Synthesis and study of the phosphate Cs<Subscript>2</Subscript>Mn<Subscript>0.5</Subscript>Zr<Subscript>1.5</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>

The new phosphate Cs₂Mn_0.5Zr_1.5(PO₄)₃ was synthesized for the first time and characterized by X-ray diffraction. Its crystal structure was refined in space group P2₁3, Z = 4 at 25°C (a = 10.3163(1) Å, V = 1097.93(1) ų), by the Rietveld method using the powder X-ray diffraction data. The structure is built of an octahedral-tetrahedral framework {[Mn_0.5Zr_1.5(PO₄)₃]^2?}_3∞ with cesium atoms being located in large cavities. The hydrolytic stability of the powdered phosphate containing ¹³⁷Cs radionuclide was studied. The minimum achieved ¹³⁷Cs leaching rate was 4 × 10^?8 g/cm₂ day.     

Thermal decomposition of [Cd(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

Thermal decomposition of [Cd(NH₃)₆](NO₃)₂ was studied by thermogravimetry (TG) with simultaneous differential thermal analysis (SDTA) for two samples and at two different sets of measurement parameters. The gaseous products of the decomposition were on-line identified by evolved gas analysis (EGA) with a quadruple mass spectrometer (QMS). The decomposition of the title compound proceeds, for both cases, in the three main stages. In the first stage, deammination of [Cd(NH₃)₆](NO₃)₂ to [Cd(NH₃)](NO₃)₂ undergoes by three steps and 5/6 of all NH₃ molecules are liberated. At second stage the liberation of residual 1/6NH₃ molecules and the formation of Cd(NO₃)₂ undergoes. However, during this process simultaneously a two-step oxidation of a part of ammonia molecules also takes place. In a first step as a result a mixture of ammonia, water vapour and nitrogen is formatted. At the second step, subsequent oxidation of a next part of NH₃ molecules undergoes. As a result, a mixture of nitrogen oxide, nitrogen and water vapour is formatted, what for these both steps clearly indicates the EGA analysis. The third stage of the thermal decomposition is connected with the melting and subsequent decomposition of residual Cd(NO₃)₂ to oxygen, nitrogen dioxide and solid CdO. Additionally, third sample was measured by differential scanning calorimetry (DSC) and the results are fully consistent with those obtained by TG.     

Reaction of the novel Ru<Subscript>3</Subscript>(CO)<Subscript>10</Subscript>[Ph<Subscript>2</Subscript>P(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>Si(OEt<Subscript>3</Subscript>)]<Subscript>2</Subscript> complex on SBA-15 and MCM-41 mesoporous silicas

The reaction of Ru₃(CO)₁₂ with 2(diphenylphosphino)ethyl-triethoxysilane (DPTS) in hydrocarbons, leads to the functionalized Ru₃(CO)_12−n [Ph₂P(CH₂)₂Si(OEt₃)] _n (n = 1,2) complexes. The complex with two phosphine substituents was chemically anchored on mesoporous silicas, SBA-15 and MCM-41, in order to obtain two hybrid materials characterized by a different localization of the metal centre on the surface of the porous supports. A detailed investigation of the cluster, before and after chemical anchoring on the mesoporous silicas, was pursued. Particular attention was also devoted to the study of the morphological, structural and textural properties of the metal-functionalised silicas (Ru/SBA-15 and Ru/MCM-41) by infrared spectroscopy (FT-IR), scanning electron microscopy, X-ray diffraction and N₂ physisorption analysis.     

Crystal structure of a new ternary molybdate in the Rb<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-Eu<Subscript>2</Subscript>(MoO<Subscript>4</Subscript>)<Subscript>3</Subscript>-Hf(MoO<Subscript>4</Subscript>)<Subscript>2</Subscript> system

A ternary salt system Rb₂MoO₄-Eu₂(MoO₄)₃-Hf(MoO₄)₂ was studied in the subsolidus area by X-ray phase analysis. A novel ternary molybdate, Rb_4.98Eu_0.86Hf_1.11(MoO₄)₆, formed in the system. The Rb_4.98Eu_0.86Hf_1.11(MoO₄)₆ rubidium-europium-hafnium molybdate crystals were grown by solution-melt crystallization under the spontaneous nucleation conditions. The structure and composition of this compound were refined by single crystal X-ray diffraction (X8 APEX automated diffractometer, MoK _α radiation, 1753 F(hkl), R = 0.0183). The crystals are trigonal, a = b = 10.7264(1) Å, c = 38.6130(8) Å, V = 3847.44(9) ų, Z = 6, space group R \(\bar 3\) c. The three-dimensional mixed framework of the structure comprises Mo tetrahedra and two types of octahedra, (Eu,Hf)O₆ and HfO₆. The large cavities of the framework include two types of the rubidium atom. The distribution of the Eu³⁺ and Hf⁴⁺ cations over two crystallographic positions was refined.     

Thermokinetics on the reaction of formation of Dy[(C<Subscript>5</Subscript>H<Subscript>8</Subscript>NS<Subscript>2</Subscript>)<Subscript>3</Subscript>(C<Subscript>12</Subscript>H<Subscript>8</Subscript>N<Subscript>2</Subscript>)]

The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen?H₂O) in absolute ethanol at 298.15 K has been determined as (-16.12 ± 0.05) kJ?mol^-1 by a microcalormeter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59 ± 0.29) kJ?mol^t-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction.     

Organic-inorganic hybrid perovskite (C<Subscript>6</Subscript>H<Subscript>5</Subscript>(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>NH<Subscript>3</Subscript>)<Subscript>2</Subscript>CdCl<Subscript>4</Subscript>: Synthesis,structural and thermal properties

The present research work reports the study on crystal structure, vibrational spectroscopy and thermal analysis of organic-inorganic hybrid compound (C₆H₅(CH₂)₂NH₃)₂CdCl₄. Single crystals of bis(phenethylammonium)tetrachlorocadmate (C₆H₅(CH₂)₂NH₃)₂CdCl₄ (PEA–Cd) were obtained by diffusion at room temperature. This compound crystallizes in the orthorhombic space group C2cb with unit cell parameters a = 7.4444(2) Å, b = 38.8965(3) Å, c = 7.3737(2) Å and Z = 4. Single crystal structure has been solved and refined to R = 0.036 and wR = 0.092. The structure consists of an extended [CdCl₄]^2– network and two [C₆H₅(CH₂)₂NH₃]⁺ cations to form a two-dimensional perovskite system. The infrared (IR) spectrum of the title compound was recorded at room temperature. Differential scanning calorimetry (DSC) was used to investigate the phase transition; this compound exhibits a reversible single solid-solid phase transition.     

Thermal behavior of Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/TiO<Subscript>2</Subscript> mesoporous gels

Summary Titania-based photocatalytic materials were prepared by sol-gel method using Fe³⁺ and polyethyleneglycol (PEG₆₀₀) as additives. Thermogravimetry (TG), differential thermal analysis (DTA) and evolved gas analysis (EGA) with MS detection were used to elucidate processes that take place during heating of Fe³⁺ containing titania gels. The microstructure development of the Fe₂O₃/TiO₂ gel samples with and without PEG₆₀₀ admixtures was characterized by emanation thermal analysis (ETA) under in situ heating in air. A mathematical model was used for the evaluation of ETA results. Surface area and porosity measurements of the samples dried at 120&deg;C and the samples preheated for 1 h to 300 and 500&deg;C were compared. From the XRD measurements it was confirmed that the crystallization of anatase took place after thermal heating up to 600&deg;C.     

Orientational disorder in crystal structures of (NH<Subscript>4</Subscript>)<Subscript>3</Subscript>ZrF<Subscript>7</Subscript> and (NH<Subscript>4</Subscript>)<Subscript>3</Subscript>NbOF<Subscript>6</Subscript>

Crystal structures of (NH₄)₃ZrF₇ (I) and (NH₄)₃NbOF₆ (II) are refined by X-ray diffraction at room temperature. The compounds are isostructural and belong to the structural type of elpasolite: space group F23; a(I) = 9.4185(3) Å, a(II) = 9.3371(5) Å; V(I) = 835.50(5) ų, V(II) = 814.02(8) ų; Z = 4; R(I) = 0.0145, and R(II) = 0.0138. The refinement of the structures in the space group Fm3m yields abnormally short X-X distances in the pentagonal bipyramid MX₇ (X = F, O). The oxygen atom in II is identified by Nb-X distances and occupies one of the axial vertices of the bipyramid. The Nb atom in II is statistically distributed over the position 24f, while Zr in I resides in the symmetry center. The pentagonal bipyramid MX₇ has six independent orientations in I and twelve in II. One of three crystallographically independent ammonium groups of the structures is disordered over six or twelve equivalent orientations.     

Structure and some properties of [UO<Subscript>2</Subscript>CrO<Subscript>4</Subscript>{CH<Subscript>3</Subscript>CON(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>}<Subscript>2</Subscript>]

A new complex [UO₂CrO₄{CH₃CON(CH₃)₂}₂] (I) was studied by thermal analysis, IR spectroscopy, and X-ray crystallography. The crystals are monoclinic: a = 13.8108(11) Å, b = 8.6804(7) Å, c = 13.0989(10) Å, β = 104.777(1)°, V = 1518.4(2) ų, space group P2₁/c, Z = 4, R = 2.39%. The structure of I contains infinite chains of the [UO₂CrO₄{CH₃CON(CH₃)₂}₂] composition running along [001]; the complex belongs to the AT¹¹M¹ ₂ crystal-chemical group (A = UO ₂ ²⁺ , T¹¹ = CrO ₄ ^2? , M¹ = CH₃CON(CH₃)₂) of uranyl complexes. The chains are linked into a three-dimensional framework due to hydrogen bonds between oxygen atoms of chromate ions and hydrogen atoms of methyl groups of the dimethylacetamide.     

Synthesis and structure of [UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>){CONH<Subscript>2</Subscript>N(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>}<Subscript>2</Subscript>]

The single crystals of [UO₂(C₂O₄){CONH₂N(CH₃)₂}₂] were synthesized and studied by X-ray diffraction. The crystals are monoclinic, a = 7.461(2) Å, b = 8.828(2) Å, c = 11.756(2) Å, β = 107.21(3)°, space group Pc, Z = 2, R = 2.94%. The structure comprises infinite chains [UO₂(C₂O₄){CONH₂N(CH₃)₂}₂] extended along [001] and corresponding to the AT¹¹M ₂ ¹ crystallochemical group (A = UO ₂ ²⁺ , T¹¹ = C₂O ₄ ^2? , M¹ = N,N-CONH₂N(CH₃)₂) of uranyl complexes. The chains are connected into a three-dimensional framework by hydrogen bonds involving the oxygen atoms of oxalate and uranyl ions and the N,N-dimethylcarbamide methyl groups.     

Phase diagram of the system KF-K<Subscript>2</Subscript>TaF<Subscript>7</Subscript>-Ta<Subscript>2</Subscript>O<Subscript>5</Subscript>

As an asymmetric organic molecular crystal, p-N,N-dimethylaminobenzaldehyde (DAB) exhibits peculiar optical property. It was first grown by solution technique adopting slow evaporation method at room temperature using CCl₄ as growth medium. The solubility of DAB increases with temperature. Good quality transparent crystals of p-N,N-dimethylaminobenzaldehyde were carefully collected and subjected various characterization studies such as UV, FTIR, ¹H and ¹³CNMR spectral studies and thermal (TG-DTG) studies to determine the purity and application oriented properties of the grown crystals.     

New Hybrid Material: (C<Subscript>3</Subscript>H<Subscript>6</Subscript>N<Subscript>3</Subscript>)<Subscript>4</Subscript>Bi<Subscript>2</Subscript>Cl<Subscript>10</Subscript>. Synthesis,Structural Study and Spectroscopic Behavior

The structure of (C₃H₆N₃)₄Bi₂Cl₁₀ was determined by single crystal X-ray diffraction at room temperature. It crystallizes in the orthorhombic space group Pcmn, with a = 9.430 (1) Å, b = 17.426 (3) Å, c = 19.883(5) Å, V = 3267.3 (11) ų and Z = 4. The structure consists of discrete binuclear [Bi₂Cl₁₀]^4– anions and 3-aminopyrazolium cations. The crystal packing is governed by weak N–H···Cl hydrogen bonds, π–π and electrostatic Cl···Cl interactions. Infrared spectrum is used to gain more information on the title compound. An assignment of the observed vibration modes is reported. The crystal morphology is studied using the BFDH laws. The calculated HOMO and LUMO energies show that charge transfer occur within organic and inorganic molecules. The optical absorption of the zero-dimensional hybrid was also investigated.     

Synthesis,crystal structure,and biological properties of the complex [Co(DmgH)<Subscript>2</Subscript>(Seu)<Subscript>1.4</Subscript>(Se-Seu)<Subscript>0.5</Subscript>(Se<Subscript>2</Subscript>)<Subscript>0.1</Subscript>][BF<Subscript>4</Subscript>]

A new Co(III) dioxime complex with selenocarbamide was obtained by the reaction of Co(BF₄)₂ ? 6H₂O, DmgH₂, and Seu (DmgH2 = dimethylglyoxime, Seu = selenocarbamide). According to X-ray diffraction (CIF file CCDC no. 1485732), the product was an ionic coordination compound with unusual composition, [Co(DmgH)₂(Seu)_1.4(Se-Seu)_0.5(Se₂)_0.1][BF₄] (I). Apart from two monodeprotonated DmgH￣ molecules, the central atom coordinates neutral Seu, Se-Seu, and Se₂ molecules. Thus, the crystal contains the complex cations [Co(DmgH)₂(Seu)₂]⁺, [Co(DmgH)₂(Seu)(Se-Seu)]⁺, and [Co(DmgH)₂(Seu)(Se₂)]⁺. Each [BF₄]￣ anion is linked to the cations not only by electrostatic forces but also by intermolecular N–H···F hydrogen bonds (H-bonds). The complex cations are combined by intermolecular N–H···O H-bonds. The new coordination compound was found to possess biological activity. Treatment of the garlic (Allium sativum L.) foliage with an aqueous solution of I optimizes the content of selenium in the leaves and cloves and enhances the growth and plant productivity. The organs of treated plants are characterized by enhanced antioxidant protection owing to increasing activity of antioxidant enzymes and contents of proline and assimilation pigments, and decreasing lipid peroxidation.     

Phase formation in the Ag<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-MgMoO<Subscript>4</Subscript>-Al<Subscript>2</Subscript>(MoO<Subscript>4</Subscript>)<Subscript>3</Subscript> system

The subsolidus region of the Ag₂MoO₄-MgMoO₄-Al₂(MoO₄)₃ ternary salt system has been studied by X-ray phase analysis. The formation of new compounds Ag_{1 ? x} Mg_{1 ? x} Al_{1 + x} (MoO₄)₃ (0 ≤ x ≤ 0.4) and AgMg₃Al(MoO₄)₅ has been determined. The Ag_{1 ? x} Mg_{1 ? x} Al_{1 + x} (MoO₄)₃ variable-composition phase is related to the NASICON type structure (space group R \(\bar 3\) c). AgMg₃Al(MoO₄)₅ is isostructural to sodium magnesium indium molybdate of the same formula unit and crystallizes in triclinic system (space group P \(\bar 1\), Z = 2) with the following unit cell parameters: a = 9.295(7) Å, b = 17.619(2) Å, c = 6.8570(7) Å, α = 87.420(9)°, β = 101.109(9)°, γ = 91.847(9)°. The compounds Ag_{1 ? x} Mg_{1 ? x} Al_{1 + x} (MoO₄)₃ and AgMg₃Al(MoO₄)₅ are thermally stable up to 790 and 820°C, respectively.     

Synthesis and characterization of the [Ru<Subscript>3</Subscript>O(CH<Subscript>3</Subscript>COO)<Subscript>6</Subscript>(py)<Subscript>2</Subscript>(BPE)Ru(bpy)<Subscript>2</Subscript>Cl](PF<Subscript>6</Subscript>)<Subscript>2</Subscript> dimer

The polymetallic [Ru₃O(CH₃COO)₆(py)₂(BPE)Ru(bpy)₂Cl](PF₆)₂ complex (bpy = 2,2′-bipyridine, BPE = trans-1,2-bis(4-pyridil)ethylene and py = pyridine) was assembled by the combination of an electroactive [Ru₃O] moiety with a [Ru(bpy)₂(BPE)Cl] photoactive centre, and its structure was determined using positive ion electrospray (ESI-MS) and tandem mass (ESI-MS/MS) spectrometry. The [Ru₃O(CH₃COO)₆(py)₂(BPE)Ru(bpy)₂Cl]²⁺ doubly charged ion of m/z 732 was mass-selected and subject to 15 eV collision-induced dissociation, leading to a specific dissociation pattern, diagnostic of the complex structure. The electronic spectra display broad bands at 409, 491 and 692 nm ascribed to the [Ru(bpy)₂(BPE)] charge-transfer bands and to the [Ru₃O] internal cluster transitions. The cyclic voltammetry shows five reversible waves at −1.07 V, 0.13 V, 1.17 V, 2.91 V and −1.29 V (vs SHE) assigned to the [Ru₃O]^{−1/0/+1/+2/+3} and to the bpy^0/−1 redox processes; also a wave is observed at 0.96 V, assigned to the Ru^+2/+3 pair. Despite the conjugated BPE bridge, the electrochemical and spectroelectrochemical results indicate only a weak coupling through the π-system, and preliminary photophysical essays showed the compound decomposes under visible light irradiation.     

Preparation and X-ray diffraction study of phosphate sulfates M<Subscript>2</Subscript>MgTi(SO<Subscript>4</Subscript>)(PO<Subscript>4</Subscript>)<Subscript>2</Subscript>

Phosphate sulfates M₂MgTi(SO₄)(PO₄)₂ (M = alkali metal) prepared by the sol–gel technique with ethanol as salting-out agent were characterized by differential thermal analysis, electron probe microanalysis, and X-ray phase analysis. The crystal structure of the compounds synthesized (M = Na, K) was refined by powder X-ray diffraction. The phase stability of the phosphate sulfates under heating was examined.     

Synthesis and study of sodium triuranate Na<Subscript>2</Subscript>(UO<Subscript>2</Subscript>)<Subscript>3</Subscript>O<Subscript>3</Subscript>(OH)<Subscript>2</Subscript>

Sodium triuranate Na₂(UO₂)₃O₃(OH)₂ was synthesized by the reaction between aqueous uranyl acetate solution and aqueous sodium nitrate solution under hydrothermal conditions at 200°C. The composition and structure of the synthesized compound were determined, and its dehydration and thermal decomposition were studied, by chemical analysis, X-ray diffraction, IR spectroscopy, and thermal analysis.     

LaNi<Subscript>0.5</Subscript>Ti<Subscript>0.5</Subscript>O<Subscript>3</Subscript>/CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript>-based sensor for sensitive determination of paracetamol

A novel electrochemical sensor based on LaNi_0.5Ti_0.5O₃/CoFe₂O₄ nanoparticle-modified electrode (LNT–CFO/GCE) for sensitive determination of paracetamol (PAR) was presented. Experimental conditions such as the concentration of LNT–CFO, pH value, and applied potential were investigated. Under the optimum conditions, the electrochemical performances of LNT–CFO/GCE have been researched on the oxidation of PAR. The electrochemical behaviors of PAR on LNT–CFO/GCE were investigated by cyclic voltammetry. The results showed that LNT–CFO/GCE exhibited excellent promotion to the oxidation of PAR. The over-potential of PAR decreased significantly on the modified electrode compared with that on bare GCE. Furthermore, the sensor exhibits good reproducibility, stability, and selectivity in PAR determination. Linear response was obtained in the range of 0.5 to 901 μM with a detection limit of 0.19 μM for PAR.     

Crystal structures of Ti(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>P<Subscript>4</Subscript>O<Subscript>13</Subscript> and Sn(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>P<Subscript>4</Subscript>O<Subscript>13</Subscript>

The characteristics of crystal structures of the titanium(IV) diammonium (Ti(NH₄)₂P₄O₁₃) and tin(IV) diammonium (Sn(NH₄)₂P₄O₁₃) tetraphosphates, which are isostructural with similar silicon(IV) and germanium(IV) salts, have been obtained by the Rietveld method using X-ray powder diffraction data. The compounds crystallize in the triclinic system, space group P \(\overline 1 \), Z = 2, a = 15.0291(7) Å, b = 7.9236(4) Å, c = 5.0754(3) Å, α = 99.168(3)°, β = 97.059(3)°, γ = 83.459(3)° for Ti(NH₄)₂P₄O₁₃ and a = 15.1454(7) Å, b = 8.0103(5) Å, c = 5.1053(3) Å, α = 99.898(6)°, β = 96.806(3)°, γ = 83.881(4)° for Sn(NH₄)₂P₄O₁₃. The structure is refined in the isotropic approximation using the pseudo-Voigt function: R _p = 0.077, R _Bragg = 0.045, R _F = 0.057 for Ti(NH₄)₂P₄O₁₃; R _p = 0.082, R _Bragg = 0.044, R _F = 0.046 for Sn(NH₄)₂P₄O₁₃. The hydrogen atoms of the ammonium cations are placed in the calculated positions. A comparative analysis of the structures of the compounds of the M^IV(NH₄)₂P₄O₁₃ (M^IV = Si, Ge, Ti, Sn) series has been carried out.     

Supramolecular 2D structure of [Co(2-Me-Pyz)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

The complex [Co(2-Me-Pyz)₂(H₂O)₄](NO₃)₂ is synthesized and its structure is determined. The crystals are monoclinic: space group P2₁/n, a = 10.685(2) Å, b = 6.837(1), c = 12.515(3) Å, β = 91.84(3)°, V = 913.8(3) ų, ρ_calcd = 1.042 g/cm ³, Z = 2. The Co²⁺ ion (in the inversion center) is coordinated at the vertices of the distorted octahedron by two nitrogen atoms of methylpyrazine and four oxygen atoms of the water molecules (Co(1)–N(1) 2.180(3), average Co(1)–O(w) 2.079(3) Å, angles at the Co atom 87.9(1)–92.1(1)°). Supramolecular pseudometallocycles are formed in the structure through the O(w)–H…N(1) hydrogen bonds between the coordinated H₂O molecules and the terminal nitrogen atoms of the 2-methylpyrazine molecules. Their interaction results in the formation of supramolecular layers joined by the NO₃ groups into a three-dimensional framework.