Thermal analysis of transition metal and rare earth oxide system-gas interactions by a solid electrolyte-based coulometric technique

The oxidation-reduction behaviour of transition metal and rare earth oxide systems in oxygen potential controlled atmospheres was investigated by means of a solid electrolyte-based coulometric technique (SEC) in carrier gas mode to obtain information concerning the extent of oxygen stoichiometry, thep-T-x diagram of any mixed oxide phase, the kinetics of the oxygen exchange and the phase transitions.The direct coupling of SEC and electrical conductivity measurements provides further information about the relationship between oxygen deficiency and conductivity, especially as concerns the oxygen mobility and the transition from ionic to mixed ionic/electronic conductivity in any system.In the fluorite-type phases PrO_2–x, Ce_0.8Pr_0.2O_y–x and Ce_0.8Sr_0.08Pr_0.12O_y–x, the higher oxidation state of Pr is stabilized and the electrical conductivity increases in this sequence. The perovskite-type phase Sr_1–yCe_yFeO_3–x, shows transitions and a second phase reflected in the temperature-programmed spectrum of this substance. The electrical conductivity of Sr_0.9Ce_0.1FeO_3–x changes fromn-type top-type with increasing oxygen pressure.     

Nano‐synthesis and spectral,thermal, modeling,quantitative structure–activity relationship and docking studies of novel bioactive homo‐binuclear metal complexes derived from thiazole drug for therapeutic applications

Seven novel homo‐binuclear Cr(III), Fe(III), Cu(II), ZrO(II), Sn(II), Pb(II) and Ce(III) nanosized complexes of a thiazole drug (H₂L) were synthesized for chemotherapeutic applications. H₂L was prepared via a condensation reaction between 2‐(4‐aminobenzenesulfonamido)thiazole and 2‐hydroxybenzaldehyde. The structures of H₂L and its metal complexes were investigated by various means. These included microanalysis, ¹H NMR, ¹³C NMR, Fourier transform infrared, UV–visible, electron spin resonance and mass spectroscopies, transmission electron microscopy (TEM), powder X‐ray diffraction (XRD), thermogravimetric analysis (TGA) and molar conductivity. The measurements revealed that H₂L coordinates with the metal ions through two chelating centers, indicating its behavior as a dibasic tetradentate ligand. The first center involves the nitrogen of azomethine (CH═N) and the α‐hydroxyl oxygen while the other center is the thiazole nitrogen and the sulfonamide oxygen. From spectroscopic and analytical data, the Cr(III), Fe(III) and Ce(III) complexes have octahedral geometries, whereas the Cu(II), ZrO(II), Sn(II) and Pb(II) complexes have tetrahedral geometries. TEM and XRD measurements unambiguously showed the nanometric particle sizes of the complexes. The activation thermo‐kinetic parameters, E*, ?H*, ?S* and ?G*, of the various decomposition steps of the complexes were determined mathematically from the TGA curves. Gaussian09 and quantitative structure–activity relationship modeling studies were utilized to verify the biological and structural feature relationships. Docking studies were performed to throw more light on the biological priority of the proposed drugs, using microorganism protein receptors. The antitumor and antimicrobial efficiencies of the H₂L drug and its complexes were determined to estimate their potential therapeutic utility. In general, the complexes showed greater antitumor and antimicrobial efficiencies than the H₂L drug. The Fe(III) complex exhibited efficient antimicrobial activities against Candida albicans and Staphylococcus aureus and its efficiency is equivalent to that of standard drugs. The Cu(II) complex showed the greatest cytotoxic activity towards HEPG2.     

Mechanism of thermal decomposition of cobalt acetate tetrahydrate

The thermal decomposition of cobalt acetate tetrahydrate (Co(CH₃COO)₂ · 4H₂O) has been studied via thermogravimetric (TG) analysis, in situ X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results of TG and XRD showed that the parent salt melted and then the dissolved crystalline water was vaporized in two steps. The dehydration process was followed by a major step concerning the decomposition of the acetate group, leading to basic acetate as an intermediate, which then produced CoO and Co in N₂ and H₂ atmosphere, respectively. Three decomposition intermediates Co(CH₃COO)₂ · 0.5H₂O, Co(CH₃COO)₂, and Co(OH)(CH₃COO) were presumed. In situ XRD experiments revealed that the intermediate basic acetate was poorly crystallized or even amorphous. Evolved gases analysis indicated that the volatile products of acetate decomposition were water vapor, acetic acid, ethylenone, acetone, and CO₂. A detailed thermal decomposition mechanism of Co(CH₃COO)₂ · 4H₂O was discussed.     

基于8-羟基喹啉与d10金属原位合成的双核配合物的合成、晶体结构及其光致发光性质

利用8-羟基喹啉原位反应,通过溶剂热方法制备出3种新颖的d~(10)配合物[M_2(HL)_3]NO_3·H_2O (M=Cd (1),Zn (2,3)),H_2L为1,1-(7,7′-二-(8-羟基喹啉))。单晶结构表明,3种配合物有着相同的带正电荷的结构单元[M_2(HL)_3]~+,但由于客体分子所处空间位置的不同表现为不同的空间结构,配合物1和3结晶于六方晶系(P6_3/m),配合物2结晶于三方晶系(R3)。中心金属离子以六配位的模式与来自HL-配体上的3个氧原子和3个氮原子形成一个轻微扭曲的八面体几何构型。存在于HL-配体与客体分子(NO_3~-,H_2O)间大量的弱作用力在结构空间堆积上起到了重要的作用。3种配合物均具有良好的热稳定性和绿色荧光发射性质。同时,通过从配合物1中提取出原位生成的配体H_2L,首次报道了其蓝色荧光发射性质。     

In situ X-ray diffraction study of reduction processes of Fe3O4- and Fe1−xO-based ammonia-synthesis catalysts

The temperature-programmed reduction process of two types of industrial ammonia-synthesis catalysts, A110 and ZA-5, which are, respectively, based on Fe₃O₄ and Fe_1−xO precursors, were studied by in situ X-ray power diffraction (XRD). It has been found that the ZA-5 has lower reduction temperature and faster reduction rate, and its active phase α-Fe possesses a higher value of lattice microstrain than A110. The simulation based on Rietveld refinement has also shown that the shape of α-Fe grain of ZA-5 has a mixed shape of cube and sphere with more exposing (111) and (211) planes, while that of A110 looks like a concave cube with more exposing (110) planes. Based on the results obtained, a growth model of α-Fe during the reduction of Fe₃O₄- and Fe_1−xO-based ammonia-synthesis catalysts is proposed, and the origins for the activity difference has been also discussed.     

不同硅铝比Cu-ZSM-5纳米片上N2O催化分解

以双季铵盐表面活性剂为模板剂,水热条件下合成了硅铝比(nSi/nAl)为18、26和95的ZSM-5沸石纳米片,采用离子交换方法制备了铜改性的ZSM-5纳米片样品,并测试了其催化分解N_2O性能。结合X射线衍射(XRD)、N_2吸附/脱附、X射线荧光光谱(XRF)、扫描电镜(SEM)、透射电镜(TEM)、氢气程序升温还原(H_2-TPR)、氧气程序升温脱附(O_2-TPD)和原位红外漫反射光谱(CODRIFT)等表征结果 ,探讨了沸石硅铝比对于催化剂N_2O分解性能的影响及其原因。结果表明,ZSM-5纳米片硅铝比越低,CuZSM-5纳米片催化剂的活性越高。催化活性的提高归因于低硅铝比催化剂上Cu~+活性物种可还原性的增强和吸附氧脱附能力的提高。     

铁铈氧化物程序升温还原过程的研究

运用原位穆斯堡尔谱、XRD测定等方法剖析了铁铈氧化物的程序升温还原过程。结果表明，金属离子间的相互作用使得氧化铁的还原温度升高，还原反应活化能提高，抗还原能力增强。     

Experimental Evidence for a Calix[4]arene-Proton Complex

Summary. From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium H⁺(aq) + 1 ·Na⁺(nb) ⇆ 1 ·H⁺(nb) + Na⁺(aq) taking place in the two-phase water-nitrobenzene system (1 = p-tert-butylcalix[4]arene-tetrakis(N, N-diethylacetamide); aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex(H⁺, 1 ·Na⁺) = −1.4 ± 0.1. Further, the stability constant of the p-tert-butylcalix[4]arene-tetrakis(N,N-diethylacetamide)-H⁺ complex in water saturated nitrobenzene was calculated for a temperature of 25°C as log β_nb(1 · H⁺) = 8.1 ± 0.1.     

Thermo-Raman spectroscopy in situ monitoring study of solid-state synthesis of NiO-Al2O3 nanoparticles and its characterization

Hyphenation of thermogravimetric analyzer (TGA) and thermo-Raman spectrophotometer for in situ monitoring of solid-state reaction in oxygen atmosphere forming NiO-Al₂O₃ catalyst nanoparticles is investigated. In situ thermo-Raman spectra in the range from 200 to 1400 cm⁻¹ were recorded at every degree interval from 25 to 800 °C. Thermo-Raman spectroscopic studies reveal that, although the onset of formation is around 600 °C, the bulk NiAl₂O₄ forms at temperatures above 800 °C. The X-ray diffraction (XRD) spectra and the scanning electron microscopy (SEM) images of the reaction mixtures were recorded at regular temperature intervals of 100 °C, in the temperature range from 400 to 1000 °C, which could provide information on structural and morphological evolution of NiO-Al₂O₃. Slow controlled heating of the sample enabled better control over morphology and particle size distribution (∼20-30 nm diameter). The observed results were supported by complementary characterizations using TGA, XRD, SEM, transmission electron microscopy, and energy dispersive X-ray analysis.     

Spectrophotometric determination of oxygen content in calcium substituted RBCO (R=Eu,Gd, Er) superconductors

The oxygen stoichiometry in R_1−x Ca _x Ba₂Cu₃O _y (R=Eu, Er, Gd; x=0, 0.2, 0.25, 0.3) superconducting bulk samples was determined spectrophotometrically. The dependence of the critical temperature on the y-oxygen coefficient and the x-coefficient of the included calcium was studied.     

A TEM, XRD, and crystal chemical investigation of oxygen/vacancy ordering in (Ba1−xLax)2In2O5+x, 0x0.6

A careful TEM and XRD study of the (Ba_1−xLa_x)₂In₂O_5+x, 0x0.6, ‘defect-perovskite’-type solid solution has been carried out. A well-defined structural phase transition is shown to occur between x=0.1 and 0.2 from the orthorhombic brownmillerite structure type on the low x side to a multiple twinned, tetragonal 1×1×2 perovskite-related superstructure phase on the high x side at x=0.2. This phase transition correlates with an important phase transition previously observed in electrical conductivity versus temperature measurements. The existence of additional satellite reflections close to the regions of reciprocal space was found to be typical of all (Ba_1−xLa_x)₂In₂O_5+x specimens, although their intensity relative to the parent Bragg reflections systematically reduces as x increases. As x increases beyond 0.2, the -type satellite reflections initially become weaker and rather more diffuse for x=0.3 before splitting into pairs of rather weak and somewhat diffuse incommensurate satellite reflections for x=0.4 and beyond. An interpretation in terms of oxygen vacancy ordering and associated structural relaxation is given. Additional structured diffuse scattering is also observed and a tentative explanation in terms of Ba/La ordering and associated local strain distortions put forward.     

Synthesis and characterization of conductive polyaniline/TiO2 composite nanofibers

Fibrillar conductive polyaniline/TiO₂ (PANI/TiO₂) nanocomposites with different TiO₂ amount were synthesized with a template-free in situ polymerization method and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and conductivity measurement. The morphology determination shows that the PANI/TiO₂ composite nanofibers are relatively uniform with the diameter and length in the range of 20–40 nm and 390–420 nm respectively. It also shows that the TiO₂ of the composite is rutile crystalline and PANI has some degree of crystallinity. The IR measurement indicates that there is a strong interaction between the PANI and TiO₂ nanoparticles, and it has a beneficial effect on the thermal stability of the composite nanofiber. The conductivity of PANI/TiO₂ composites changes with TiO₂ amount and reaches an optimum value of 2.86 S/cm at 11.1 wt% TiO₂. Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(4): 67–70 (in Chinese)     

闭式十氢十硼酸盐的制备及其固体电解质应用研究进展

全固态电池是一种具有前景的电化学储能装置,它可以克服传统有机液体电解质电池的多方面不足,包括电解质易泄漏、稳定性低、易燃和能量密度有限等问题。固态电解质是全固态电池的重要组成部分,开发具有高离子电导率和宽电化学稳定性窗口的固体电解质是研制高能量和高功率密度全固态电池的关键问题之一。硼氢化物基固态电解质作为一类新型电解质,因具有高离子电导率、高热稳定性和低密度等优势而受到了广泛关注。其中,闭式十氢十硼酸碱金属盐是代表性材料之一。自1959年B₁₀H₁₀^2-被发现以来,其合成方法、结构与应用开发都得到了广泛研究。近年来其在固态电解质方面的研究证实,M₂B₁₀H₁₀（M=Na、Li等）及其衍生物具有高离子电导率、高热稳定性和化学稳定性、高电位窗口等特性,是一类颇具前景的固态电解质材料。本文主要综述了B₁₀H₁₀^2-合成方法及其在固态电解质方面的应用研究进展,并对今后B₁₀H₁₀^2-作为固态电解质的发展方向提出了展望。     

高负载量丝光沸石/堇青石整体式催化剂的原位合成和表征

采用原位合成法制备了高负载量的丝光沸石/堇青石整体式催化剂，考察了晶种添加、晶化方式(静/动态)和投料硅铝比等因素的影响，通过称重计算了丝光沸石负载量，并结合XRD，SEM等表征手段对其结晶状况和形貌进行了分析。结果表明，原位合成可有效制备高负载量(最高可达47.4%)的丝光沸石/堇青石整体式催化剂。晶种添加有利于提高丝光沸石负载量。静态晶化负载量一般高于动态晶化，但动态晶化方式则有利于更高水硅比条件下丝光沸石的生成。投料硅铝比和晶化方式的协同作用，共同影响分子筛负载量和形貌。     

Raman spectroscopic study of the hydration of short-chain poly(oxyethylene)s C <Subscript>1</Subscript>E<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>C <Subscript>1</Subscript> (<Emphasis Type="Italic">n</Emphasis>=1−4)

The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O−H stretching region for four short-chain POEs (C ₁E _n C ₁ withn=1−4). Excellent coincidence of the O−H stretching Raman band for all four POEs studied in the range of mole ratio H₂O/O _ether from 25 to 0.6 was observed, thus confirming the assumption stated above. A conclusion that all ether oxygen atoms in the POE molecule participate in hydrogen bonding with water molecules has been made.     

Conductivity Studies of <Emphasis Type="Italic">n</Emphasis>-Tetrabutylammonium Tetraphenylborate in 3-Pentanone in the Temperature Range from 283.15 to 329.15 K

The molar conductivities (Λ) of solutions of n-tetrabutylammonium tetraphenylborate (NBu₄BPh₄) in 3-pentanone have been measured in the temperature range from 283.15 to 329.15 K. The conductance data have been analyzed using the Lee-Wheaton conductivity equation with the distance parameter (a) set at Bjerrum’s pairing distance, and the limiting molar conductivities (Λ_o) and the association equilibrium constants (K _A) have been derived. The limiting ion conductivities (λ_±^o) have been evaluated according to the method of Krumgalz. The λ₊ ^o values have been compared with λ₊ ^o values calculated from the empirical equation of Gill. The thermodynamic functions, Gibbs energy (Δ G _A ^o), enthalpy (Δ H _A ^o) and entropy (Δ S _A ^o) for the process of ion-pair formation as well as the activation energy of the ionic movement (ΔH ^∗) have been evaluated. The obtained results are discussed in terms of ion-ion and ion-solvent interactions.     

Complexes of rare-earth metals with meconic acid

Two series of complexes of meconic acid (H₃ Mec) with rare-earths have been prepared by varying the preparative procedure. The compounds have the general formulae, [Ln(Mec) (H₂O)₂]·3 H₂O (whereLn=La, Ce, Pr, Nd, Sm, Ho and Y) and [Ln(HMec) (H₂ Mec) (H₂O)₂]·4 H₂O (whereLn=La, Pr, Nd and Sm). The infrared spectral data indicate that the carboxylate groups are bound to the rare-earth metal in a bidentate fashion. Thermal studies indicate that two water molecules are coordinated in each case. The complexes are probably polymeric.

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Komplexe von Seltenerd-Metallen mit Meconsäure

Zusammenfassung Es wurden zwei Reihen von Komplexen der Meconsäure (H₃ Mec) mit Seltenerd-Metallen mit den allgemeinen Formeln [Ln(Mec)(H₂O)₂]·3 H₂O (Ln=La, Ce, Pr, Nd, Sm, Ho, Y) und [Ln(HMec)₂(H₂ Mec) (H₂O)₂]·4 H₂O (Ln=La, Pr, Nd, Sm) hergestellt. Die IR-Spektren zeigen, daß die Carboxylat-Gruppen in zweizähniger Weise mit den Metallionen koordinieren; thermische Untersuchungen ergeben, daß in beiden Reihen jeweils zwei Wassermoleküle zusätzlich koordiniert sind. Die Komplexe weisen wahrscheinlich eine Polymerstruktur auf.

     

Synthesis, in situ spectroelectrochemical, in situ electrocolorimetric and electrocatalytic investigation of brown-manganese phthalocyanines

α- and β-substituted tetrakis(6-hydroxyhexylthiol) phthalocyaninato manganese (III) chloride complexes have been prepared via cyclotetramerization. Both complexes have been characterized by elemental analysis, FTIR, MS and UV–Vis spectral data. The voltammetric and in situ spectroelectrochemical studies reveal that both complexes exhibit an oxidation and three reduction processes having reversible, one-electron, and diffusion controlled mass transfer characteristics, which are assigned to Mn^IIIPc²⁻/Mn^IVPc²⁻, Mn^IIIPc²⁻/Mn^IIPc²⁻, Mn^IIPc²⁻/Mn^IPc²⁻, and Mn^IPc²⁻/Mn^IPc³⁻ couples respectively. The existence of oxygen in solution significantly affects the in situ spectroelectrochemical behavior of the complexes due to the formation of μ-oxo MnPc species. An in situ electrocolorimetric method has been applied to investigate the colors of the electro-generated anionic and cationic forms of the complexes for the first time in this study. The complexes, coated on a glassy carbon electrode potentiostatically, show considerable high electrocatalytic activity to hydrogen evolution reactions in aqueous solution.     

Thermotropic Liquid Crystals of Double-Chain Zwit-terionic Surfactants (C16)2NCnS

A series of double-chain sulfobetain zwitterionic surfactants with varying carbon number of the intercharge group (spacer), (C₁₆H₃₃)₂NCH₃(CH₂)_nSO₃, where n=2, 3, 4, and 6, referred to as (C₁₆)₂NC_nS, were synthesized. The influence of the spacer length on the thermal behaviors of (C₁₆)₂NC_nS in their pure state was studied using thermogravimetry (TG), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD). Thermogravimetric analysis (TGA) showed that the thermal stability of (C₁₆)₂NC_nS lowered with increasing the spacer length. All compounds showed a complex polymorphism. Only for (C₁₆)₂NC₄S and (C₁₆)₂NC₆S, thermotropic liquid crystals were observed using POM. The former exhibited a smectic A (SmA) phase, whereas the latter formed a hexagonal columnar phase. These liquid crystals obtained both in the cooling and the second heating scans provided compelling evidence for the thermal stability of these compounds.     

Asymmetrische Hg(II)-Komplexe mit Organothiolato- bzw. Organoselenolato-und Triazenato-Liganden

The mixed mercury complexes (2XC₆H₄)₂N₃HgY (X=CH₃, F, Cl, Br, I;Y=SC₂H₅, SC₆H₅, SeC₆H₅) have been prepared. Both the Hg–S and Hg–Se bonds and, in contrast to other mixed triazenato-mercury compounds, the triazenato-mercury bonds have been shown to be kinetically labile on the NMR time scale by means of⁷⁷Se and¹⁹⁹Hg NMR spectroscopy. Evidence has been obtained for the presence of (2XC₆H₄)₂N₃HgY together with HgY ₂ and [(2XC₆H₄)₂N₃]₂Hg in solution.