Nonlinearity in regulating the metal to insulator transition of ReNiO3 towards low temperature range

Among the existing material family of the correlated oxides, the rare earth nickelates (ReNiO₃) exhibit broadly adjustable metal to insulator transition (MIT) properties that enables correlated electronic applications, such as thermistors, thermochromics, and logical devices. Nevertheless, how to accurately control the critical temperature (T_MIT) of ReNiO₃ via the co-occupation of the rare-earth elements is yet worthy to be further explored. Herein, we demonstrate the non-linearity in adjusting the T_MIT of ReNiO₃ towards lower temperatures via introducing Pr co-occupation within ReNiO₃ (e.g., Pr_xNd_1-xNiO₃ and Pr_xSm_1-xNiO₃) as synthesized by KCl molten-salt assisted high oxygen pressure reaction approach. Although the T_MIT is effectively reduced via Pr substitution, it does not strictly follow a linear relationship, in particular, when there is large difference in the ionic radius of the co-occupation rare-earth elements. Furthermore, the most significant deviation in T_MIT from the expected linear relationship appears at an equal co-occupation ratio of the two different rare-earth elements, while the abruption in the variation of resistivity across T_MIT is also reduced. The present work highlights the importance to use adjacent rare-earth elements with co-occupation ratio away from 1:1 for achieving more linear adjustment in designing the metal to insulator transition properties for ReNiO₃.     

Piezoelectric properties of [001]-textured high-power PMnN-PZT piezoceramics sintered at a low temperature

The 1.0 mol% CuO-added 0.14Pb(Mn1/3Nb2/3)O₃-0.86Pb(Zr_0.55Ti_0.45)O₃ (CPMnN-PZT) piezoceramics were synthesized at low temperatures (≤ 950 °C) by the columbite method to remove the pyrochlore phase. It exhibited a high Q_m of 3016 and a high T_C of 309 °C. However, it showed small d₃₃ and k_p values of 143 pC/N and 0.43, respectively. The CPMnN-PZT piezoceramic was textured along the [001] direction using BaTiO₃ (BT) templates to enhance its soft piezoelectric properties. The [001]-textured CPMnN-PZT + y vol% BT piezoceramics (1.0 ≤ y ≤ 5.0) were densified at a low temperature of 950 °C with a high Lotgering factor (≥ 92%). The textured sample (y = 1.0) showed a high Q_m of 1400 with increased d₃₃ and k_p values of 278 pC/N and 0.58, respectively, and its piezoelectricity showed excellent temperature stability up to 225 °C. Therefore, the textured CPMnN-PZT sample can be used for developing high-power piezoelectric devices.     

Characterization of acid properties of [Al]- and [Ga]-HZSM-5 zeolites by low temperature Fourier transform infrared spectroscopy of adsorbed carbon monoxide

[Al]- and [Ga]-HZSM-5 having closely similar acid site densities were prepared. Temperature-programmed desorption of ammonia (TPDA) proved the known acid strength sequence: [Al]>[Ga]. Frequency shifts of the OH stretching mode to lower frequencies were induced upon CO adsorption at 77 K due to OH CO H-bonding interactions. These frequency shifts are a measure of the H-bond donor strength of the OH groups and hence, of their acidic strength. The observed shifts of 313 and 282 cm^–1 for the [Al]- and [Ga]-silicate, respectively, clearly reflect their relative acid strength. [Ga]-HZSM-5 develops an acid strength similar to that found for HNaY at high exchange levels. Evidence is presented for an intrinsic heterogeneity of acid properties of the acidic hydroxyls probably caused by inhomogeneous distributions of the trivalent cations in the framework.On leave from Institute of Petroleum and Chemistry, M. Azizbekov, Baku, Azerbeidjan.     

[Fe(C7H5O3)(C9H6NO)2]三元配合物的合成及抑菌性能

本文以水杨酸、8-羟基喹啉为配体与铁(Ⅲ)合成了三元配合物,用元素分析、红外光谱、紫外可见光谱、荧光光谱等手段对其进行表征,确定其化学组成为[Fe(C7H5O3)(C9H6NO)2]。其中水杨酸脱质子以羧酸根与Fe3+成键,酚羟基不参与配位,而8-羟基喹啉脱质子以酚羟基氧和杂环上的氮原子双齿配位,形成五元螯环。配合物在整个可见光区都有较强吸收,粉末及其浓溶液均呈黑色,稀溶液显紫色。以300 nm为激发波长时,三元配合物在409 nm处有较强的发射荧光。采用分光光度法研究其对大肠杆菌生长的作用,配合物摩尔浓度低于2 mmol/L时,促进大肠杆菌的生长,高于2 mmol/L时抑制其生长,浓度越大抑制作用越强,即配合物对大肠杆菌的生长具有双向生物效应。     

[Fe(C7H5O3)(C9H6NO)2]三元配合物的合成及抑菌性能

以水杨酸、8-羟基喹啉为配体与铁(Ⅲ)合成了三元配合物,用元素分析、红外光谱、紫外可见光谱、荧光光谱对其进行表征,确定其化学组成为[Fe(C7H5O3)(C9H6NO)2]。其中,水杨酸脱质子以羧酸根与Fe3+成键,酚羟基不参与配位,而8-羟基喹啉脱质子以酚羟基氧和杂环上的氮原子双齿配位,形成五元螯环。配合物在整个可见光区都有较强吸收,粉末及其浓溶液均呈黑色,稀溶液呈紫色。以300 nm为激发波长时,三元配合物在409 nm处有较强的发射荧光。采用分光光度法研究其对大肠杆菌生长的作用,配合物浓度低于2 mmol/L时,促进大肠杆菌的生长,高于2 mmol/L时抑制其生长,浓度越大抑制作用越强,即配合物对大肠杆菌的生长具有双向生物效应。     

Pyrolo[1,2:4,5]-1,4-dioxopyrazino[1,2:1,6]pyrido[3,4-b]indoles: a group of urokinase inhibitors, their synthesis, and stereochemistry-dependent activity

Antifibrinolytic agents are required during complex surgeries to decrease bleeding; their pro-thrombotic potency and efficacy in causing hemostasis has attracted much attention. To discover new inhibitors of urokinase with high selectivity for antifibrinolytic effects over pro-thrombotic effects, the 12-position of (5aS,12S,14aS)- and (5aS,12R,14aS)-5,14-dioxo-1,2,3,5,5a,6,11, 12,14,14a-decahydro-5H,14H-pyrolo[1,2:4,5]pyrazino[1,2:1,6]pyrido[3,4-b]indoles were modified with L-Ala, L-Asp, L-Phe, L-Trp, L-Lys, L-Ser, Gly, and L-Leu to provide 16 (5aS,12S,14aS) and (5aS,12R,14aS) derivatives. In a murine bleeding model, the (5aS,12S,14aS) derivatives containing L-Ala, L-Asp, L-Phe, and L-Trp induced blood coagulation for the treated mice; they also stimulated thrombus formation in a rat thrombosis model, but the other derivatives inhibited thrombosis. The most potent compound, the L-Asp derivative, showed a good therapeutic window: the minimum effective dose for coagulation was <1 nmol kg(-1), whereas at 10 nmol kg(-1), no pro-thrombotic effect was observed. This type of coagulation action was correlated with a mechanism of urokinase inhibition, and these results could lead to the discovery of novel urokinase inhibitors.     

Co in diamond: Ferromagnetic ordering of a transition metal in diamond

Ferromagnetic ordering of dopants in semiconductors has attracted considerable interest, due to their relevance for “spintronic” applications. Diamond is a wide band gap semiconductor with extreme properties which make it suitable for high power, high frequency and high temperature applications. Up to now mainly other semiconductors have been considered in the search for dilute magnetic semiconductors (DMS). We report ab initio all electron, full-potential density functional theory modeling and show that the transition metal Co will order ferromagnetically when occupying a divacancy in diamond, forming a dilute magnetic semiconductor, with a magnetic moment of 0.4 μ_B per supercell, inducing two spin-polarized impurity bands in the diamond band gap. The impurity bands are shown to arise from the hybridization of the Co 3d level with diamond C 2p states.This demonstrates that diamond may be successfully considered in the search for ferromagnetically ordered semiconductors, in particular since diamond based DMS are expected to possess high Curie temperatures, in addition to the other extreme properties of diamond.     

Characterization of synthetic hydrocalumite-type [Ca2Al(OH)6]NO3·mH2O: Effect of the calcination temperature

A lamellar hydrocalumite-type [Ca₂Al(OH)₆]NO₃·mH₂O, (HC), was synthesized and characterized by X-ray diffraction analysis (XRD), surface area, pore size measurements, CO₂-Thermal Programmed Desorption, and later tested as catalysts in the double bond isomerization of 1-butene. The layered structure of HC collapses above 523 K yielding an amorphous material at 573 K which upon calcination at 873–973 K transforms into a mixture of CaO and mayenite Ca₁₂Al₁₄O₃₃. The calcination temperature has a marked effect in the formation of basic sites. Thus for example, HC calcined at 1073 K shows 90% of strong basic sites (CO₂ desorption at 1023 K) while they are absent in HC calcined at 573–673 K. HC calcined at 973 K shows high catalytic activity (74% conversion) in the isomerization of 1-butene without any appreciable deactivation after 4 h on stream.     

5-Methoxy, 7-methylbenz[a]anthracene: Crystal Structure of a Planar Weak Carcinogen

Abstract

The crystal and molecular structure of 5-methoxy,7-methylbenz[a]anthracene has been determined by X-ray diffraction at room temperature to an R-index of 0.062 over 936 reflections. The molecule, the first methoxy-substituted methylbenz[a]anthracene to be analysed, is highly planar, with the carbon and oxygen atoms of substituents lying within 0.04 Å of the mean plane of the polycyclic skeleton. Carbon–oxygen bond lengths in the methoxy group are unequal at 1.372(7) and 1.426(9) Å and the C_aromatic–O bond makes dissimilar angles of 113.5(7) and 124.3(7)° at C(5). The shortest C–C bonds are C(5)–C(6) = 1.351(9) at the substituted K-region, C(8)–C(9) = 1.352(9), C(10)–C(11) = 1.362(9) Å, and C(3)–C(4) = 1.361(10) Å. In the unsubstituted bay region, the long beach bond C(13)–C(18) = 1.454(9) Å is flanked by beach bond angles C(12)–C(18)–C(13) = 121.2(6) and C(18)–C(13)–C(1) = 123.1(6)°.     

Synthesis of ZSM-5 at low temperature and atmospheric pressure in a pilot-scale batch reactor

The synthesis of ZSM-5 was carried out at 100°C and atmospheric pressure in a 30 l batch reactor. The results show that a quality of ZSM-5 can easily be synthesized with a well-developed framework structure within 72 h of reaction. The crystallinity readily reached almost 100% and the yield was well over 70% for samples having various SiO₂/Al₂O₃ ratios. As the SiO₂/Al₂O₃ ratio decreased, the morphology changed from euhedral to spherulite along with an increase of aggregation. The average BET surface area of the samples was 371 m² g⁻¹ and nuclear magnetic resonance spectroscopic studies showed a quality of ZSM-5 with the least defect sites in the framework structure.     

Synthesis and structural characterization of a trispyrrole iron(II) complex K(dme)4[tpaMesFe] and application in nitrous oxide dependent coupling reactions

A new synthetic route to the trispyrrole iron(II) complex {K(dme)₄[tpa^MesFe]} was established starting from BOC-protected pyrrol via synthesis of the corresponding boronic acid, cross-coupling reaction, deprotection, triple Mannich reaction, a deprotonation and finally a salt metathesis. The complex was characterized and applied in iron-catalyzed coupling reactions. In more detail, with catalytic amounts of K(dme)₄[tpa^MesFe] the homo-coupling of aromatic Grignard reagents as well as the hetero-coupling of aromatic Grignard reagents were feasible. Noteworthy, to force the reaction nitrous oxide was added to realize yields up to 93% at mild reaction conditions.     

Synthesis,spectroscopic and structural aspects of triphenylantimony(V) complex with internally functionalized acetylferroceneoxime: Crystal and molecular structures of [C5H5FeC5H4C(CH3)NO]2SbPh3 and C5H5FeC5H4C(CH3)NOH

Triorganoantimony(V) complex (C₅H₅FeC₅H₄C(CH₃)NO)₂SbPh₃ (1) has been prepared by the reaction of Ph₃SbCl₂ with acetylferroceneoxime C₅H₅FeC₅H₄C(CH₃)NOH (2) in 1:2 molar ratio in anhydrous toluene. The complexes have been characterized by elemental analyses, IR and NMR (¹H and ¹³C) spectroscopic studies, and biologic activity was measured. And crystal structures of 1, 2 were reported. The coordination geometry around the antimony atom in 1 was slightly distorted trigonal bipyramidal with the carbon atoms of the SbPh₃ unit in equatorial positions and the two oxygen atoms of the oxime group occupying axial positions. The free oxime was clearly hydrogen bonded (H–N 2.10 Å/2.04 Å in 2) to essentially form a dimer.     

合成8-氯-10，11-二氢-4-氮杂-5H-二苯并[a，d]-5-环庚酮研究进展

介绍了氯雷他定的重要中间体8-氯-10,11-二氢-4-氮杂-5H-二苯并[a,d]-5-环庚酮的基本性质和用途,叙述了以2-溴-3-甲基吡啶、2-[（叔丁基氨基）]-3-甲基吡啶、3-甲基吡啶甲酸和3-吡啶甲酸乙酯为原料出发的合成方法。     

Hemoglobin Adducts of Benzo[a]Pyrene in Tobacco Smokers : Characterization of Benzo[a]Pyrene Adducts in Maternal and Fetal Blood Samples

The formation of hemoglobin - carcinogen adducts has been detected in carcinogen treated animals and in human populations. Although polynuclear aromatic hydrocarbons are ubiquitous in the human environment and DNA - aromatic hydrocarbon adducts have been detected in human tissue, the occurrence of hemoglobin - polynuclear aromatic hydrocarbon adducts in humans has not been thoroughly described. In this study we examined the effects of reaction condition on the extent of in vitro reaction of human hemoglobin and (+) [³H]benzo[a]pyrene-7,8-diol-9,10-epoxide (anti)(BPDE), a metabolite thought to be largely responsible for the carcinogenic effect of benzo[a]pyrene. The chromatographic properties of the resulting hemoglobin - BPDE adducts were examined by conventional DEAE-cellulose ion exchange liquid chromatography and by reversed phase high performance liquid chromatography. Several adducts were formed which were chromatographically resolved from hemoglobin and from the individual globins. We applied these techniques to the qualitative and quantitative assessment of benzo(a)pyrene hemoglobin adducts in smokers, correlating both maternal and fetal adducts with smoking status.     

Selective catalytic hydrogenations in a microfluidics-based high throughput flow reactor on ion-exchange supported transition metal complexes: A modular approach to the heterogenization of soluble complex catalysts

Water-soluble ruthenium(II) and rhodium(I) complexes containing monosulfonated triphenylphosphine (mtppms) ligands were immobilized on commercially available anion-exchangers. The resulting solid catalysts were suitable for use in a microfluidics-based flow reactor (H-Cube™) of high throughput capability. With the heterogenized [{RuCl₂(mtppms)₂}₂] disubstituted alkynes were hydrogenated to cis-alkenes with up to 85% selectivity, while the use of the immobilized [RhCl(mtppms)₃] yielded 1,2-diphenylethane as the major product. The ruthenium catalyst also reduced trans-cinnamaldehyde to 3-phenylpropanal selectively and catalyzed the isomerization of 1-octen-3-ol to octan-3-one. This simple and versatile method of the immobilization of water-soluble complexes yields active and durable molecularly dispersed yet solid catalysts.     

Synthesis,crystal structure,and optical property of a one-dimensional selenidostannate: [AEPPH2]2[Sn5Se12] (AEPP = N-aminoethylpiperazine)

A one-dimensional (1-D) selenidostannate, [AEPPH₂]₂[Sn₅Se₁₂] (AEPP = N-aminoethylpiperazine) (1), has been prepared under solvothermal condition and characterized. Single crystal X-ray analysis reveals that compound 1 crystallizes in the triclinic space group P-1, a = 10.6351(7) Å, b = 10.6850(7) Å, c = 10.7771(7) Å, α = 61.3440(10)°, β = 62.4420(10)°, γ = 67.4680(10). With distinct linkage modes between SnSe₄ tetrahedrons and SnSe₆ octahedrons, a secondary building unit (SBU) [Sn₅Se₁₄] is formed. Compound 1 contains infinite bead-like chains built up by the [Sn₅Se₁₄] SBUs, and the protonated [AEPPH₂]^2 + cations are located between the chain spaces. A pseudo 3-D network is formed through C–H···Se and N–H···Se hydrogen bonds between adjacent chains. Its optical property and theoretical band structure and density of state (DOS) calculations have also been studied.     

The novel polymeric potassium complex with a new coordination mode of orotic acid [K(μ5-H2Or)(μ-H2O)]n: Synthesis and structural characterization

Novel polynuclear seven-coordinated potassium complex, [K(μ₅-H₂Or)(μ-H₂O)]_n(H₃Or = orotic acid), with the new coordination mode of orotic acid has been prepared and characterized by elemental analysis, FT-IR spectra, X-ray diffraction. The orotate ligand exhibits new coordination mode of μ₅-κO, O: κO′, O′: O″ for H₂Or⁻.     

Catalytic NO reduction with ammonia at low temperatures on V2O5/AC catalysts: effect of metal oxides addition and SO2

The catalytic behavior of the V-M/AC (M=W, Mo, Zr, and Sn) catalysts were studied for the NO reduction with ammonia at low temperatures, especially in the presence of SO₂. The presence of the metal oxides does not increase the V₂O₅/AC activity but decreases it. Except V-Mo/AC, the other catalysts are promoted by SO₂ at 250°C, especially for V-Sn/AC. However, the promoting effect of SO₂ is gradually depressed by catalyst deactivation. Changes in catalyst preparation method can improve the catalyst stability in short-term but cannot completely prevent the catalyst from a long-term deactivation. Mechanisms of the promoting effect and the deactivation of V-Sn/AC catalyst by SO₂ were studied using Fourier transform infrared spectroscopy (FT-IR) spectra and measurement of catalyst surface area and pore volume. The results showed that both the SO₂ promotion and deactivation are associated with the formation of sulfate species on the catalyst surface. In the initial period of the selective catalytic reduction (SCR) reaction in the presence of SO₂, the formed sulfate species provide new acid sites to enhance ammonia adsorption and thus the catalytic activity. However, as the SCR reaction proceeds, excess amount of sulfate species and then ammonium-sulfate salts are formed which is stabilized by the presence of tin oxide, resulting in gradual plugging of the pore structures and the catalyst deactivation.     

Nitriles in heterocyclic synthesis: Synthesis of pyrazolo[1, 5-a] pyrimidine,pyrazolo[1, 5-c][1, 2, 4]triazine and pyrazolo[4, 3-e][1, 2, 4]triazine derivatives

5-Amino-3-phenylpyrazole ( 1 ) reacted with enaminonitriles 2a – c to afford the pyrazolopyrimidines 5a , b and the 5-substituted aminopyrazole 8 . 5a reacted with arenediazonium chlorides and benzaldehyde to give 6 and 7 respectively. Also, o-hydroxyacetophenone afforded the fused pyrazole derivative 9 on treatment with 1 . Enaminonitrile 3 coupled with 11 and arenediazonium chlorides to give 12 and 13 respectively. Cyclization of 13a , b afforded the pyrazolotriazines 15a , b .