Absence of superconductivity in LiCu2P2

We successfully synthesized the copper-based pnictide LiCu(2)P(2), which was reported as a superconductor with T(c) = 3.7 K before. The temperature dependence of resistivity and DC magnetization was measured on both polycrystalline and single-crystalline LiCu(2)P(2). However, our repeatable synthesizing and measurements showed no superconducting transition either in resistivity or DC magnetization above 2 K. A metallic behavior can be seen in resistivity, and a Curie-Weiss behavior was observed in DC magnetization from 2 to 300 K. We have also carried out the Hall effect and MR measurements on the sample, from which we conclude that the LiCu(2)P(2) has a single-band character. We also synthesized the polycrystalline Li(1-x)Cu(2)P(2), LiCu(2-x)P(2), and Li(1+x)Cu(2-x)P(2) with different stoichiometries, and observed no superconductivity in all the samples.     

Radiolysis of 2-propanol in presence of 2-hexanoylfuran

2-hexanoyl-5-(2-hydroxy 2-propyl)furan (HHPF), has been investigated as the principal product of radiolysis of 2-hexanoyl-furan (HF) in 2-propanol. The effect of absorbed dose on the product yields has been examined. Possible mechanisms for the formation of radiolytic products are discussed.     

Insertion of acetylenes in the PdPd bond of Pd2 (Ph2 PCH2 PPh2)2 Cl2

Dimethylacetylene dicarboxylate and hexafluoro-2-butyne add to Pd₂(dpm)₂Cl₂ (dpm = Ph₂PCH₂PPh₂) to give crystalline adducts Pd₂(dp)₂(μ-acetylene)Cl₂. An X-ray crystal structure of Pd₂(dpm)₂(μ-C₄F₆)Cl₂ reveals that the acetylene has inserted into the metalmetal bond and has been transformed into a cis-dimetallated olefin. The central CC bond length of the bridging olefin is 1.338(16) Å. The coordination about each of the two similar palladium ions is planar and involves two trans-phosphines (one from each of the bridging dpm ligands), a terminal chloride, and one carbon of the bridging olefin. Both Pd₂(dpm)₂Cl₂ and Pd₂(dpm)₂(μ-C₂{CO₂H₃}₂)Cl₂ catalyze the cyclotrimerization of dimethyl-acetylene dicarboxylate.     

Synthesis of Gels in the System Na2O-ZrO2-SiO2

Gels have been synthesized in the SiO₂-Na₂O-ZrO₂ system and calcined at various temperatures up to 700°C. They have been studied by infrared absorption spectroscopy. The position of the asymmetric stretching frequency of the SiO₄ unit is used as a tracer of the homogeneity. It is shown that sodium increases the solubility of zirconium in the silica matrix as already observed in fused glasses.     

在乙二醇溶液中原位法制备纳米SnO2

乙二醇;锡配合物;溶胶 凝胶;纳米SnO2     

纳米ZrO2在O2/H2气中的表面效应

用ESR方法研究了一种纳米ZrO₂在普通H₂气中升温条件下的表面效应.ZrO₂上Zr³⁺的中心量约为1×10^-7mol/g.这些Zr³⁺中心是ZrO₂表面一些O^2-配位不饱和的Zr原子点位.在普通H₂气中,ZrO₂上的Zr³⁺中心数在温度低于400℃时变化很小.但在这一温度范围内从室温升温时,由ZrO₂表面羟基的H₂还原引起的F中心量随温度的升高而增加.温度高于400℃时,ZrO₂表面的Zr³⁺及F中心可与普通H₂气中存在的少量O₂气作用产生O₂^-,并伴随ZrO₂表面羟基的脱除而形成新的Zr³⁺.     

Radiolysis of 2-acetylfuran in 2-propanol in absence of atmospheric oxygen

Gamma radiolysis of 2-acetylfuran (AF) in 2-propanol, in absence of atmospheric oxygen, has been investigated. The radiation yields of hydrogen, methane at different doses as well as radiolytic products in solution were determined. The radiolytic products were determined by gas chromatography coupled with mass spectrometry. The mechanisms for formation of detected radiolytic products and the effect of (AF) concentration on hydrogen and methane yields are discussed.     

Interaction of components in the HgBr2-CdBr2-PbBr2 ternary system

The interaction in the HgBr₂-CdBr₂-PbBr₂ ternary system was studied by differential thermal analysis; the isoconcentration section of the system at 50 mol % CdBr₂ was investigated. Based on the results of the study, a projection of the liquidus surface of the HgBr₂-CdBr₂-PbBr₂ ternary system to the composition triangle was constructed; the boundaries of the primary crystallization fields were determined for three phases: HgBr₂ (degenerate field), solid solution α based on CdBr₂, and solid solution β based on PbBr₂; and isotherms were drawn. A ternary eutectic has the composition 93 mol % HgBr₂-1 mol % CdBr₂-6 mol % PbBr₂ and melts at 235°C.     

Hydrazinocyanation of 2, 2'-methylenedicyclohexanone in aqueous alcohol

The reaction of 2,2'-methylenedicyclohexanone with HCN and hydrazine in aqueous alcohol was studied at various pH values. Conclusions were drawn regarding the spatial configurations of the reaction products.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1387–1390, October, 1972.     

Formation of TiO2 nanoparticles in water-in-CO2 microemulsions

Titanium dioxide nanoparticles can be produced by the controlled hydrolysis of titanium tetraisopropoxide in water-in-CO2 (w/c) microemulsions stabilized with the surfactants ammonium carboxylate perfluoropolyether (PFPE-NH4) and poly(dimethyl amino ethyl methacrylate-block-1H,1H,2H,2H-perfluorooctyl methacrylate) (PDMAEMA-b-PFOMA); the greater control of hydrolysis and particle growth with PDMAEMA-b-PFOMA is consistent with the differences in the stabilities and interactions for these two microemulsions.     

Infrared studies of tautomerism in 2-hydroxypyridine 2-thiopyridine and 2-aminopyridine.

The infrared spectra of 2-hydroxypyridine (2-OHP), 2-thiopyridine (2-SHP), and 2-aminopyridine (2-NH2P) have been recorded in the solid, liquid and vapor phases in the region 4000-200 cm(-1). To support the work, deuterated forms of these compounds in the functional groups XH and NH with (X=O, S, NH) were recorded for the solid and liquid phases. The results show existence of each compound as an equilibrium mixture of two tautomers in monomeric and cyclic dimeric forms in the solid, liquid and vapor phases. The monomers are predominant in the vapor phase. Enthalpy differences between the monomeric tautomers and activation energies for their inter-conversion were determined in each phase.     

Formation and Crystallization Behavior of Gels in the Na2O-SiO2-TiO2-ZrO2 System

SiO₂-TiO₂-ZrO₂ and 5Na₂O·95(SiO₂ + TiO₂ + ZrO₂) gels were synthesized and role of Na₂O in gel formation and crystallization behavior of gels were studied. From Si(OC₂H₅)₄, Ti(iso-OC₃H₇)₄, Zr(n-OC₃H₇)₄ and NaOCH₃ solutions in EtOH without H₂O, transparent and opaque gels were obtained. Opaque bulk gels, rich in TiO₂ or ZrO₂ composition in Na₂O containing SiO₂-TiO₂-ZrO₂ system, contain agglomerated spherical particles of diameter small <10 m, in contrast with opaque gels having large particles <30 m in alkali-free SiO₂-TiO₂-ZrO₂ system. Crystallization temperature (Tc) was measured by DTA on dried gels. Compared with the alkali-free SiO₂-TiO₂-ZrO₂ gels, 5 mol% Na₂O containing gels gave lower Tc in SiO₂ rich compositions and higher in TiO₂ rich or ZrO₂ rich compositions.     

Alkenes in [2+2+2] Cycloadditions

Participation of alkenes and allenes in [2+2+2] cycloaddition reactions has attracted much attention recently. This version of the well‐established alkyne cyclotrimerization renders interesting products, such as cyclohexadienes and other polycycles, through cascade processes. Many mechanistic variations are observed when using certain metal complexes as catalysts. The frequent generation of stereogenic centers has prompted the development of efficient asymmetric versions. This Minireview summarizes the efforts reported to date on the use of double bonds as partners in [2+2+2] cyclotrimerizations.     

Collision-free lifetimes of selectivity excited levels in the 2B2-2A1 system of NO2

Time-resolved sub-Doppler laser spectroscopy under collision-free conditions in a supersonic NO₂ beam has proved that selectively excited rovibronic levels show only pure exponential decays with lifetimes from 40 to 100 μs depending on the strength of their coupling to non-radiative levels. These measurements support earlier results which can be explained by vibronic and spin-orbit coupling between levels in the ²B₂ and X²A₁ states.     

ZnAc2·2H2O在空气中的热分解动力学研究

用TG/DTA,DSC和XRD技术研究了固态物质ZnAc2.2H2O在空气中的热分解过程.结果表明,ZnAc2.2H2O在空气中发生两步分解,其失重率与理论计算失重率相符.XRD结果表明,ZnAc2.2H2O分解的最终产物为ZnO.用Friedman法和Flynn-Wall-Ozawa(FWO)法求得分解过程的活化能E,并通过多元线性回归方法给出了可能的机理函数.ZnAc2.2H2O在空气中两步分解的活化能分别为119.82和66.82kJ/mol.     

Enthalpy of solution of CO2 in aqueous solutions of 2-amino-2-methyl-1-propanol

The enthalpies of solution of CO₂ in aqueous solution of 2-amino-2-methyl-1-propanol (AMP) 15 wt% and 30 wt% were measured at 322.5 K and pressures range from (0.2 to 5) MPa using a flow calorimetric technique. The gas solubilities were simultaneously determined from the calorimetric data. The solubilities were compared to available literature values obtained by direct measurements. The experimental enthalpies of solution were compared to the values derived from the literature vapor liquid equilibrium data. This work provides calorimetric data that will be used later for the development of a thermodynamic model to predict both solubilities and enthalpies of solution of acid gases in aqueous amine solutions.     

Host-guest interactions in a series of self-assembled As2L2Cl2 macrocycles

The reaction of AsCl3 with H2L (where L = a rigid dithiolate) results in the self-assembly of As2L2Cl2 supramolecular macrocycles. For ligands 4,4'-bis(mercaptomethyl)biphenyl (H2), 4,4'-bis(mercaptomethyl)-trans-stilbene (H2), and 1,4-dimethoxy-2,5-bis(mercaptomethyl)benzene (H2), the macrocyclic cavities of the resulting assemblies are large enough to host aromatic solvent molecules, as revealed by single crystal X-ray structures of the inclusion complexes. As2L2Cl(2) macrocycles form in solution as a mixture of diastereomers, but the diastereomers can be selectively crystallized and separated. Crystallization of syn- or anti-As(2)3(2)Cl2 can be controlled using host-guest interactions by the prudent choice of crystallization solvents. anti-As(2)3(2)Cl2 crystallizes exclusively from chloroform and benzene, while a [(syn-As(2)(2)Cl(2))(2).p-xylene] dimer crystallizes from p-xylene and a mixture of [(syn-As(2)3(2)Cl(2))(anti-As(2)3(2)Cl2) x toluene] and [(syn-As(2)3(2)Cl2)2 x toluene] dimers crystallize from toluene.