Structure and conductivity in CeNb<Subscript>3</Subscript>O<Subscript>9-δ</Subscript>

Abstract  In the search of new materials for solid oxide fuel cells, a study of the structure and electrical conductivity of Mg-doped and nominally pure CeNb₃O_9-δ was undertaken. This material exhibits an orthorhombic crystal structure as determined by Rietveld refinement. Through a combined study of 4-point DC and AC impedance spectroscopy, it was determined that the material presents oxygen ion conductivity, electron conductivity and electron-hole conductivity according to the partial pressure of oxygen and temperature in agreement with a simple defect chemistry model. Finally, some experiments seem to indicate the presence of proton conduction. Graphical Abstract        

The diffusion of oxygen and ion transport in lanthanum cobaltite LaCoO<Subscript>3-δ</Subscript>

The chemical diffusion coefficient of oxygen vacancies and oxygen ion conductivity in lanthanum cobaltite LaCoO₃ were determined by the polarization method as functions of oxygen partial pressure \(p_{O_2 } \) (atm) and temperature T(K) over the ranges ?4 ≤ log \(p_{O_2 } \) ≤ 0 and 1173 K ≤ T ≤ 1323 K. The mobilities (cm²/(V s)) of oxygen vacancies calculated over the temperature range studied satisfy the inequalities 1.8 × 10^?5 ≤ \(v_{v_0 } \) ≤ 3.4 × 10^?5. The transfer numbers of oxygen vacancies were calculated. These numbers change depending on oxygen partial pressure over the range 5 × 10^?7 ≤ t ₀ ≤ 1 × 10^?5. The activation energy of self-diffusion of oxygen vacancies was found to be E _a= 104 ± 10 kJ/mol (1.1 ± 0.1 eV).     

β-胡萝卜素

本文从 β 胡萝卜素与维生素A的结构上分析 β 胡萝卜素与维生素A的关系 ;并联系生活实际阐明 β 胡萝卜素的性质、应用及防癌新功能。     

Wide-line <Superscript>1</Superscript>H NMR study of 4′-(pentyloxy)-4-biphenylcarbonitrile in different phase states

A sample of 4′-(pentyloxy)-4-biphenylcarbonitrile was studied in the temperature range 20–70°C by wide-line ¹H NMR. The line shapes, half-widths, and second moments were determined. At 20°C, the spectrum is a broad structureless line, which was split into three components at temperatures above 47°C. This pattern persisted up to 65°C, with the components becoming narrower. Above 68°C, the spectrum rapidly collapses to give a structureless narrow line with a width δH < 0.01 G. Analysis of the spectra and comparison with theoretical calculations made it possible to elucidate the transition of the sample from the crystalline to the nematic and isotropic phases, as well as to determine the temperature range of the stability of the liquid-crystalline phase and the role of rotational mobility of protons of different functional groups and sometimes of these groups as a whole in the mechanisms of phase transitions.     

新型手性<i>β</i>-烷氨基-<i>γ</i>-(<i>l</i>-孟氧基)丁内酯的合成

脂肪族伯胺作为亲核试剂与手性合成子5(R)-(l-孟氧基)-2(5H)-呋喃酮(4)发生不对称Michael加成反应, 得到一系列新的手性β-烷氨基-γ-(l-孟氧基)丁内酯类化合物6(产率34～81%, de≥98%). 通过IR, ¹H NMR, ¹³C NMR, MS, 元素分析及单晶X射线衍射分析, 确认了它们的化学结构、立体化学和绝对构型. 此结果为某些具有生物活性化合物及复杂分子的合成提供了新的途径.     

10,10’-二甲基-3,3’-二磺酸基-9,9’-双吖啶的电致化学发光行为

研究了新试剂10,10'-二甲基-3,3'-二磺酸基-9,9'-双吖啶(简称DMDSBA)的电致化学发光(ECL)行为. 考察了电化学参数、反应介质以及pH等条件对DMDSBA电致化学发光信号的影响. 结果表明, 在玻碳电极上施加适当电压时, DMDSBA在KNO₃溶液介质中产生很强的电化学发光信号, 于优化的实验条件下, 发光强度的自然对数与DMDSBA浓度的自然对数在1.0×10^-5-1.0×10^-8 mol·L^-1范围内呈良好的线性关系,检出限可达2.3×10^-9 mol·L^-1. 并用循环伏安法、电致化学发光光谱以及荧光光谱, 研究了DMDSBA的电致化学发光机理.     

(<Emphasis Type="Italic">S</Emphasis>)-(−)-α-Methylbenzylamine as chiral auxiliary in the synthesis of (+)-lortalamine

Abstract  (+)-Lortalamine was synthesised using (S)-(−)-α-methylbenzylamine as a chiral auxiliary. The stereochemistry of an intermediate compound was established on the basis of X-ray crystallography, allowing unambiguous assignment of the absolute configuration. Graphical abstract        

α -羟基-α -氨甲酰基酰胺类化合物的合成新方法

N, N-二甲氨酰基三甲基硅烷与一系列α -羰基酰胺在无水无氧、105 ℃的条件下反应, 较高产率地合成了α -羟基-α -氨甲酰基酰胺类化合物或α -三甲基硅氧基-α -氨甲酰基酰胺衍生物。 其结构用元素分析、¹H NMR、¹³C NMR和IR等技术手段进行了表征。 通过研究反应机理和影响反应的因素发现, 在α -羰基上连的烃基的空间位阻是该加成反应的重要影响因素, 而电子效应则影响反应的速率。 提出了可能的反应机理。     

Invar<Superscript>®</Superscript> oxidation in CO<Subscript>2</Subscript>

In this article, corrosion of Invar^® in a static carbon dioxide atmosphere \( 2\times 1 0^{4} \le P_{{{\text{CO}}_{ 2} }} \le 10^{5} \,{\text{Pa}} \) has been studied between 1163 and 1263 K. At the beginning, after a short initial deceleration for weight gains Δm/S <0.5 mg cm^?2, oxidation kinetics were linear up to weight gains of about 4.0 mg cm^?2, and only wüstite Fe_1?x O was formed with a constant rate r (mg cm^?2 s^?1) \( r = \frac{{{\text{d}}\left( {\frac{\Updelta m}{S}} \right)}}{{{\text{d}}t}} = 0.41 \times P_{{{\text{CO}}_{ 2} }} \exp \left( {\frac{ - 198000}{RT}} \right) \) where R is the gas constant and t the time (s). Reaction mechanism is similar to that of the pure iron in analogous conditions, with the same rate limiting step i.e. external reaction of CO₂ with wüstite and outward diffusion of ions Fe²⁺ (not limiting). For weight gains Δm/S higher than 4 mg cm^?2, the limiting step changes, with an increase of the reaction rate and an internal oxidation. The origin of this mechanism change lies in the microcracks appearing in the oxide during its growth. Then, wüstite is no longer bound to the substrate; outward diffusion of ions Fe²⁺ stops and a topotactic transformation converts wüstite into magnetite.     

新型螺[氧化吲哚-3,3′-吡唑]-5′-二氟甲基-4′-甲酸酯类化合物的合成

以原位生成的二氟甲基重氮甲烷（CF₂HCHN₂）与靛红衍生的3-烯基氧化吲哚为原料,通过[3+2]环加成反应和1,3-H迁移过程,合成了3种结构新型的螺[氧化吲哚 3,3′-吡唑]-5′-二氟甲基-4′-甲酸酯类化合物,收率41~68%, dr 91: 9~99 : 1,其结构经¹H NMR, ¹³C NMR, ¹⁹F NMR和HR-MS(ESI-TOF)表征。并通过单晶X-射线单晶衍射确定其相对构型。     

Heterometallic titanium–gold complexes inhibit renal cancer cells in vitro and in vivo

Following recent work on heterometallic titanocene–gold complexes as potential chemotherapeutics for renal cancer, we report here on the synthesis, characterization and stability studies of new titanocene complexes containing a methyl group and a carboxylate ligand (mba = S–C₆H₄–COO^–) bound to gold(i)-phosphane fragments through a thiolate group [(η-C₅H₅)₂TiMe(μ-mba)Au(PR₃)]. The compounds are more stable in physiological media than those previously reported and are highly cytotoxic against human cancer renal cell lines. We describe here preliminary mechanistic data involving studies on the interaction of selected compounds with plasmid (pBR322) DNA used as a model nucleic acid, and with selected protein kinases from a panel of 35 protein kinases having oncological interest. Preliminary mechanistic studies in Caki-1 renal cells indicate that the cytotoxic and anti-migration effects of the most active compound 5 [(η-C₅H₅)₂TiMe(μ-mba)Au(PPh₃)] involve inhibition of thioredoxin reductase and loss of expression of protein kinases that drive cell migration (AKT, p90-RSK, and MAPKAPK3). The co-localization of both titanium and gold metals (1 : 1 ratio) in Caki-1 renal cells was demonstrated for 5 indicating the robustness of the heterometallic compound in vitro. Two compounds were selected for further in vivo studies on mice based on their selectivity in vitro against renal cancer cell lines when compared to non-tumorigenic human kidney cell lines (HEK-293T and RPTC) and the favourable preliminary toxicity profile in C57BL/6 mice. Evaluation of Caki-1 xenografts in NOD.CB17-Prkdc SCID/J mice showed an impressive tumor reduction (67%) after treatment for 28 days (3 mg per kg per every other day) with heterometallic compound 5 as compared with the previously described [(η-C₅H₅)₂Ti{OC(O)-4-C₆H₄-P(Ph₂)AuCl}₂] 3 which was non-inhibitory. These findings indicate that structural modifications on the ligand scaffold affect the in vivo efficacy of this class of compounds.     

The sensor properties of SnO<Subscript>2</Subscript> · In<Subscript>2</Subscript>O<Subscript>3</Subscript> nanocomposite oxides in the detection of hydrogen in air

The sensor properties of In₂O₃ · SnO₂ polycrystalline films having different compositions were studied in the detection of 2% hydrogen in air over the temperature range 330–530°C. Films containing 19% In₂O₃ were most sensitive to hydrogen. The temperature dependence of the sensitivity of sensors passed a maximum, the position of which depended on the composition of the film. The temperature at which sensor sensitivity was maximum decreased as the content of indium oxide increased. This temperature was 485°C for the SnO₂ film and 425°C for the In₂O₃ film. The response and relaxation times of sensors also decreased as the amount of In₂O₃ in the composite metal oxide film increased. Possible mechanisms of the sensor sensitivity of the films are discussed.     

Reactivity of the oxides in the ternary V<Subscript>2</Subscript>O<Subscript>5</Subscript>-CuO-α-Sb<Subscript>2</Subscript>O<Subscript>4</Subscript> system in air

In this work it has been established which compounds finally are formed in air in the two-component CuO-V₂O₅ and CuO-α-Sb₂O₄ systems. Unknown thermal properties of CuV₂O₆, Cu₂V₂O₇ and Cu₁₁V₆O₂₆ have been established. Reactivity of the oxides and phase relations in the ternary V₂O₅-CuO-α-Sb₂O₄ system in air have been studied by using XRD and DTA methods. The results have showed the reaction of V₂O₅, CuO with α-Sb₂O₄ does not produce any compound where all the three oxides would be involved. It has been established that the α-Sb₂O₄ reacts and forms binary phases independently with CuO or V₂O₅. On the base of these results the investigated system was divided into subsidiary subsystem in which CuSb₂O₆ remains at equilibrium in the solid state with other phases formed in corresponding binary systems.     

Induction of radiative forbidden transitions in an oxygen molecule in O<Subscript>2</Subscript>–H<Subscript>2</Subscript>O collision complexes

By the DFT/B3LYP method the equilibrium structures of oxygen complexes with water are calculated in various geometric conformations with symmetries C _2v and C _s . By the MRCI/CASSCF method potential energy surface cross-sections of the ^1.3[O₂–H₂O] complexation reaction are constructed. With taking into account the spin-orbit coupling, the forbidden transition moments a ¹Δ _g –X ³Σ _g ^?, b ¹Σ _g ⁺–a ¹Δ _g , c ¹Σ _u ^?–a ¹Δ _g , A ³Σ _u ⁺–X ³Σ _g ^? of the complexes are calculated and changes in their intensities at different geometric configurations of the complex are revealed.     

Thermochemistry of glycyl-<Emphasis Type="Italic">DL</Emphasis>-α-alanine dissolution in water-alcohol solutions at 298.15 K

Integral enthalpies of glycyl-DL-α-alanine dissolution in aqueous solutions of ethanol, 1-propanol, and 2-propanol at concentrations of alcohols up to 0.4 mol fraction were measured by the calorimetry method. Standard values of the enthalpies of the peptide dissolution Δ_sol H ⁰ and transfer Δ_tr H ⁰ from water in mixed solvents were calculated. Dependences of the thermochemical characteristics of glycyl-DL-α-alanine dissolution on the concentration of cosolvents are of an extreme character. Within the limits of McMillan-Mayer’s theory enthalpy coefficients of pairwise interactions (h _xy ) of the studied compound with molecules of alcohols were calculated. They have positive values increasing in the series ethanol, 1-propanol, 2-propanol. The effect of the structure of dipeptides and composition of water-alcohol solvents on the dissolution enthalpy characteristics was considered on the basis of the obtained experimental and calculated data.     

5,5′-二甲基-2,2′-二茚满-1,1′,3,3′-四酮的合成及结构表征

本文以4-甲基邻苯二甲酸酐为原料, 成功地合成了5,5′-二甲基-2,2′-二茚满-1,1′,3,3′-四酮(2). 通过元素分析、核磁共振、红外光谱及质谱等测试手段, 确定了化合物2的结构与存在形式, 通过ESR测试发现化合物2具有顺磁性.     

Photochemistry of the IrCl<Subscript>6</Subscript><Superscript>2−</Superscript> complex in aqueous solutions in the presence of the bromide anions

Laser flash photolysis (308 nm) was applied to study photochemistry of the IrCl₆ ²⁻ complex in aqueous solutions in the presence of the Br⁻ anions. The formation of the Br₂ ^·− radical anions in the reaction between the Br⁻ ion and secondary radical pair formed after the photon absorption by the initial complex was observed. The Br₂ ^·− radical anions decay both in recombination and in the reaction with the initial IrCl₆ ²⁻ complex.