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991.
HoClTe2O5: A Telluriumdioxide‐rich Holmium(III) Chloride Oxotellurate(IV) While attempting to synthesize anionically derivatized holmium oxotellurates by reacting holmium chloride (HoCl3) with tellurium oxide (TeO3; molar ratio 1 : 3, 800°C 10 d) in evacuated silica ampoules, transparent, greenish yellow and coarse single crystals of holmium(III) chloride oxotellurate(IV) HoClTe2O5 (triclinic, P1; a = 762.07(6), b = 796.79(6), c = 1010.36(8) pm, α = 100.987(4), ß = 99.358(4), γ = 91.719(4)°; Z = 4) were obtained. The crystal structure contains eightfold coordinated (Ho1)3+ (only surrounded by oxygen atoms) and sevenfold coordinated (Ho2)3+ cations (surrounded by one chloride and six oxide anions). Each sort of holmium polyhedra convenes independently to chains along [100] by edge‐sharing which again combine alternately via O6 and O9 to form 2{[Ho2O10(Cl1)]15—} layers parallel (001). Each of the four crystallographically different Te4+ cations are surrounded by three close oxygen atoms (d(Te—O) = 188 — 195 pm) and always one more situated further away. The stereochemical activity of the non‐bonding electron pairs (“lone pairs”) leads to ψ1‐trigonal bipyramidal coordination figures. The ψ1‐tetrahedral [TeO3]2— basic units form discrete [Te2O5]2— doubles with ecliptic conformation which are arranged in a fish‐bone pattern parallel to (001) on both sides of the 2{[Ho2O10Cl]15—} layers. The coherence of the 2{[Ho2(Cl1)Te4O10]+} layers is exclusively maintained via Cl2—Te1 contacts with an extraordinary long distance of 335 pm. As (Cl1)— belongs to the coordination sphere of (Ho2)3+ and (Cl2)— is only surrounded by Te4+, the compound should be correctly named holmium(III) chloride oxochlorotellurate(IV) Ho2Cl[Te4O10Cl] (Z = 2). 相似文献
992.
The effect of 60Co γ-irradiation on aqueous solutions of poly(N-vinyl-2-pyrrolidone) (PVP) in the presence of persulfate anion has been investigated. The gelation dose of PVP and persulfate containing PVP aqueous solutions has been determined. At low concentrations of persulfate (1.00–3.50%), gelation percentages exhibited a decreasing trend by increasing persulfate content in aqueous solutions of the polymer. The gelation doses of persulfate containing polymer solutions were calculated by the Charlesby–Pinner equation. It was observed that the gelation dose values were shifted to higher values by increasing persulfate concentration in solution. The ratio of the chain scission and crosslinking yields (G(s)/G(x)) was also determined. The results showed that the G(s)/G(x) ratios were smaller than one for PVP aqueous solution system, whereas those obtained for persulfate containing PVP aqueous solutions were higher than unity. The results implied that the chain scission of polymer is more effective than crosslinking in the presence of persulfate. Mechanism of the crosslinking and/or degradation and structure–property relationship of PVP and PVP/persulfate hydrogel systems were investigated by Fourier transformation infeared and thermal analysis (differential scanning calorimetry, thermal gravimetric analysis and differential thermai analysis) methods. 相似文献
993.
C. S. Bentivoglio Ruiz L. D. B. Machado J. E. Volponi E. Segura Pino 《Journal of Thermal Analysis and Calorimetry》2004,75(2):507-512
Radiation curing is an environmentally-friendly technology. Furthermore, radiation curing is a faster, energy saving and more
efficient industrial process than the heat-curable process. One of the most important requirements for the widespread application
of UV curable coatings in the coating industry is that they are stable vs. atmospheric degradation. Today's state of the art
in oxidative drying and thermosetting coatings is the use of light stabilizers to protect polymers vs. the damage of outdoor
exposure. Oxygen has a detrimental effect on the cure response of free radical systems, especially in thin-film coatings.
Differential photocalorimetry (photo-DSC) was used to investigate the oxygen effect and the use of light stabilizers on UV
curing of photocurable formulations based on acrylate materials. Coating thickness influence was also considered.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
994.
E. Lukevics L. Ignatovich I. Sleiksha V. Romanov S. Grinberga J. Popelis I. Shestakova 《Chemistry of Heterocyclic Compounds》2007,43(2):143-150
A new method was developed for the synthesis of silicon-and germanium-containing acetylfurans and acetylthiophene by metallation
of 2-acetylfuran or 2-acetylthiophene with n-BuLi at low temperature after protection of the carbonyl group with lithium N-methylpiperazide
and reaction of the lithium derivative with various trialkyl-, alkylphenyl-, and cycloalkylchlorosilanes or trialkylchloro(bromo)germanes.
The cytotoxic activity of the new compounds was studied, and it was established that the silicon-and germanium-containing
acetylfurans and acetylthiophenes are substances with low toxicity (LD50 312->2000 mg/kg) and have low cytotoxicity toward HT-1080 and MG-22A tumor cells.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 192–199, February, 2007. 相似文献
995.
HUANG Wei-Ping ZHANG Xin-Jie WU Shi-HuaMA Shu-Yin ZHANG Shu-Ji ZHAO Wei-Jun 《天然气化学杂志》1997,6(3):252-257
IntroductionIn1962,N.V.Kutepow'SgroupfirstusedcomplexesofFe,CoandNiascatalyststocatalyzecarboXylationofethanoltopreparepropanoicacidanditsderivants.Thereactionpressurewashighandtheyieldwaslow.LateronPaulalsandhiscolleagueusedabC13andiodineascatalyst,which… 相似文献
996.
The mercury perrhenates with the empirical formulas HgReO4 and Hg2ReO5 were prepared by annealing powdered mixtures of mercury(II)oxide and mercury(II)metaperrhenate Hg(ReO4)2 in sealed silica tubes. Their crystal structures were determined from single-crystal X-ray data. HgReO4 crystallizes dimeric with nearly linear O3Re? O? Hg? Hg? O? ReO3 molecular units and Hg2ReO5 has a solid state structure, where Hg(I) and Hg(II) together with oxygen atoms form 14-membered rings, which are condensed to two-dimensionally infinite polycationic nets of composition (Hg22+ · 2 HgO)n. These nets are separated from each other by tetrahedral ReO4? anions. 相似文献
997.
A new copper(Ⅱ) compound with imino nitroxide radicals [Cu(IM-MeImz)2]·(SCN)2 (IM-meImz =2-(5-methylimidazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl) has been synthesized and characterized structurally and magnetically. It crystallizes in monoclinic, space group P21/c with a = 9.3604(7), b = 10.3012(7), c = 16.6684(12) (A), β = 105.0290(10)°, V = 1552.25(19)(A)3, C24H34CuN10O2S2, Mr = 622.27, Z = 2, Dc = 1.331 g/cm3, μ(MoKα) = 0.876 mm-1, F(000) =650, the final R = 0.0374 and wR = 0.1079. X-ray analysis demonstrates that the IM-MeImz ligand is coordinated to the copper(Ⅱ) ion as an unusual didentate chelate with a κ2 N(MeImz),O(IM) mode in the complex. The square-planar coordination sites at Cu(Ⅱ) are occupied by two O and two N atoms from the imino nitroxide radicals. The complex molecules are connected as a onedimensional polymer structure by intermolecular interactions. Magnetic measurements show that there are intramolecular antiferromagnetic interactions between the Cu(Ⅱ) ion and radicals. 相似文献
998.
Jainamma Mathew Venkatanarayana Mahadevan 《Journal of polymer science. Part A, Polymer chemistry》1995,33(16):2803-2812
Oxidation of ferrous orthophenanthroline (FeP) by peroxydiphosphate (PP) in aqueous medium at pH 1 was followed spectrophotometrically. Kinetic analysis has shown that oxidation occurs via the formation of an intermediate complex between FeP and PP. Equi-librium and rate constants were calculated. Influence of surfactants on the oxidation of FeP by PP was also Investigated. The equilibrium constant for complex formation was found to be higher in the presence of surfactants. The enhanced complex formation has been attributed to the ionic interactions between the charged surfactant and the ionic species in the reaction medium. Polymerization of HEMA initiated by the redox system,FeP/PP, was carried out in aqueous medium, under the conditions of excess reductant over oxidant and excess oxidant over reductant. The polymerization followed different mech-anisms under these conditions; with excess oxidant, the growing polymer radicals underwent oxidative termination, while with excess reductant, primary radical termination was pre-ferred. The effect of surfactants on the aqueous polymerization of HEMA using the redox system FeP/PP was also investigated. In addition to the decrease in rate, the polymerization followed a different mechanism in the presence of surfactants, the growing radicals ter-minated by mutual interaction. © 1995 John Wiley & Sons, Inc. 相似文献
999.
固体氧化物电解池是一种高效、环境友好型的能量转换器件,可以直接将电能转化为化学能. 本文介绍了近年来作者课题组在固体氧化物电解池直接用于CO2还原的研究进展,并以阴极材料为主着重讨论了金属陶瓷电极和混合导电型钙钛矿氧化物电极的研究工作,最后展望了未来固体氧化物电解池直接电解CO2的研究思路和方向. 相似文献
1000.
Zhenbin Niu Xingyuan Zhang Jiabing Dai Heping Zhang 《Frontiers of Chemistry in China》2007,2(2):151-155
A new kind of ultraviolet (UV) curable waterborne polyurethane acrylate dispersion was synthesized based on hydroxyl-terminated
polybutadiene (HTPB), poly-(propylene glycol) (PPG), isophorene diisocyanate (IPDI), 2-hydroxy ethyl acrylate (HEA) and dimethylol
propionic acid (DMPA) after neutralizing by triethylamine (TEA). 2-Hydroxy-1-[4-2-hydroxyethoxy) phenyl]-2-methyl-1-propanone
(Irgacure 2959) was used as a photoinitiator and deionized water as a diluent. Fourier transform infrared (FTIR) analysis
was used to identify the chain structure of the UV-curable polyurethane prepolymer based on HTPB and the curing process. Effects
of relative content of HTPB and PPG on emulsion stability, resistance to water and ethanol, thermal stability, compatibility
of soft and hard segment, as well as the mechanical property of the cured film were investigated.
Translated from Polymer Materials Science and Engineering, 2006, 22(3): 199–203 (in Chinese) 相似文献