Synthesis and characterizations of a magnesium metal–organic framework with a distorted (10, 3)-a-net topology

A magnesium metal–organic framework with a distorted (10, 3)-a-net topology has been synthesized under solvothermal conditions, and characterized by X-ray structure determination, thermogravimetric analysis, X-ray powder diffraction, IR, and nonlinear optical studies.     

5-(2-羟乙氧基)间苯二甲酸二甲酯的合成改进

研究了5-(2-羟乙氧基)间苯二甲酸二甲酯的合成反应,优化了合成的条件。通过加大环氧乙烷的量及新的加料方式,改进了合成条件:以5-羟基间苯二甲酸为原料,经过酯化反应及环氧乙烷的开环反应以71%的总产率制备了5-(2-羟乙氧基)间苯二甲酸二甲酯。新合成方法不需加压条件,也避免了Williamson反应所需的价格昂贵的溴乙醇或氯乙醇等试剂。     

B3O4(OH) · 0.5(C4H10N2): First organic–inorganic hybrid borate with a neutral layered framework

A novel hybrid borate B₃O₄(OH) · 0.5(C₄H₁₀N₂) 1 was synthesized under milder hydrothermal conditions. The product was characterized by a combination of elemental analysis, FT-IR, thermogravimetric analysis and powder X-ray diffraction, as well as single-crystal X-ray diffraction studies. The structure consists of two types of inorganic borate helices cohered by piperazine rings, giving rise to a neutral hybrid sheet. The adjacent layers are stacked in a parallel fashion and further stabilized by hydrogen bonding interactions.     

Carbon monoxide adsorption and dissociation on Mn-decorated Rh(1 1 1) and Rh(5 5 3) surfaces: A first-principles study

Efficient CO activation on Rh particles promoted by Mn cocatalysts is important to the activity for the conversion of the syngas (CO and H₂) to hydrocarbon and oxygenates. To study the effect of the step edge and promotion of Mn cocatalysts on CO activation, we studied the CO dissociation on Mn-decorated Rh(1 1 1) and stepped Rh(5 5 3) surfaces using density functional theory calculations. We found that the presence of the step edge and Mn stabilizes the transition state and reaction products: compared to clean Rh(1 1 1), calculated barrier for CO dissociation on Mn-decorated Rh(5 5 3) is lowered by about 1.60 eV, and corresponding reaction energies with respect to CO in gas phase changes from endothermic (0.21 eV) to strong exothermic (−1.73 eV). The present work indicates that the addition of Mn cocatalysts and decrease of Rh particle sizes improves greatly the activity of CO dissociation.     

Synthesis and characterization of poly(ethylene terephthalate‐co‐isophthalate)s with low content of isophthalate units

The objective of this work was to study the effect of the introduction of low amounts of isophthalate units on the mechanical properties, crystallization rates, and thermal parameters of poly(ethylene terephthalate). For this reason a series of five random poly(ethylene terephthalate‐co‐isophthalate) copolymers, containing 0.5, 1, 1.5, 2, and 4 mol % isophthalic acid, were prepared by the melt polycondensation process. The intrinsic viscosity of copolymers ranged between 0.7 and 0.8 dL/g. The increase of isophthalate content resulted in a significant decrease of the crystallization rates, but in a small decline of tensile strength, Young's modulus, and elongation at break, whereas tensile strength at yield point remained almost unaffected. Also, a decrease in the melting point was recorded, whereas the glass‐transition temperature was only very slightly affected. The higher decrease for the aforementioned parameters was noted for the copolymer with 4 mol % isophthalate units content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1931–1941, 2002     

Isomer dependent assembly of lead(II) compounds derived from 5-(n-pyridyl)tetrazole-2-isopropionic acid (n = 2,3)

Isomer plays a significant role in the formation of coordination compounds. Reactions of isomeric 5-(n-pyridyl)tetrazole-2-isopropionic acid (denoted as Hn-pytzipa, n = 2, 3) with Pb(NO₃)₂ under solvothermal conditions afforded two compounds with the same formula [Pb(2-pytzipa)₂]_n (1) and [Pb(3-pytzipa)₂]_n (2), respectively. In compound 1, 2-pytzipa acts as a tetradentate ligand via the pyridine-N and the tetrazole-N in a chelating mode and the carboxylate group in a μ_1,3-COO chelating mode. In contrast, 3-pytzipa in compound 2 acts as a tridentate ligand by only the pyridine-N and the carboxylate group in a μ_1,3-COO chelating mode, whereas all the nitrogen atoms of the tetrazole ring are uncoordinated. Compound 1 shows a ladder-like chain while compound 2 displays a wave like chain. In addition, the photoluminescence properties of these ligands and compounds 1 and 2 in the solid state were investigated at room temperature. The thermal behavior of such compounds were also discussed.     

Solvothermal synthesis,crystal structure and photoluminescent property of a novel 3-D magnesium metal–organic framework Mg1.5(μ5-btec)(H2O)2] · [H2N(CH3)2] · H2O

A novel 3-D magnesium metal–organic framework [Mg_1.5(μ5-btec) (H₂O)₂] · [H₂N(CH₃) ₂] · H₂O (btec = 1,2,4,5-benzenetetracarboxylic acid) has been synthesized under solvothermal conditions, and characterized by single-crystal X-ray structure determination, thermogravimetric analysis, X-ray powder diffraction, IR, and photoluminescent studies.     

The phase stability and thermophysical properties of InFeO3(ZnO)m (m = 2, 3, 4, 5)

The phase stability and thermophysical properties of InFeO₃(ZnO)_m (m = 2, 3, 4, 5) compounds were investigated, which are a general family of homologous layered compounds with general formula InFeO₃(ZnO)_m (m = 1–19). InFeO₃(ZnO)_m (m = 2, 3, 4, 5) ceramics were synthesized using cold pressing followed by solid-state sintering. They revealed an excellent thermal stability after annealing at 1450 °C for 48 h. No phase transformation occurred during heating to 1400 °C. InFeO₃(ZnO)₃ exhibited a thermal conductivity of 1.38 W m⁻¹ K⁻¹ at 1000 °C, which is about 30% lower than that of 8 wt.% yttria stabilized zirconia (8YSZ) thermal barrier coatings. The thermal expansion coefficients (TECs) of InFeO₃(ZnO)m bulk ceramics were in a range of (10.97 ± 0.33) × 10⁻⁶ K⁻¹ to (11.46 ± 0.35) × 10⁻⁶ K⁻¹ at 900 °C, which are comparable to those of 8YSZ ceramics.     

Complex formation between copper(II) and poly-N5-(3-hydroxypropyl)-l-glutamine

Summary The complex formed between copper(II) and a polymeric ligand derived from poly-N⁵-(3-hydroxypropyl)-l-glutamine (PHPG) has been investigated by circular dichroism. It was found that the confonnational changes of PHPG occurred by forming complexes with Cu(II) according to the Cu/HPG molar ratios and different pH values. The helical structure was induced in PHPG by bound Cu(II) at Cu/peptide ratios< 1/16, while the structure changed from -helix to the random coil and -form at Cu/peptide ratios >1/16. It was also found that complex formation between Gu(II) and PHPG occurred above pH 9.5.     

Synthesis and crystal structures of n = 3 Ruddlesden–Popper phase CaSr3Mn3−xFexO10 (x = 1.5, 1.0)

The triple layer Ruddlesden–Popper phases (n = 3 R–P phase) CaSr₃Mn_3−xFe_xO₁₀ (x = 1.5, 1.0) were stabilized by solid state reaction in air atmosphere and their crystal structures were refined with neutron diffraction data obtained at room temperature and at 5 K by means of Rietveld method. Both phases adopt space group I4/mmm and revealed no magnetic reflection at low temperature. Magnetic susceptibility data of CaSr₃Mn_1.5Fe_1.5O₁₀ and CaSr₃Mn₂FeO₁₀ compound showed spin glass transition at 25 and 12 K, respectively.     

Synthesis and structures of dinuclear copper(II) complex and μ-phenolatotetrazinc(II) complex with 1,3-diphenyl-4-(salicylidene hydrazone)-phenylethylene-pyrazolone-5

Novel dinuclear copper(II) complex and phenoxy-bridged tetranuclear zinc(II) complex with 1,3-diphenyl-4-(salicylidene hydrazone)-phenylethylene-pyrazolone-5 (DPPeP-SAH) have been synthesized and characterized by X-ray crystallography. The X-ray diffraction analyses of the complexes show that two Cu(II) centers are bonded with two tetradentated ligands and the geometries around the central ions are slightly distorted square planar, while in zinc(II) complex central metal ions are held together by four μ-phenoxo bridges that lead to the formation of the tetra-μ-phenolatotetrazinc(II) centers.     

A 3D heteropolynuclear network with 4,6-connected (44 · 62)(48 · 66 · 8) topology: Synthesis,structure, thermal and magnetic properties

This paper describes a novel heteropolynuclear coordination polymer [Cd₄Co₂(m-BDC)₆(HIm)₄]_n (1) (m-H₂BDC = 1,3-benzenedicarboxylic acid, Him = imidazole), which has been hydrothermally prepared and characterized by single-crystal X-ray diffraction, IR, ICP, XRPD, TGA, DSC, and element analysis. The overall architecture is constructed from alternate Co(II) and Cd layers arranged in ABAB mode, and affords a three-dimensional (3D) 4,6-conneccted (4⁴ · 6²)(4⁸ · 6⁶ · 8) topological network. Furthermore, magnetic property of 1 has also been studied in the temperature range of 5–300 K.     

5－（3，5－二溴－2－吡啶基）－1－（2－羟基－5－磺苯基）－3－（2－羟基苯基）甲的合成及其与铜显色反应的研究

介绍了显色剂５－（３，５－二溴－２－吡啶基）－１－（２－羟基－５－磺苯基）－３－（２－羟基苯基）甲（ＢＰＨＰＳ）的合成。详细研究了试剂与铜的显色反应，其灵敏度较高，摩尔吸光系数ε为２．４６×１０４。采用掩蔽方法，能显著提高体系的选择性。用拟定的方法测定了铜矿中的铜，结果令人满意。     

3(5)-[(4-苄氧基)苯基]-5(3)-(2-呋喃基)-1H-吡唑的合成及结构确证

β-二酮和水合肼反应合成了标题化合物,采用元素分析、IR、1HNMR和ESI-MS对其结构进行了鉴定和分析.由于这种1H-吡唑化合物能形成N-H...N分子间的氢键,因而在ESI-MS图上出现很强的二聚体离子峰[2M]+.     

Microstructural characterization and crystallization behaviour of (1 − x)TeO2–xWO3 (x = 0.15, 0.25, 0.3 mol) glasses

DTA, XRD and SEM investigations were conducted on the (1 − x)TeO₂–xWO₃ glasses (where x = 0.15, 0.25 and 0.3). Whereas the 0.75TeO₂–0.25WO₃ and 0.7TeO₂–0.3WO₃ glasses show no exothermic peaks, an indication of no crystallization in their glassy matrices, two crystallization peaks were observed on the DTA plot of the 0.85TeO₂–0.15WO₃ glass. On the basis of the XRD measurements of the 0.85TeO₂–0.15WO₃ glass samples heated to 510 °C and 550 °C (above the peak crystallization temperatures), α-TeO₂ (paratellurite), γ-TeO₂ and WO₃ phases were detected in the sample heated to 510 °C and the α-TeO₂ and WO₃ phases were present in the sample heated to 550 °C. SEM micrographs taken from the 0.85TeO₂–0.15WO₃ glass heated to 510 °C showed that centrosymmetrical crystals were formed as a result of surface crystallization and were between 3 μm and 15 μm in width and 12 μm and 30 μm in length. On the other hand, SEM investigations of the 0.85TeO₂–0.15WO₃ glass heated to 550 °C revealed the evidence of bulk massive crystallization resulting in lamellar crystals between 1 μm and 3 μm in width and 5 μm and 30 μm in length. DTA analyses were carried out at different heating rates and the Avrami constants for the 0.85TeO₂–0.15WO₃ glass heated to 510 °C and 550 °C were calculated as 1.2 and 3.9, respectively. Using the modified Kissinger equation, activation energies for crystallization were determined as 265.5 kJ/mol and 258.6 kJ/mol for the 0.85TeO₂–0.15WO₃ glass heated to 510 °C and 550 °C, respectively.     

New [2 × 2] cyclic framework that induces distortions from square planar to tetrahedral around the copper(II) centers

A new tetracopper(II) complex [Cu₄(bsbd)₄] (bsbd = bis(N-salicylidene)benzene-1,4-diamine) has been prepared and structurally characterized. The complex constructs a [2 × 2] cyclic coordination framework, which inhibits formation of square planar copper(II) centers, and induces distortion to a tetrahedral structure. The effects of the distortions on the absorption spectra are characterized.     

含取代吡唑基的1,2,4-三唑并[3,4-b]-1,3,4-噻二唑类化合物的合成与波谱表征

通过3-烷基／芳基-4-氨基-5-巯基-1,2,4-三唑与1-苯基-3-甲基-5-氯吡唑甲醛进行分子内的Mannich反应,合成了12个标题化合物,并经元素分析、红外光谱、核磁共振氢谱确证结构,讨论了,其波谱性质。     

(5Z,9Z)-3-alkyl-5-methylindolizidines fromSolenopsis (Diplorhoptrum) species

The alkaloidal venom components of two species of thief ants,Solenopsis (Diplorhoptrum) species AA andS. (Diplorhoptrum)conjurata have been found to contain (5Z,9Z)-3-hexyl-5-methylindolizidine and a mixture of (5Z,9Z)-3-ethyl-5-methylindolizidine andcis-2-methyl-6-nonyl-piperidine,trans-2-methyl-6-nonylpiperidine,cis-2-methyl-6-undecylpiperidine, and hexadecanoic acid.Monomorium pharaonis was similarly investigated and found to contain the indolizidine and pyrrolidines previously described (Ritter et al., 1977b). Both indolizidines were synthesized along with their stereoisomers and separated by preparative gas chromatography. Spectral studies revealed the stereochemistry to be 5Z,9Z in both cases. The stereochemistry of 2-butyl-5-pentylpyrrolidine inM. phaeronis has also been established. Biosynthetic relationships are discussed.