catalysts

Surface of OH groups on reduced MoO₂-MgO catalysts such as $$ - - Mg - - O - - \begin{array}{*{20}c} {||} \\ {Mo} \\ | \\ \end{array} - - OH$$ may act as an active site for hydrogenation of propene. The surface hexa-coordinated Mo⁵⁺ ion (MO _6c ⁵⁺ ) was reduced to a lower number of cation such as Mo⁴⁺ or Mo³⁺ which act as an active site for metathesis of propene.     

Characterization and Evaluation of Methylcyclopentane and Cyclohexane Ring Opening over Ir/ZrO2–MoO3 Catalysts

Methyl bromide was synthesized by reacting methane with oxygen and hydrogen bromide over Rh/SiO₂ catalyst. The reaction started from the oxidation of HBr to form active bromine species (Br^? radicals and Br* surface species), which in turn reacted with CH₄ to form CH ₃ ^? radicals and $\hbox{CH}_{3}^{\ast}$ surface species. These CH ₃ ^? and $\hbox{CH}_{3}^{\ast}$ species reacted with the active bromine species to form CH₃Br and CH₂Br₂. The presence of HBr inhibited the deep oxidation and the steam reformation of CH₄ and therefore, guaranteed the high selectivity of CH₃Br. In the presence of HBr, CO was formed from the oxidation and steam reformation of CH₃Br, while CO₂ was formed from the oxidation and steam reformation of CO over Rh/SiO₂ at reaction temperature higher than 560 °C.     

The thermoelectric power in Bi2O3

The thermo electric power, ΔE/ΔT, of the cell $$\begin{gathered} O_2 + N_{2, } Pt/Bi_2 O_3 (\delta phase)/Pt, O_2 + N_2 \hfill \\ (T + \Delta T) (T) \hfill \\ \end{gathered}$$ has been measured as a function of oxygen pressure (10^?4 atm ? p(O₂) ? 1 atm) in the temperature range 650–800° C. The experimental result can be described by: $$[ \in ({\rm O}_2 /{\rm O}^{2 - } ) - \in (e, Pt)] = [45.6 \pm 5.6 log p(O_2 ) - 261](\mu VK^{ - 1} )$$ within experimental error, where ε(O₂/O²), the Seebeck coefficient ofδ-Bi₂O₃, stands for \(\mathop {\lim }\limits_{\Delta T \to 0} \Delta E/\Delta T\) The change of ΔE/ΔT with oxygen pressure corresponds to the change of the partial molar entropy of O₂. The heat of transport of O^2? ions is calculated to be 0.13 eV ± 0.01 whereas the activation enthalpy for ionic conduction is 0.30 eV. From this discrepancy it is concluded that the free ion model of Rice and Roth cannot be applied, while the extended lattice gas model of Girvin might explain the results when strong polaron coupling is assumed.     

Heteronuclear Cu(II)–Mn(II)–Cu(II) Complex Constructed from Metallo-Ligand Through Carboxylate Oxygens: Coexistence of Water Hexamers

A heteronuclear complex of [Mn(H₂O)₄(CuL)₂]₂·4H₂O 1 (H₂L = 2-hydrogen benzaldehydeneglycylglycine) has been synthesized and characterized by IR spectra, TGA, and single crystal X-ray diffraction analysis. The molecule consists of one $\text{Mn}{(\text{H}_{2}\text{O})_{4}}^{2+}$ Mn(H₂O) ₄ ²⁺ group and two symmetric groups [CuL]^? which are connected by carboxylate oxygen atoms. A discrete water hexamer composed of a planar tetrameric water ring and two pendent water molecules acts as a ‘glue’ to assemble adjacent [CuL]^? into a two-dimensional structure.     

Photocatalytic degradation of ammonia by light expanded clay aggregate (LECA)-coating of TiO2 nanoparticles

Photocatalytic degradation of ammonia on supported TiO₂ nanoparticles was investigated. The TiO₂ nanoparticles used as photocatalyst were coated on light expanded clay aggregate granules (LECA), which is a porous and light weight support. Photocatalytic reaction activity of prepared catalyst was determined by ammonia degradation from water synthetically polluted with ammonia. Experiment results showed significantly high photocatalytic activity for the immobilized catalysts. The ammonia was removed more than 85% within 300 min of the process with optimum calcinations temperature 550 °C and pH 11. Kinetics of the photocatalytic reaction followed a pseudo-first order model. XRF, XRD and SEM analyses revealed a rather uniform coating of TiO₂ on the support. By using floated TiO₂/LECA as a photocatalyst in aqueous solution of NH ₃ ^? , the ammonia was photodegraded into N₂ and H₂ gases, while NO ₂ ^? and NO ₃ ^? were formed at very low concentrations.     

Thermodynamic diagrams of the copper/ molten potassium nitrate system

Thermodynamic diagrams for the copper/molten potassium nitrate system have been calculated and expressed either as potential/pO^2?, potential/pO ₂ ^? or potential/pO ₂ ^2? diagrams. They exhibit the corresponding immunity, active dissolution, passivity and transpassivity regions.