Tetranuclear copper(II) complex with the µ<Subscript>4</Subscript>-1,6-hexadicarboxylate linker: crystal structure and magnetic properties

Tetranuclear copper(II) complex [Cu₄L₂(OOC(CH₂)₆COO)] (I) based on bis(azomethine), condensation product of 1-phenyl-3-methyl-4-formylpyrazolone-5 with 1,3-diaminopropanol-2, is synthesized. The structure of its DMSO-adduct (Ia) is determined by X-ray diffraction analysis (CIF file CCDC 1447891). The complexes contain two binuclear fragments bonded by the µ₄-1,6-hexadicarboxylate linker. The magnetic exchange interaction in complex I is antiferromagnetic (2J =–155 cm^–1), whereas that in complex Ia is ferromagnetic (2J = 129 cm^–1), which is due to different conformations of the metallochelate cycles.     

Modification of biologically active amides and amines with fluorine-containing heterocycles 12.* Endo- and exocyclic modifications of the drug riluzole with trifluoromethyl-containing heterocycles

New derivatives of the drug riluzole, 6-(trifluoromethoxy)benzothiazol-2-ylamine, modified at the endo- and exocyclic nitrogen atoms with trifluoromethyl-containing heterocycles were synthesized via transformations of methyltrifluoropyruvate and hexafluoroacetone N-6-(trifluoromethoxy)benzothiazol-2-ylimines by meams of cycloaddition and cyclocondensation reactions, respectively. The influence of the resulting compounds on neuronal NMDA receptors, as well as on the release and reuptake of the neurotransmitter glutamate was investigated.     

Influence of medium viscosity on photophysical properties of kynurenic acid and kynurenine yellow

Dependences of the fluorescence and triplet state quantum yields of kynurenic acid (1) and kynurenine yellow (2) in water—glycerol mixtures on medium viscosity have been studied. The main channel of the singlet excited state decay of compound 1 is the intersystem crossing, which rate weakly depends on the viscosity; only a small (approximately 1.5-fold) increase in the fluorescence yield was found for this compound with the increase of the solution viscosity from 0.84 cP (aqueous solution) to 78 cP (86% glycerol). The deactivation of the S₁ state of compound 2 is caused mainly by the internal conversion, and a noticeable increase of the fluorescence yield (approximately 3-fold), as well as the change in the photolysis product yields, was observed with the increasing percentage of glycerol in the mixture. The triplet state quantum yields for compounds 1 and 2 remained unchanged with the variation of the glycerol content in the mixture.     

用单颗粒气溶胶质谱研究海宁市秋、冬季PM_(2.5)化学组成及来源

对海宁市区PM_(2.5)来源进行分析,分别于2016年11月11日~24日以及2016年12月13日~21日期间,使用单颗粒气溶胶质谱仪(SPAMS)在海宁市环境保护监测站点位进行了为期14天和8天的定点监测,分别代表了秋季和冬季的监测结果。结果表明,监测期间海宁市总体空气质量较好,优、良天气占比为75.8%。海宁市首要污染物为机动车尾气源,燃煤源次之,工业源排在第三位。整体来看,监测期间PM_(2.5)质量浓度的升高大多伴随着燃煤及机动车尾气占比的同步升高。秋、冬季的重度污染过程与燃煤源和机动车尾气源的升高有关,其中秋季的燃煤源贡献高峰可能与监测点位西北方向的气团传输有关。     

Thermodynamic study of Ag<Subscript>8</Subscript>GeSe<Subscript>6</Subscript> by EMF with an Ag<Subscript>4</Subscript>RbI<Subscript>5</Subscript> solid electrolyte

The Ag–Ge–Se system was studied in the range of compositions Ag₂Se–GeSe₂–Se by measuring the EMF of the concentration (relative to the silver electrode) circuits with a solid electrolyte Ag₄RbI₅ in the temperature range 290–430 K. The polymorphic transition temperature of Ag₈GeSe₆ (320 K) was determined and the partial molar functions of silver were calculated for both crystal modifications of this compound based on the EMF measurements. The thermodynamic functions of formation and entropy of both modifications of Ag₈GeSe₆ and the thermodynamic functions of its polymorphic transition were calculated.     

The Role of Interphase Interactions in Electrosynthesis of Composites Based of Graphene Oxide and Poly-<Emphasis Type="Italic">o</Emphasis>-Phenylenediamine

The formation of the composite of reduced graphene oxide (RGO) with poly-o-phenylenediamine (PPD) on the surface of SnO₂-coated conducting glasses (CG) is studied by the methods of voltammetry, atomic force microscopy (AFM), electron microscopy (SEM) with energy-dispersive X-ray spectroscopic (EDXS) microanalysis, and electron spectroscopy, When a CG with deposited graphene oxide is placed into aqueous solution of o-phenylenediamine (OPD), the monomer is strongly fixed in the GO matrix, as confirmed by EDXS data. The further redox interaction in the two-phase system GO–OPD initiates polymerization of OPD in the GO film. When anodic polarization in switched on, the oxidation and the further polymerization of OPD go on, while GO is reduced to RGO as a result of mediated reaction to yield the RGO–PPD composite even in the absence of cathodic polarization. The electron spectra of composites reveal the presence of an absorption band close to absorption of individual PPD. According to AFM and SEM data, OPD incorporated into the composite structure keeps RGO from being folded in acidic media. As the time of impregnation increases, the degree of reduction of GO to RGO changes, which is reflected in the surface morphology and the amount of monomer in the composite (RGO–PPD)-1. The coating becomes black, which is typical of RGO, and its conductivity increases by 4–5 orders of magnitude.     

Regularities of oxygen and water thermal desorption from barium cerate doped by neodymium,samarium, and gadolinium

Processes of thermal desorption of oxygen molecules and water from BaCe_1–x M _x O_3–δ, where M= Nd, Sm, and Gd, presintered in air at the temperature of 650°C are studied. It is found that oxygen is desorbed only from neodymium–doped barium cerate and is almost not evolved from barium cerate doped by samarium and gadolinium. The amount of desorbed oxygen features a square dependence on cationic doping by neodymium. At similar degrees of cationic doping, the amount of water desorbed from neodymium–doped barium cerate is always lower than that from the cerate doped by samarium and gadolinium. The obtained experimental data on thermal desorption and analysis of literature data served as a basis for the conclusion as to the mixed valency of neodymium Nd(III)–Nd(IV) in BaCe_1–x Nd _x O_3–δ. In this case, at similar doping degrees x, the hydration degree of BaCe_1–x Nd _x O_3–δ is lower and the oxygen index is higher than in BaCe1_–x (Sm,Gd) _x O_3–δ. The differences become more pronounced at high degrees of cationic doping and must decrease at an increase in temperature.     

Synthesis of polymer nanocomposite ion-exchange membranes from sulfonated polystyrene and study of their properties

Methods for the preparation of composite ion-exchange membranes from polymer (polyvinylidene fluoride (PVDF), ultrahigh molecular weight polyethylene (UHMWPE), and polypropylene (PP)) matrices were considered. Polystyrene (PS) was introduced in the matrices by thermal polymerization of the monomer followed by sulfonation of the implant. The fundamentals of membrane synthesis from industrial polytetrafluoroethylene (PTFE, Teflon F-4) films by thermal polymerization of styrene in a film stretched in a monomer solution followed by sulfonation of incorporated PS were described. The literature on radiation- chemical synthesis of composite ion-exchange membranes based on polymer matrices with embedded polystyrene and its subsequent sulfonation was analyzed. Some problems of the kinetics and mechanism of thermal implantation of PS into various polymer matrices under different conditions were discussed. The physicochemical characteristics, structure, and transport properties of the membranes synthesized by thermal implantation of PS were reported. The obtained membranes were tested in low-temperature fuel cells.     

Composite electrode materials for solid oxide fuel cells with the protonic electrolyte of La<Subscript>1 – <Emphasis Type="Italic">x</Emphasis></Subscript>Sr<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>ScO<Subscript>3 – δ</Subscript>

Heterogeneous systems based on the proton–conducting oxide of La_0.95Sr_0.05ScO_{3 – δ} with Cu, Fe, Ni, Pd, La_0.9Sr_0.1MnO_{3 – δ} considered as potential materials of solid oxide fuel cell (SOFC) electrodes are synthesized. Chemical interaction between individual components of composite materials is studied, dependences of thermal and chemical expansion of the electrolyte and composites are obtained, conductivity of electrodes is measured under the conditions of SOFC operation.