Synthesis and crystal structure of [nBu4N][Er(pic)4] · 5.5H2O: a new infrared emitter

The new erbium(III) complex of picolinic acid (Hpic), [ⁿBu₄N][Er(pic)₄] · 5.5H₂O, was synthesized and the crystal structure determined by single-crystal X-ray diffraction. The compound was further characterized using IR, Raman, ¹H NMR and elemental analysis. The picolinate ligands (pic⁻) are coordinated through N,O-chelation to the erbium cations, as shown by X-ray diffraction and spectroscopic results, leading to an eight coordinate complex. Photoluminescence measurements were performed for this compound which exhibits infrared emission.     

[HTeV9O28]4−: A new vanadotellurate with decavanadate structure

The first vanadotellurate, [HTeV₉O₂₈]⁴⁻, has been synthesized and structurally characterized. The ⁵¹V and ¹H NMR revealed that the proton stays on the surface of the molecular oxide anion even in solution.

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A novel polyoxometalate-based metal-organic compound constructed from an unprecedented [Ag8(Hpyttz)4(H2pyttz)2] cluster and an in-situ [VW12O40]3 − anion

A novel polyoxometalate (POM)-based metal-organic compound constructed from a multinuclear Ag^I cluster and Keggin-type [VW₁₂O₄₀]^3 − anion, [Ag₄(Hpyttz)₂(H₂pyttz)][HVW₁₂O₄₀]·3H₂O (1) (H₂pyttz = 5′-(pyridin-4-yl)-1H,2′H-3,3′-bi(1,2,4-triazole), was hydrothermally synthesized and characterized by IR spectroscopy, TG analysis, powder and single-crystal X-ray diffraction. In compound 1, [VW₁₂O₄₀]^3 − (VW₁₂) was in-situ transformed from [SiW₁₂O₄₀]^4 − anion. Eight Ag^I ions were connected by six Hpyttz/H₂pyttz ligands with three coordination modes forming an unprecedented [Ag₈(Hpyttz)₄(H₂pyttz)₂] cluster, which connected with six VW₁₂ anions to construct a 2-D double-layer (3,6)-connected network with {4³}₂{4⁶.6⁶.8³} topology. Moreover, the photocatalytic activity of 1 has been investigated.     

Calix[4]arene–carbazole-containing polymers: Synthesis and properties

New highly fluorescent calix[4]arene-containing phenylene-alt-ethynylene-3,6- and 2,7-carbazolylene polymers (CALIX-PPE-CBZs) have been synthesized for the first time and their photophysical properties evaluated. Both polymers were obtained in good isolated yields (70–84%), having M_w ranging from 7660–26,700 g mol⁻¹. It was found that the diethynyl substitution (3,6- or 2,7-) pattern on the carbazole monomers markedly influences the degree of polymerization. The amorphous yellow polymers are freely soluble in several nonprotic organic solvents and have excellent film forming abilities. TG/DSC analysis evidences similar thermal behaviors for both polymers despite their quite different molecular weight distributions and main-chain connectivities (T_g in the range 83–95 °C and decomposition onsets around 270 °C).The different conjugation lengths attained by the two polymers dictates much of their photophysical properties. Thus, whereas the fully conjugated CALIX-PPE-2,7-CBZ has its emission maximum at 430 nm (E_g = 2.84 eV; Φ_F = 0.62, CHCl₃), the 3,6-linked counterpart (CALIX-PPE-3,6-CBZ) fluoresces at 403 nm with a significant lower quantum yield (E_g = 3.06 eV; Φ_F = 0.31, CHCl₃). The optical properties of both polymers are predominantly governed by the intrachain electronic properties of the conjugated backbones owing to the presence of calix[4]arenes along the polymer chain which disfavor significant interchain interactions, either in fluid- or solid-state.     

Synthesis,crystal structure and luminescent properties of new tris-β-diketonate Eu(III) complex with thiadiazolophenanthroline derivative ligand

Herein we describe the synthesis, characterization and spectroscopic properties of the complex tris-(thenoyltrifluoroacetonate)([1, 2, 5]thiadiazolo[3, 4-f][1,10]phenanthroline) europium(III) acetonitrile solvate, [Eu(TTA)₃ TDPHEN] 1.5CH₃CN, where TTA = 2-thenoyl trifluoroacetone and TDPHEN = [1, 2, 5]thiadiazolo[3, 4-f][1, 10] phenanthroline. X-ray crystallography reveals that it is an eight-coordinate Eu(III) complex containing three β-diketonate chelates and one N,N′-bidentate ligand, [1, 2, 5] thiadiazolo[3, 4-f][1, 10] phenanthroline. The excitation at 340 nm of the europium complex in a solution of acetonitrile, and at room-temperature, showed the typical Eu(III) red emission as a sharp band at 611 nm, characteristic of Eu(III) due to the transition ⁵D₀ → ⁷F₂. This complex also showed red emission in the solid state phase (λ_em = 612 nm).     

Absorption properties of an inverted cucurbit[7]uril-based porous coordination polymer induced by [ZnCl4]2 − anions

Coordination of an inverted cucurbit[7]uril (iQ[7]) with a series of alkali cations (A⁺), revealed that iQ[7] can interact with potassium to form iQ[7]-K⁺-based porous coordination polymer in the presence of [ZnCl₄]^2 − anions as a structure directing agent. Unexpectedly, isothermal titration calorimetry revealed no obvious interaction of iQ[7] with any A⁺ cation. Moreover, the iQ[7]-K⁺-based porous coordination polymer showed selective sorption of polar volatile organics, which may have potential applications for molecular sieves, sensors, and absorption and separation processes.     

pH-dependent assembly of 1D–2D structures based on both {V10O28} and [NiMo6O24H6]4 − units: Synthesis,structure and magnetic properties

Two novel complexes [H₂N(CH₂CH₂)₂O]₄[Na(H₂O)₂{O(CH₂CH₂)₂NH₂}]₂[Na(H₂O)₄]₂[V₁₀O₂₈][NiMo₆O₂₄H₆]·8H₂O (1) and [H₂N(CH₂CH₂)₂O]₆[Na(H₂O)₃]₂[V₁₀O₂₈H₂][NiMo₆O₂₄H₆]·4H₂O (2) containing both isopolyvanadate {V₁₀O₂₈} and [NiMo₆O₂₄H₆]^4 − units have been synthesized and structurally characterized for the first time, showing that the pH value of the reaction plays a key role in structure control of self-assembled processes. Compound 1 exhibits a novel one-dimensional (1-D) chain-like structure consisting of Anderson-type [NiMo₆O₂₄H₆]^4 − and isopolyvanadate [V₁₀O₂₈]^6 − anions linked by Na⁺ ions. In compound 2 with the lower pH value, [NiMo₆O₂₄H₆]^4 − and [V₁₀O₂₈H₂]^4 − anions are bridged by [Na₂O₁₀] units to form the 2D extended layer. The magnetic properties of 1 and 2 are presented.     

A new polyanion with Dawson-like constitution: [H2SeW18O60]6 −

A new tungstoselenite, [H₂SeW₁₈O₆₀]^6 −, was isolated under acidic medium conditions (pH = 1.7)with the monoprotonated ethylamine as cation. It represents the first example of Se-containing polyoxometalate with unusual Dawson-like construction and has fully been characterized both in solid state and in solution. The high-resolution ESI-MS confirmed that the polyanion at least contains two protons and its proton number can be up to six in solution.     

Synthesis and negative thermal expansion properties of solid solutions Yb2−xLaxW3O12 (0 ≤ x ≤ 2)

A new series of rare earth solid solutions Yb_2?xLa_xW₃O₁₂ were successfully synthesized by the solid-state method. Effects of substituted ion lanthanum on the microstructures and thermal expansion properties in the resulting Yb_2?xLa_xW₃O₁₂ ceramics were investigated by X-ray diffraction (XRD), thermogravimetric analyzer (TGA), field emission scanning electron microscope (FESEM) and thermal mechanical analyzer (TMA). Results indicate that the structural phase transition of the Yb_2?xLa_xW₃O₁₂ changes from orthorhombic to monoclinic with increasing substituted content of lanthanum. The pure phases can form in the composition range of 0 ≤ x < 0.5 with orthorhombic structure and 1.5 < x ≤ 2 with monoclinic one. High lanthanum content leads to a low hygroscopicity of Yb_2?xLa_xW₃O₁₂. Negative thermal coefficients of the Yb_2?xLa_xW₃O₁₂ (0 ≤ x ≤ 2) also vary from ?7.78 × 10^?6 K^?1 to 2.06 × 10^?6 K^?1 with increasing substituted content of lanthanum.     

A [Cu4I] cluster based metal-organic framework to detect F− ions

A new metal-organic framework, namely [Cu₄I(TIPE)₃]^.3I (1) (TIPE = tetra(3-imidazoylphenyl)ethylene), has been synthesized in the presence of sulfosalicylic acid under hydrothermal condition. Single-crystal X-ray diffraction shows that compound 1 exhibits a 2-nodal (4, 12)-connected interpenetrating network. Its luminescent property has been investigated at room temperature. Moreover, it has been used to detect halogen ions, and the experimental results show that it can selectively sense F⁻ ions through fluorescence quenching. The detection limit towards F⁻ ions is calculated to be 2.11 × 10^− 6 mol/L.     

[P2V3W15O62]9 − cluster based covalent polyoxometalate-organic hybrid: Synthesis,structure, self-assembly and in vitro antioxidant activities

A new [P₂V₃W₁₅O₆₂]^9 − cluster based covalent polyoxometalate-organic hybrid (P1) containing a naphthol-amide-Tris derivative has been synthesized and characterized using standard analytical and spectroscopic techniques including single crystal X-ray diffraction analyses. P1 exhibits interesting self-assembly behaviour leading to the generation of ~ 200 nm spherical aggregates in solutions as revealed by DLS and TEM analyses. Standard in vitro experiments revealed that P1 is capable of exhibiting moderate antioxidant properties under standard experimental conditions.     

Three-dimensional 3d–4f heterometallic coordination polymer containing Sm2Mn4 clusters: Synthesis,crystal structure and properties

Heterometallic coordination polymers of the form {[SmMn₂(imdc)₂(OAc)(H₂O)]·2H₂O}_n (1) (H₃imdc = 4,5-imidazoledicarboxylic acid, HOAc = acetic acid) were hydrothermally synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The results reveal that 1 has a three-dimensional framework containing Sm₂Mn₄ clusters. The luminescence and magnetic properties of 1 were also investigated.     

First-principles calculation of mechanical properties and electronic structures of W4Co4−nXnB4 (X = V,Mn, Fe,Ni; n = 0,1)

The first-principles calculation is performed to explore the mechanical properties and electronic structures of transition elements X (X = V, Mn, Fe, Ni) doped WCoB (tungsten cobalt boron), which has shown high oxidation resistance and melting point under high pressure. The energy analysis indicates that the high pressure leads to the lower lattice constants and less stable structures. The deviation of cohesive energy and formation enthalpy between doped and undoped structures indicates that W₄Co₃FeB₄ and W₄Co₃NiB₄ have similar stability. The high pressure contributes to the increasing of elastic, shear, and bulk moduli, which indicates the increase of covalence. The increase of Poisson's ratio, B/G ratio, and anisotropy index A^U indicates the higher ductility and higher anisotropy under high pressure. Based on bulk modulus and shear modulus, the hardness of W₄Co₄B₄, W₄Co₃FeB₄, and W₄Co₃NiB₄ increases under high pressure, which consists of the variation of electronic structures. The density of states (DOS) and partial DOS analysis indicate that the high pressure leads to lower density around Fermi level and higher hybridization. W₄Co₄B₄, W₄Co₃FeB₄, and W₄Co₃NiB₄ show similar variation of mechanical properties, which is determined by the similar atom properties of Co, Fe, and Ni. Similarly, W₄Co₃VB₄ and W₄Co₃MnB₄ also imply similar variation of mechanical properties and electronic structures.     

Synthesis,characterization and catalytic properties of La2−x Sr x NiO4−δ

Various compositionsx in the catalyst system La_2–x Sr _x NiO_4– have been prepared by conventional techniques and characterized by X-ray powder diffraction, electron microscopy and BET surface measurements. The catalytic properties of these catalysts have been tested in the propylene oxidation reaction. The catalytic activity can be correlated with the oxygen content and with the strontium substitution.     

Synthesis,structure of a coordination polymer: {Na2[Zn(C2O4)1.5H2PO4] · 2H2O}n

A phosphatooxalate compound {Na₂[Zn(C₂O₄)_1.5H₂PO₄] · 2H₂O}_n 1 was synthesized under hydrothermal condition and characterized by single-crystal X-ray diffraction, IR spectroscopy, thermal gravimetric analysis (TGA) and fluorescent spectroscopy. X-ray single-crystal analysis revealed that its structure was a new mixed inorganic–organic ligand supramolecular framework building up through multilayer assembly.     

Crystal structure,mixture behavior,and microwave dielectric properties of novel temperature stable (1 − x)MgMoO4 − xTiO2 composite ceramics

Novel temperature stable MgMoO₄–TiO₂ microwave dielectric ceramics were prepared by a solid state reaction process at low temperature (950 °C). As TiO₂ content increases, the relative permittivity increases while the Q × f value decreases, and the variation mechanisms are proposed, respectively. The temperature coefficient of resonant frequency (τ_f) shifts to the positive direction as TiO₂ is added. The mixture mechanisms of τ_f value for two-phase composite materials are supposed. A near-zero τ_f value (3.2 ppm/°C) is obtained when x = 0.3, with ε_r = 9.13 ± 0.03 and Q × f = 11,990 GHz. The 0.7MgMoO₄–0.3TiO₂ composites are considered to be appropriate as a low temperature co-fired ceramic material for microwave wireless communication applications.     

Hydrothermal synthesis,structure and properties of two new phosphomolybdates based on Strandberg-type {P2Mo5O23}6 − building units

Two inorganic–organic hybrid compounds based on Strandberg-type phosphomolybdates (abbreviated as {P₂Mo₅O₂₃}^6 −) complexes [H₃O]₂[Cu₂(Pyim)₂(H₂O)₃][P₂Mo₅O₂₃] · 6H₂O (1) and [Cu₃(Pyim)₃(H₂O)₄][P₂Mo₅O₂₃] · 7H₂O (2) were successfully synthesized at different pH values under hydrothermal conditions. Both 1 and 2 are based on the {P₂Mo₅O₂₃}^6 − clusters connected by copper complexes to generate one dimensional chain. The magnetic analyses of compounds 1 and 2 indicate antiferromagnetic interactions between copper ions.