Molecular structure and hydrogen bonding of 4-dimethylaminopyridinioacetate in its crystalline dihydrate and hydrochloride trihydrate,L·2H2O and [L2H]Cl·3H2O (L=p-Me2NC5H4N+CH2CO2 −)

The crystalline dihydrate and hydrochloride trihydrate of a new betaine, namely, L·2H₂O (1) and [L₂H]Cl·3H₂O(2) (L=p-Me₂NC₅H₄N⁺CH₂CO₂), have been synthesized and characterized by X-ray crystallography. Molecule L in compound1 [space groupPbcn, witha=15.732(3),b=7.894(2),c=18.304(4) Å, andZ=8] possesses approximateC _s symmetry. The formation of hydrogen bonds by water molecules bridging neighboring carboxy oxygen atoms leads to an infinite two-dimensional network composed of a packing of two different kinds of 12-membered rings. In compound2 [space group PT witha=7.341(2),b=9.543(2),c=17.010(4) Å, =82.43(2)°, =80.34(2)°, =74.05(2)°, andZ=2], the carboxylate groups of a pair of betaine molecules are bridged by a proton to form a dimeric cation L₂H⁺ with a very strong asymmetric hydrogen bond of length 2.464(7) Å. The crystal structure features a hydrogen-bonded corrugated ribbon comprising an alternate arrangement of edge-sharing centrosymmetric (H₂O)₄(Cl^–)₂ and (H₂O)₄ rings running parallel to thea axis.     

Synthesis and X-ray structure of [(H3O)(C14H20O5)2][Me2NH2]2 [PMo12O40] · 2C14H20O5 (C14H20O5 = benzo-15-crown-5; Me2NH = dimethylamine)

[(H₃O)(C₁₄H₂₀O₅)₂][Me₂NH₂]₂ [PMo₁₂O₄₀] · 2C₁₄H₂₀O₅ 1 was synthesized from benzo-15-crown-5 and H₃PMo₁₂O₄₀·24H₂O in N,N-dimethylformamide for the first time. 1 crystallizes in the monoclinic space group C2/c with a = 18.583(4), b = 25.510(5), c = 19.904(4) Å, = 94.66(3)° D _c = 2.124 mg/m³ for Z = 4. Refinement based on 7358 observed reflections led to a R1(wR2) = 0.0378(0.0761). The complex cation, [(H₃O)(C₁₄H₂₀O₅)₂]⁺, exhibits a sandwich structure by hydrogen-bonding in the mean distance of 2.955 Å. The anion, PMo₁₂O₄₀ ^3–, is a -Keggin structure.     

BaBPO5和(H3O)Zn(H2O)2BP2O8·H2O的低温溶剂热合成及表征

以乙醇为溶剂,在低温条件下合成出了两种手性硼磷酸盐化合物BaBPO5(1)(T=120℃,t=5d)和(H3O)Zn(H2O)2BP2O8·H2O (2)(T=80℃,t=5d).XRD单晶衍射仪测定了化合物的结构,结果表明:(1)属三方晶系,P3221空间群,a=b=7.1162(3)(A),c=6.9979(6),(A)=3,该晶体含有一维线性链状阴离子结构;(2)属六方晶系,P6122空间群,a=b =9.513(2)(A),c=15.906(8),(A)=6.该晶体具有三维骨架结构.实验结果表明使用乙醇作溶剂可以极大降低硼磷酸盐的合成温度,进而有助于获得手性硼磷酸盐化合物,这为手性硼磷酸盐的合成提供了一种新思路.     

Crystal structure of NH3(CH2)2NH3BiCl5·2H2O

The ethylenediammonium pentachlorobismuthate(III) dihydrate salt is monoclinic with the following unit cell dimensions: a = 10.902(8)Å, b = 7.926(6)Å, c = 15.199(6)Å, = 96.40(1)°, space group P2₁/n with Z = 4. The structure shows a layer arrangement parallel to the axis: planes of the [Bi₂Cl₁₀]^4– bioctahedra alternate with planes of [NH₃(CH₂)₂NH₃]²⁺ dications. The [Bi₂Cl₁₀]^4– bioctahedra are connected through O(W)–H··· Cl hydrogen bonds, so that infinite unidimensional chains of composition [Bi₂Cl₁₀(H₂O)₂] _n ^4n– are formed in the structure parallel to the axis. These chains are themselves interconnected by means of the N–H···Cl bonds originating from the [NH₃(CH₂)₂NH₃]²⁺ entities, forming a three-dimensional network.     

Luminescence and energy transfer in Dy3+/Tb3+ co-doped CaO–Al2O3–B2O3–RE2O3 glass

The new calcium aluminoborate glasses with the composition of CaO–Al₂O₃–B₂O₃–RE₂O₃ (RE = Dy and Tb) were synthesized and the luminescence of Dy³⁺ and Tb³⁺ was investigated. The results show that the emission intensity of Tb³⁺ ion was enhanced when introducing Dy³⁺ ion into CaO–Al₂O₃–B₂O₃–Tb₂O₃ glass due to the energy transfer processes between Dy³⁺ and Tb³⁺. The energy transfer efficiencies, transfer probabilities as well as donor–acceptor critical distances were also calculated. The energy transfer mechanism between Dy³⁺ and Tb³⁺ ions is electric dipole–dipole interaction, which can be concluded by both fluorescence decay and emission intensity ratio varieties.     

Ce3+∶GdLu2Al5O12/Al2O3共晶微结构及其发光性能

稀土共晶闪烁体是通过定向凝固晶体生长技术,将具有不同折射率的两相制备成具有射线探测功能的共晶材料,其中含有激活离子的闪烁体相的折射率高于基质相。在高能射线辐照下,闪烁体相将入射高能射线转换成荧光,然后,荧光在闪烁体相和基底相的界面以全反射的形式实现定向输出,从而有效提高辐射探测成像的空间分辨率。本工作采用微下降法成功生长得到φ3 mm×117.0 mm 的1.0%(原子数分数)Ce∶GdLu₂Al₅O₁₂/Al₂O₃闪烁共晶样品。通过切割抛光加工得到φ3 mm×2.0 mm的共晶薄片,并将该共晶薄片进行微观结构、能谱分析和荧光性能等表征和测试,结果表明所得到的共晶样品由Ce∶GdLuAG和Al₂O₃两晶相构成,微观结构呈现出“中国结”结构,并在生长方向呈现出一定的有序排列。荧光光谱测试表明该共晶材料存在Gd³⁺-Ce³⁺间的能量传递,具有典型的Ce³⁺辐射跃迁,其中双宽峰发射峰最强位于560 nm。此外,根据生长速率对共晶样品发射峰强、峰位以及荧光寿命影响,优化出最佳下拉生长速率为4.0 mm/min。     

Structure and properties of NaPO3–ZnO–Nb2O5–Al2O3 glasses

In an effort to design low-melting, durable, transparent glasses, two series of glasses have been prepared in the NaPO₃–ZnO–Nb₂O₅–Al₂O₃ system with ZnO/Nb₂O₅ ratio of 2 and 1. The addition of ZnO and Nb₂O₅ to the sodium aluminophosphate matrix yields a linear increase of properties such as glass transition temperature, density, refractive index and elastic moduli. The chemical durability is also significantly, but nonlinearly, improved. The glass with the highest niobium concentration, 55NaPO₃–20ZnO–20Nb₂O₅–5Al₂O₃ was found to have a dissolution rate of 4.5 × 10^? 8 g cm^? 2 min^? 1, comparable to window glass. Structural models of the glasses were developed using Raman spectroscopy and nuclear magnetic resonance spectroscopy, and the models were correlated with the compositional dependence of the properties.     

Synthesis and structure of (NH4)3[UO2(C3H2O4)2(NCS)] · 2H2O

Malonate-thiocyanate complex (NH₄)₃[UO₂(C₃H₂O₄)₂(NCS)] · 2H₂O is synthesized and studied by X-ray diffraction. The compound crystallizes in the monoclinic system: a = 13.9983(4) Å, b = 8.1947(2) Å, c = 16.4678(4) Å, β = 100.846(1)°, space group Cc, Z = 4, and R = 0.0158. The main structural units of the crystal are mononuclear [UO₂(C₃H₂O₄)₂(NCS)]^3? groups belonging to the AB ₂ ⁰¹ M ₁ crystal chemical group of uranyl complexes (A = UO ₂ ²⁺ , B ⁰¹ = C₃H₂O ₄ ^2? , M ¹ = NCS^?). Discrete uranium-containing groups are connected by electrostatic interactions with ammonium ions and by hydrogen bonds. Some specific structural features of crystals containing [UO₂(L)₂(NCS)]^3? complexes, where L is the oxalate or malonate ion, are discussed.     

Crystal and molecular structure of complex compound [Fe3O(CH3COO)6(H2O)3]2[ZnCl4] ⋅ 2H2O

The X-ray crystal structure of trinuclear iron acetate [Fe₃O(CH₃COO)₆(H₂O)₃]₂ [ZnCl₄] ? 2H₂O was determined. The crystal has a ionic structure. It is monoclinic, a = 25.363(7), b = 14.533(4), c = 15.692(4) Å, β = 103.11(2)°, space group _C2/c, and R = 0.0685. The structure of the cationic complex [Fe₃O(CH₃COO)₆(H₂O)₃]⁺ is typical of trinuclear iron(III) compounds containing a μ₃-O bridge: the iron atoms are situated at the vertices of an almost equilateral triangle with the O atom at the center. Each Fe atom is coordinated by four O atoms of bridging carboxy groups, the μ₃-bridging O atom, and the water molecule in the trans position to the latter O atom. Mössbauer spectroscopy evidence indicates the high-spin state (_S = 5/2) of the iron(III) ions.     

Crystal and molecular structure of 7-hydroxyflavone monohydrate, C14H10O3·H2O

The X-ray crystal structure of 7-hydroxyflavone monohydrate, C₁₄H₁₀O₃ · H₂O, is determined. The compound crystallizes in the monoclinic space group, P2₁/n with a = 3.801(3), b = 19.665(4), c = 16. 039(6), = 93.69(3)°, and = 0.68 mm^–1 for Z = 4. The phenyl ring of the flavone moiety is rotated 18.6(1)° out of the penzopyran plane, which is a typical value for flavones. In the crystal lattice, there are wide channels which are lined mainly by C–H groups. The water molecules enclosed in these channels are severely disordered.     

Crystal and molecular structures of potassium cobalt hydrogen phthalate K2[Co(H2O)6](C8H5O4)4 ⋅ 4H2O and mechanism of Co2+ impurity trapping in KAP crystals

The single-crystal X-ray diffraction analysis of K₂[Co(H₂O)₆](C₈H₅O₄)₄ ? 4H₂O has been carried out. The K₂[Co(H₂O)₆](C₈H₅O₄)₄ ? 4H₂O single crystals are obtained in attempting to grow the KAP crystals with the maximum possible content of Co²⁺ impurity cations. The crystals are isostructural to the earlier-studied similar crystals with Ni(II). The structure is formed by double layers of biphthalate anions and the Co²⁺ and K⁺ cations in between. The Co²⁺ cations are coordinated only by water molecules, whereas the coordination of the K⁺ cations involves both the biphthalate anions and water molecules. A detailed crystal chemical analysis, together with the data on the growth kinetics of KAP crystals in the presence of Co²⁺ and the mass-spectrometric data obtained earlier for the KAP crystals, leads to the conclusion that the Co²⁺ impurity cations should be located in the form of the [Co(H₂O)₆]²⁺ cationic complexes in the interblock layers of the KAP crystals.     

Crystal structures of acid ethylenediaminetetraacetates [Cd(H2 Edta)(H2O)] · 2H2O and [Mn(H2O)4][Mn(HEdta)(H2O)]2 · 4H2O

The crystal structures of [Cd(H₂ Edta)(H₂O)] · 2H₂O (I) and [Mn(H₂O)₄][Mn(HEdta)(H₂O)]₂ · 4H₂O (II) are studied by X-ray diffraction [R ₁ = 0.0209 (0.0272), wR ₂ = 0.0571 (0.0730) for 2551 (4025) reflections with I > 2σ(I) in I (II), respectively]. Structure I contains mononuclear [Cd(H₂ Edta)(H₂O)] complexes with the C ₂ symmetry, and structure II contains centrosymmetric trinuclear [Mn(H₂O)₄][Mn(HEdta)(H₂O)]₂ complexes. In I and II, the protonated ligands are hexadentate (2N + 4O), and the water molecule increases the coordination number of the metal atom to seven. The acid protons participate in short intermolecular hydrogen bonds, which are symmetric in II and asymmetric in I.     

Glass forming region and physical properties in the system P2O5-Na2O–Fe2O3

The glass forming region of the system P₂O₅–Na₂O–Fe₂O₃ was determined, using phosphate salts as precursor materials. The glasses were produced in non-wetting gold/platinum crucibles in order to avoid contamination. Glass formation was confirmed using XRD and the final composition determined using EDX. The glass forming region was found to be relatively short at 50% P₂O₅ content in comparison to both lower and higher P₂O₅ content. As expected, the inclusion of Fe₂O₃ had a significant effect on both glass transition temperature and density with a peak seen at around 30 mol% Fe₂O₃. This coincides with previously reported abrupt structural changes in the glass. The inclusion of Na₂O has little effect on the glass transition temperature but causes a small increase in density.     

Crystal structure and hydrogen-bonding system of cholic acid hemihydrate,C24H40O5·1/2H2O

Crystals of the hemihydrate of this bile acid are hexagonal, space groupP6₅22, a=b=13.736(8)Å,c=85.06(6)Å,V=13,899ų. The asymmetric unit contains two independent steroid molecules and one water molecule, the latter disordered over two nonequivalent positions.Z=12[2(C₂₄H₄₀O₅)·1(H₂O)],F(000)=5496. Structure solution by direct methods; refinement by least-squares, toR=0.072. The complex hydrogen-bond system comprises: (a) three standard ordered O-HO hydrogen-bonds; (b) what is probably a symmetrically hydrogen-bonded carboxylic acid dimer, with a twofold rotation axisin the plane of the two carboxyl groups; (c) helical hydrogen-bonding chains about each 6₅ axis, disordered over four possible arrangements. In these helical chains, the six independent hydrogen-bonds can as a group be in either of two systems of nearly equivalent flip-flop arrangements: O-HO OH-O. Each helical system includes water, which can occupy either of two sites; thus, there is further disorder involving two sets of nonequivalent hydrogen-bonds with water as donor and acceptor. Many aggregation features here differ markedly from those in the crystal structures of either anhydrous cholic acid or cholic acid monohydrate.     

Preparation,crystallization behavior and magnetic properties of nanoparticles magnetic glass–ceramics in the systems Fe2O3 CoO MnO2, Fe2O3 NiO MoO3 and Fe2O3 CoO V2O5

Ferrimagnetic glass–ceramics were prepared in the systems Fe₂O₃ CoO MnO₂ (S1), Fe₂O₃ NiO MoO₃ (S2) and Fe₂O₃ CoO V₂O₅ (S3). Small amount of H₃BO₄ was added to make the melting process easier. The samples were characterized using DTA, XRD, TEM and EDX. Sequence of crystallization was studied by applying heat-treatment at 800 and 1000 °C for 4 h. CoFe₂O₄ with crystallite sizes of ≈ 14–20 nm was successfully prepared beside FeCoOBO₃ and Co₃BO₅ in S1. NiMoO₄, (FeNi₂)O₂(BO₃) and NiO with crystallite size ≈ 56–79 nm were crystallized in S2. CoFe₂O₄, FeCoOBO₃ and Co₃BO₅ with crystallite size ≈ 6–8 nm were crystallized in S3. Magnetic hysteresis cycles were analyzed with a maximum applied field of 20 kOe at room temperature. From the obtained hysteresis loops Ms records higher values for S1 and S3 and lower value for S2, while coercivity reach maximum for S2. The variable, magnetic, data range gives a wide range for different applications.     

R2O-RO-SiO2-Al2O3-Fe2O3-P2O5系分相釉的研究

针对铁红分相釉的配方特点,采用L8(4 ×24)正交实验研究了钠长石、牛骨灰、滑石、方解石、石英加入量对R2O-RO-SiO2-Al2O3-Fe2O3-P2O5系统分相釉釉面效果的影响,采用扫描电子显微镜(SEM)和能谱分析(EDS)对釉层的微观结构进行了表征.研究发现:牛骨灰对釉面是否出现“柿红”效果影响最显著,而方解石影响最不明显.Si/P摩尔比对铁红色釉面的产生起关键作用,当Si/P摩尔比小于2O,出现铁红釉面效果的概率极高.随着滑石加入量从9份变化到18份,出现铁红色釉面的趋势反而降低.经SEM和EDS分析发现,“柿红色”、“酒红色”釉面效果的产生很大程度上是由于釉层液液分相促进Fe2O3富集或偏析造成,且特别容易在高钠、低镁、低铝处聚集,最终连成雪花状结晶.     

Hydrothermal Synthesis and Characterization of a New Strandberg-type Diphosphopentamolybdate (C6N3H18)2[P2Mo5O23] · 6H2O

Crystallography Reports - An inorganic-organic hybrid material formulated as (C6N3H18)2[P2Mo5O23] · 6H2O, has been hydrothermally synthesized and characterized by single crystal X-ray...     

Influence of thermal and thermoelectric treatments on structure and electric properties of B2O3–Li2O–Nb2O5 glasses

A transparent glass with the composition 60B₂O₃–30Li₂O–10Nb₂O₅ (mol%) was prepared by the melt quenching technique. The glass was heat-treated with and without the application of an external electric field. The as-prepared sample was heat-treated (HT) at 450, 500 and 550 °C and thermoelectric treated (TET) at 500 °C. The following electric fields were used: 50 kV/m and 100 kV/m. Differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, dc and ac conductivity, as a function of temperature, were used to investigate the glass and glass-ceramics properties. LiNbO₃ crystals were detected, by XRD, in the 500 °C HT, 550 °C HT and 500 °C TET samples. The presence of an external electric field, during the heat-treatment process, improves the formation of LiNbO₃ nanocrystals at lower temperatures. However, in the 550 °C HT and in the TET samples, Li₂B₄O₇ was also detected. The value of the σ_dc decreases with the rise of the applied field, during the heat-treatment. This behavior can indicate an increase in the fraction of the LiNbO₃ crystallites present in these glass samples. The dc and ac conduction processes show dependence on the number of the ions inserted in the glass as network modifiers.The Raman analysis suggests that the niobium ions are, probably, inserted in the glass matrix as network formers.These results reflect the decisive effect of temperature and electric field applied during the thermoelectric treatment in the structure and electric properties of glass-ceramics.     

BaTiO3-Nb2O5-Fe2O3陶瓷介电性能的研究

利用传统方法制备了BaTiO3-Nb2O5-Fe2O3(BTNF)陶瓷,采用X射线衍射仪、电容测试仪、电滞回线测量仪等测试手段研究了不同添加剂(Fe2O3、Co2O3、Nb2O5)对陶瓷晶体结构、介电性能及铁电性的影响.结果表明:Nb2O5是施主掺杂,易引起晶格畸变,使四方率增大;而Fe2O3为受主掺杂,其可提高氧空位浓度,促进BaTiO3陶瓷晶粒生长.同时掺杂Fe2O3、Nb2O5时,可以相互补偿.当Fe2O3浓度约为0.15;摩尔分数,Nb2O5浓度为0.79;摩尔分数时,陶瓷的介电常数达到4443,温度特性≤±10;,可以满足Y5P瓷料的要求.