X-ray crystal structure of 2-styrylpyridine

We have crystallized the 2-styrylpyridine from the condensation reaction between the 2-methylpyridine with benzaldehyde in the formation of the model compound 2-styrylpyridine. The X-ray structure and NMR are currently reported. The main features of the structure is that is shows a localization of the double bonds rather than a delocalization of π electrons in an aromatic fashion.     

Unexpected crystallization and X-ray crystal structure of racemic 1-phenyl-2-(4-pyridyl)ethanol intermediate

We have isolated, by crystallization, the intermediate, 1-phenyl-2-(4-pyridyl)ethanol, from the condensation reaction of 4-methylpyridine with benzaldehyde in which the aim was to obtain the model compound 4-styrylpyridine in absence of a condensing agent. Single crystal X-ray analysis shows the formation of an intermolecular hydrogen bond O–H···N between the nitrogen atom of a pyridine group and the oxygen atom of the OH of the neighboring molecule, which helps to stabilize the crystal structure. Crystal structure determination clearly revealed that the solid is chiral and racemic, as expected. The title compound crystallizes in an orthorhombic system with a space group Pna2₁ with two pairs of R and S enantiomers in each crystal cell (a = 15.591(1) Å, b = 12.691(1) Å, and c = 5.589(1) Å). Spectroscopic NMR data gave evidence that the isolated compound is actually the alcohol just before the dehydration process that yields the double bond of the 4-styrylpyridine.     

Crystal structure of 2,6-distyrylpyridine

We have crystallized the 2,6-distyrylpyridine compound from the condensation reaction of the 2,6-dimethylpyridine with benzaldehyde (at 135°C) to obtain a model compound having three rings joined with two double bonds in order to understand the structure of poly(2,6-styrylpyridine) and poly(2,6-pyridinediylvinylene) and their formation mechanism. The X-ray structure shows that the title compound belongs to the trigonal crystal system, space group P3², and with unit cell dimensions a = 15.5637 (12) Å, c = 5.7852 (13) Å. From the molecular structure it was clear that the substituents on double bonds were in the trans position, which was in agreement to the IR and ¹H NMR results. The molecule is planar and forms stacks in the crystal. The molecular structure of 2,6-distyrylpyridine has two trans double bonds between the rings and therefore it can be in three nonequivalent conformations. The preferred conformation showed by X-ray crystallography can be the result of weak steric interactions between the double bond trans hydrogens and the nearby hydrogens of the phenyl or pyridyl groups. The crystal structure, and IR and ¹H NMR results are currently reported.     

The Effect of Annealing Temperature on Electrical Properties of SrBi2Ta2O9/Insulators/Si(MFIS) Structure for NDRO-type FRAM Devices

We have fabricated Pt/SBT/insulator/Si structure for the transistor gate in MFIS-FET and investigated the electrical properties of MFIS structure with various insulator materials. SrBi₂Ta₂O₉ films as a ferroelectric layer were deposited by metal organic decomposition (MOD) technique, on various insulator structures including SiON, and Al₂O₃ as well as on Pt/Ti/SiO₂/Si structures. The effect of annealing temperature on the electrical properties of MFIS structures was investigated in order to analyze the applicability to conventional CMOS process. Although the remnant polarization of SBT films for MFM structure was increased with increasing annealing temperature, the memory window which has a relationship with remnant polarization of ferroelectrics was differently displayed with insulator structure in MFIS structure.     

Hydrothermal synthesis of porous octahedral Cu microcrystals and their application as hydrogen peroxide sensors

The novel porous octahedral Cu microcrystals were synthesized successfully by a simple one‐step hydrothermal reduction method based on TEA technique. The X‐ray diffraction (XRD) patterns reveal that Cu microcrystals have octahedral crystalline phase and high purity. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies represent that Cu microcrystals have a porous structure on their surface and polycrystalline structure. The asprepared porous Cu structures exhibited good ectrocatalytic activity in response to H₂O₂ reduction and can be used as H₂O₂ sensor. Furthermore, the possible formation mechanism of the POCu was proposed.     

Optical properties of the germanate melilites Sr2MgGe2O7, Sr2ZnGe2O7 and Ba2ZnGe2O7

Refractive indices and their dispersion in the wavelength range from 365 nm to 2325 nm and transmission ranges of the tetragonal melilite‐type germanates Sr₂MgGe₂O₇, Sr₂ZnGe₂O₇ and Ba₂ZnGe₂O₇ were determined. The uniaxial positive crystals Sr₂MgGe₂O₇ and Ba₂ZnGe₂O₇ both offer the possibility for phase matched second harmonic generation, a detailed analysis of phase matching conditions is given. The refractive indices of Sr₂ZnGe₂O₇ show an isoindex (isotropic) point at 467 nm. The investigation was performed on Czochralski grown large single crystals. The crystal structure of all three germanates were determined by means of X ‐ray diffraction. The results corroborate unmodulated melilite‐type structures at room temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and crystal structure of cyanocadmate clathrate with 2-methylimidazole (2-Meim): [Cd3(CN)6(2-Meim)2] ⋅ 2Me2SO

The cyanocadmate clathrate with 2-methylimidazole, [Cd₃(CN)₆(2-Meim)₂] 2Me₂SO, has been prepared and its crystal structure analyzed by X-ray diffraction method. This clathrate crystallizes in the orthorhombic system, space group Pbcn, with a = 13.237(3), b = 14.870(3), c = 14.698(3) Å, V = 2893.1(10) ų, Z = 4. The three-dimensional (3D) host framework is built of the cyanide bridges among two kinds of Cd ions, octahedral and tetrahedral in a ratio of 1:2. The octahedral Cd(1) center is linked to six tetrahedral Cd atoms; the tetrahedral Cd(2) center is linked to three octahedral Cd atoms and ligated by one 2-methylimidazole ligand. The novel host structure provides two types of channel, vacant distorted-diamond channel and rectangular channel which is occupied by dimethylsulfoxide guest molecule and 2-methylimidazole ligand coordinated to the tetrahedral Cd site.     

Solvothermal synthesis of mesoporous slabstone‐like TiO2 and its photodegradation preference in a methyl orange‐rhodamine B mixture solution

Mesoporous slabstone‐like anatase TiO₂ micro‐nanometer composite structure has been successfully synthesized by a facile solvothermal method at 180 °C using polyethylene glycol (PEG) as a structure‐directing agent, followed by calcination at 400 °C for 2 h. The crystal structure and morphology of the product were characterized by XRD, SEM, TEM and HRTEM. Its BET specific surface area was obtained from N₂ adsorption‐desorption isotherm measurement. Rhodamine B (RB) aqueous solution was used to evaluate the photocatalytic activity of the as‐prepared TiO₂ under simulated sunlight irradiation and compared with that of commercial TiO₂ (P25). A RB and methyl orange (MO) coexisting solution was chosen to investigate the photodegradation preference of the slabstone‐like TiO₂ on these two dyes. The results show that the photocatalytic activity of the as‐prepared TiO₂ is much higher than that of P25, and MO is the preferential degradation species in the MO‐RB mixture solution.     

Structural characterization of a zinc(II) complex of a tris(oxime)amine ligand

The ligand tris(1-propan-2-onyl oxime)amine (TRISOXH₃) binds to zinc(II) acetate as a tridentate N₃ donor, with a third oxime group remaining unbound and extending into the crystal lattice. The crystal structure shows a distorted trigonal bipyramidal geometry around the zinc center. An intramolecular hydrogen bonding interaction between a coordinated oxime donor and an oxygen of a bound acetate is observed. This structure is similar to that of a previously reported zinc(II) complex of a related bis(oxime)amine ligand. However, the structure of Zn(TRISOXH₃)(OAc)₂ is different in ligand coordination mode and metal coordination number from those of the previously reported complexes Ni(TRISOXH₃)Cl₂ or [Ni(TRISOXH₃)(NO₃)(H₂O)]NO₃.     

Molecular co-crystals of carboxylic acids, part 29. The effect of competitive interactions on adduct formation involving 2-aminopyrimidine: the crystal structure of the 1∶1 adduct of 2-aminopyrimidine with indole-2-carboxylic acid

The crystal structure of the 1∶1 adduct of 2-aminopyrimidine with indole-2-carboxylic acid has been determined by single crystal X-ray diffraction, revealing a novel interactive mode. The utility of 2-aminopyrimidine in formation of stable hydrogen-bonded networks with carboxylic acids is discussed and the modes of interaction are reviewed. Part 28.,Aust. J. Chem., 1997, (submitted).     

Crystal structure of 2‐(3‐amino‐2,4,4‐tricyano‐buta‐1,3‐dienyl)‐ thiophene

The title compound (C₁₁H₆N₄S) crystallizes in the orthorhombic space group Pbca with a = 23.561(4) Å, b = 7.064(1) Å, c = 13.018(3) Å, Z = 8; D_x = 1.387(1) g.cm^‐3 ; R = 0.073 for 1697 observed reflections [F2 ≥ 2σ(F²)]. The interesting feature is disorder in the crystal structure resulting from the existence of two isomeric molecules with interchangable carbon and sulfur positions, occuring at random but with equal probability in the structure.     

Heterodoped nanoflakes: synthesis and characterization of sulfur‐doped NbSe2 nanoflakes

Doping of NbSe₂ with heteroatoms is an effective way to tailor its properties. Here, solid phase synthesis process has been utilized for growing uniform and excellent crystalline nano‐NbSe₂ by sulfur dopant during the growing process. The sulfur‐doped mechanism of nano‐NbS_2xSe_2(1‐x)(x = 0.03∼0.2) has been investigated: the sulfur atoms not only replace the Se position but also intercalate in layer gap by one‐step reaction. In the structure of NbSe₂, the sulfur atoms replace the positions of Se atoms and then are located in the empty octahedral positions of van der waals gap between the NbSe₂ layers with the increase of sulfur content. The lubrication properties of the as‐prepared NbSe₂ and sulfur‐doped NbSe₂ powders as additives in HVI1500 base oil were discussed. The lubrication properties of base oil was improved by both NbSe₂ and sulfur‐doped NbSe₂. Furthermore, the lubrication properties of sulfur‐doped (0.1at%) NbSe₂ are better than those of pure NbSe₂ in HVI1500 base oil, which could be attributed to their thin laminated structure and the sulfur dopant.     

Large-size β-Ga2O3 single crystals and wafers

Large-size single crystals of β-Ga₂O₃ with 1 inc in diameter have been grown by the floating zone technique. The stable growth conditions have been determined by the examination of the crystal structure. Wafers have been cut and fine polished in the (1 0 0), (0 1 0) and (0 0 1) planes. These were highly transparent in the visible and near UV, as well as electrically conductive, indicating the potential use of β-Ga₂O₃ as a substrate for optoelectic devices operating in the visible/near UV and with vertical current flow.     

Growth characteristics of ultra long double-ended acicular ZnO synthesized by a hydrothermal process

Double-ended acicular ZnO structure can be synthesized via a hydrothermal process with tetramethylammonium hydroxide and zinc acetate as precursors and polyvinyl alcohol (PVA) as a structure-directing agent. The as-prepared ZnO products show the well crystalline wurtzite structure with growth direction along [0 0 0 1]. For the first time, PVA is found to be employed as a reservoir of Zn²⁺ ions in the present study, and can control the concentration of Zn²⁺ in reaction solution, and the acicular morphology can be formed at the two ends of the 1-D ZnO structure, due to the effect of secondary growth that occurs as the sufficient concentration of Zn²⁺ ions chelated by PVA releasing to the reaction solution. Furthermore, the size of the 1-D ZnO structure can be tuned by different amounts of PVA addition.     

Spectroscopic Investigation on the Formation of a Dinuclear Me2SO–Ru2-Mercaptopyridine Bridged Complex: [Ru2Cl3(μ-pyS)(μ-dmso)(dmso)4]?·?2H2O

Abstract  A dinuclear ruthenium(II) complex double-bridged by an N-aromatic ligand 2-mercaptopyridine (2-pyridinethiol or 2-pyridyl mercaptan) and a methyl sulfoxide (dmso) have been characterized by X-ray crystallography. The reported compound with formula [Ru₂Cl₃(μ-pyS)(μ-dmso)(dmso)₄] · 2H₂O, [C₁₅H₃₆Cl₃NO₇S₆Ru₂] (P2/c, a = 13.8175(2) ?, b = 10.5608(2) ?, c = 21.3544(3) ?, β = 106.090(1)°, V = 2,994.05(8) ?³, Z = 4) represents a seven-membered ring system with both rutheniums in an octahedral geometry. All the hydrogen bonds (C–H–Cl) and the van der Waals contacts give rise to three-dimensional network in the structure and add stability to the dinuclear compound. To our knowledge, this is the first time that the formation of a dinuclear ruthenium(II) complex double-bridged by an N-aromatic ligand 2-mercaptopyridine and dmso have been reported. The study also provided valuable insight into bioinorganic chemistry as continuing efforts are being made to develop metal-based cancer chemotherapeutics. A major feature of this paper is the resolution of a double bridged ruthenium structure which contributes to a better understanding of ruthenium reactivity. Index Abstract  A major feature of this paper is the resolution of a double bridged ruthenium structure which contributes to a better understanding of ruthenium reactivity.      

Synthesis of Layered-Structure LiFeO2

Abstract

LiFeO₂, with a layered rocksalt structure of α-NaFeO₂-type was prepared by ion exchange reaction from Na⁺ ion to Li⁺ ion using α-NaFeO₂. α-NaFeO₂-type LiFeO₂ was synthesized by using the mixture of LiI and KI in the temperature range 220 to 480 °C. The heat treatment temperature of 600 °C gave α-LiFeO₂-type LiFeO₂ as a main product. As a result of Rietveld analysis, the structure of LiFeO₂ which assigned to α-NaFeO₂-type by an XRD measurement, was the mixture of α-NaFeO₂-type and Li-intercalated spinel-type structures.     

Rapid Synthesis of Polycrystalline CuGa1‐xInxTe2 Compounds

A series of CuGa_1‐xIn_xTe₂ bulk quaternary compounds (x=0.17, 0.33, 0.50, 0.67, 0.83) has been synthesized from the corresponding stoichiometric melts by a rapid cooling procedure. The same procedure was used to obtain the ternary bulk compounds CuGaTe₂ and CuInTe₂ with the aim to compare, according the Vegard law, the match between molar fraction of the indium (x) and the lattice parameters for the aforementioned quaternary compounds. The nature of the crystalline phases, the local structure homogeneity and stoichiometry of these compounds have been investigated by x‐ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The analysis revealed the presence of the chalcopyritic structure for all the samples.     

SiO2纳米线/纳米颗粒复合结构的制备及光致发光性能研究

采用热蒸发法制备了非晶SiO2纳米线/纳米颗粒复合结构,确定了非晶SiO2纳米线、微米颗粒及SiO2纳米线/纳米颗粒复合结构生长的工艺条件,并利用XRD、SEM、Raman、PL光谱等技术手段分析表征样品.实验结果表明,在不同的沉积温度范围内,生长样品的形貌和结构不同;SiO2纳米线/纳米颗粒复合结构的发光区与Si衬底明显不同,主要集中在黄绿光范围.     

Submicron rectangular hollow tube crystals of rutile-type GeO2

Single crystals of rutile-type GeO₂ having a structure equivalent to that of TiO₂, a well-known photocatalyst, have been grown for the first time in supercritical oxygen at approximately 5 GPa and 3000 K. The obtained crystals exhibit a rectangular hollow tube structure with submicron size (cross section with sides of ∼500 nm, wall thickness of ∼20 nm, and longitudinal length of ∼5 μm). These single crystals were grown within 1 s and along the c-axis surrounded by the (1 1 0) faces. The crystal growth mechanism strongly depends on the growth mechanism of rutile-type oxides, and the extremely short growing time is an important factor in the formation of hollow tube crystals.     

γ-Bi2Sn2O7的水热合成及其可见光区光电响应研究

本文采用水热法制备了γ-Bi2Sn2O7并研究了其在可见光区的光电响应.Bi2Sn2O7的晶体结构和光电响应特性分别用X射线衍射和表面光电压谱进行表征.研究结果表明,合成的Bi2Sn2O7呈现γ相立方结构,通过吸收光谱估算光学带隙为2.67eV,比α-Bi2O3(2.85eV)的光学带隙小.Bi2Sn2O7的光电响应相对于α-Bi2O3在可见光区展现出一定的优势,同时对外加电压有很强的响应.