234 resultados para cerium compounds
Resumo:
The extraction behavior of Ce(IV) along with Th(IV) and Ln(III) (Ln = Ce, Gd, Yb) nitrate by pure ionic liquid, [C(8)mim]PF6, was investigated. [C(8)mim]PF6 alone showed good extraction ability for Ce(IV), while it was slight for Th(IV) and negligible for Ln(III). The extraction behavior of Ce(IV) by [C(8)mim]PF6 was particularly studied, and the most probable extraction mechanism proposed was the anion exchange mechanism. Moreover, the stripping of Ce(IV) from IL phase was also investigated. The Ce(IV) in IL phase can be quantitatively recovered by water.
Resumo:
The effect of combination between a trace of halogenated compounds (such as ferric chloride and ammonium bromide) and Ni2O3 particles on the carbonization of polypropylene (PP) was investigated during combustion. The results showed a synergistic catalysis of combined halogenated compounds with Ni2O3 in promoting the formation of the residual char during combustion. The investigation on the promotion mechanism showed that halide radical releasing from halogen-containing additives worked as a catalyst to accelerate dehydrogenation-aromatization of degradation products of PR which promote the degradation products to form the residual char catalyzed by nickel catalyst.
Resumo:
Two 3d-4f heterometallic compounds of p-tert-butylsulfinylcalix[4] arene were synthesized by the solvothermal method and characterized by some hinged double-dumbbell-like subunits in which two perpendicular dumbbell entities were constructed by an in-between isosceles triangle Mn(II)Ln(2)(III), and two tail-to-tail calixarene molecules, and hinged by the lanthanide-sulfinyl group bonding. The magnetic properties of the title compounds were examined.
Resumo:
Five new compounds of sulfonylcalix[4]arenetetrasulfonate (SC4AS), [H7Na(H2O)(3)(SC4AS)(phen)(5)](H2O)(11.9) (1), [H6Mn(H2O)(4)(SC4AS)(phen)(5)] (H2O)(12.7) (2), [Cu-4(SC4AS) (phen)(6)] (H2O)(4.5) (3), {[Cu (2)(SC4AS) (bpy)(2)][Cu(bpy)(2)(H2O)](2)} (H2O)(6.6) (4), and {[Zn-2(SC4AS) (phen)(2)][Zn(phen)(2)(H2O)(2)](2)} (H2O)(7) (5) (where phen 1,10-phenanthroline and bpy = 2,2'-bipyridine), were synthesized by a hydrothermal method and structurally determined by single crystal X-ray diffraction. The SC4AS ligand adopts partial cone conformation in compounds 1 and 2 and 1,2-alternate form in compounds 3-5. According to the structural analysis and density functional theory (DFT) calculations, we suggest that the metal can affect the conformation of SC4AS.
Resumo:
Seven supramolecular compounds comprising p-sulfonatocalix[6]arene and transition metals, {[Cu(Imz)-(phen)(H2O)](4)[C6AS]}center dot 10H(2)O (1), {[Cu(Imz)(2)(phen)](2)[Cu(Imz)(phen)(H2O)(2)](2)[C6AS]}center dot 13.3H(2)O (2), {[M(phen)(2)(H2O)]-[(M(phen)(2)](2)[C6AS]}center dot nH(2)O (3 and 4) (3: M = Co and n = 29.6; 4: M = Zn and n = 29.9), {[Cu(phen)(2)](4)[C6AS]}(2)center dot 13H(2)O (5), [H3O](2)[Co(phen)(3)](2)[C6AS]center dot 10.7H(2)O(6), and [Cu(phen)(2)(H2O)](2){[Cu(phen)(2)](2)[C6AS]}center dot 8H(2)O(7)(phen = 1,10-phenanthroline, C6AS = p-sulfonatocalix[6]arene, Imz = imidazole), have been synthesized by a hydrothermal method and structurally characterized by IR spectroscopy, thermogravimetric-differential thermal analysis (TG-DTA), and single crystal X-ray diffraction.
Resumo:
Two new copper-thiacalix[4]arene compounds, [Cu-2(1)-Cl-2(H(4)TC4A)](CH3OH) (1) and [Cu(I)2Cl(2)(H(4)PTC4A)](CH3OH)(CHCl3)(0.5) (2) (where H(4)TC4A = p-tert-butylthiacalix[4]arene and H(4)PTC4A = p-phenylthiacalix[4]arene), were synthesized by the solvothermal method in the mixed CH3OH/CHCl3 (1: 1) solvent and reassembled in air at room temperature to two other structures, [(Cu4Cl3)-Cl-II(HCO2)(TC4A)(CH3-OH)(2)(H2O)](CHCl3)(CH3OH)(2.7) (3) and [(Cu4Cl4)-Cl-II(PTC4A)(CH3OH)(4)] (4), respectively. All these four compounds were characterized by TG analyses, FTIR spectroscopy, and singlecrystal X-ray diffraction analyses. Compounds 1 and 2 feature two-dimensional layered networks, while compounds 3 and 4 are assembled by some tetranuclear units.
Resumo:
Starburst-substituted hexaazatriphenylene Compounds have been designed and synthesized by introducing various peripheral aryl substituents to the central heterocyclic core. The effects of various substituent groups on the photophysical and electrochemical properties of the substituted hexaazatriphenylene have been investigated. Significant red-shifts of the absorption peak (from 413 nm to 530 nm) and emission peak (from 432 nm to 700 nm) were observed when the electron-donating ability of the aryl substituents was increased, corresponding to a decrease in the band gap from 2.90 eV to 2.05 eV. Introducing bulky substituents with weak electron-donating ability enhances the fluorescence quantum yield from 23% to 87%. In contrast, incorporating aryl substituents with strong electron-donating ability decreases the fluorescence quantum yield.
Resumo:
Four transition-metal-amine complexes incorporating indium thioarsenates with the general formula M(tren)InAsS4 (M=Mn, Co, and Zn) and a noncondensed AsS33- unit have been prepared and characterized. Single-crystal X-ray diffraction analyses show that compound 1 (M=Mn) crystallizes in the triclinic crystal system (space group: P (1) over bar) and consists of a one-dimensional (1D) inorganic (1)(infinity){[InAsS4](2-)} chain and [Mn(tren)](2+) groups bonded to the opposite sides of an eight-membered In2As2S4 ring along the backbone of the infinite inorganic chains. Compounds 2 (M=Mn), 3 (M=Zn), and 4 (M=Co) are isomorphous molecular compounds. They all crystallize in the monoclinic crystal system (space group: P2(1)/c). The Mn2+ cation of [Mn(tren)](2+) in 1 has a distorted octahedral environment, while the transition-metal cations of [M(tren)](2+) in the other three compounds locate in trigonal-bipyramidal environments.
Resumo:
Pyrazoline derivatives have been used widely in dyeing industry as fluorescent whitening agents due to their excellent capability. According to Schellhammer theory of the relation between chemical structure and fluorescent quality, six new fluorescent compounds were designed and synthesized which contained the benzothiazole group in the I-pyrazoline, the indole group in the 3-pyrazoline and the derivatives of phenyl in the 5-pyrazoline. The structure of target compounds was confirmed by IR, H-1 NMR, MS and elementary analysis. The fluorescence spectra showed that these compounds had good fluorescence. They could absorb ultraviolet light at near 353 nm. The fluorescence maximum emission wavelengths were about 430-443 nm. It was a kind of promising fluorescence compounds. The largest fluorescence emission wavelength and the fluorescence intensity were related to the substituted group of the compounds. When the 6-Br group was introduced into benzothiazole, the fluorescence emission wavelength exhibited a blue shift, and the fluorescence intensity increased.
Resumo:
Four diboron-contained ladder-type pi-conjugated compounds 1-4 were designed and synthesized. Their thermal, photophysical, electrochemical properties, as well as density functional theory calculations, were fully investigated. The single crystals of compounds 1 and 3 were grown, and their crystal structures were determined by X-ray diffraction analysis. Both compounds have a ladder-type g-conjugated framework. Compounds I and 2 possess high thermal stabilities, moderate solid-state fluorescence quantum yields, as well as stable redox properties, indicating that they are possible candidates for emitters and charge-transporting materials in electroluminescent (EL) devices. The double-layer device with the configuration of [ITO/NPB (40 nm)/1 or 2 (70 nm)/LiF (0.5 nm)/Al (200 nm)] exhibited good EL performance with the maximum brightness exceeding 8000 cd/m(2).
Resumo:
BACKGROUND: Ionic liquids (ILs) as environmentally benign solvents have been widely studied in the application of solvent extraction. However, few applications have been successfully industrialized because of the difficult stripping of metal ions or the loss of components of the ILs. More work needs to be done to investigate the extraction behaviour of IL-based extraction systems. In this work, the extraction behaviour of Ce(IV), Th(IV) and some trivalent rare earth (RE) nitrates by di(2-ethylhexyl) 2-ethylhexylphosphonate (DEHEHP) in the IL, 1-methyl-3-octylimidazolium hexafluorophosphate ([C(8)mim]PF6), was investigated and compared with that in the n-heptane system. In particular, the effect of F(I) on the extraction mechanism for Ce(IV) and its separation from Th(IV) was investigated. Otherwise, the recovery efficiency of Ce(IV) and F(I) from a practical bastnasite leach liquor was examined using IL based extraction.
Resumo:
Die-cast Mg-4Al-4RE-0.4Mn (RE = Ce-rich mischmetal) and Mg-4Al-4La-0.4Mn magnesium alloys were prepared successfully and their microstructure, tensile and creep properties have been investigated. The results show that two binary Al-RE phases, Al11RE3 and Al2RE, are formed along grain boundaries in Mg-4Al-4RE-0.4Mn alloy, while the phase compositions of Mg-4Al-4La-0.4Mn alloy mainly consist of alpha-Mg phase and Al11La3 phase. And in Mg-4Al-4La-0.4Mn alloy the Al11La3 phase occupies a large grain boundary area and grows with complicated morphologies, which is characterized by scanning electron microscopy in detail. Changing the rare earth content of the alloy from Ce-rich mischmetal to lanthanum gives a further improvement in the tensile and creep properties, and the later could be attributed to the better thermal stability of Al11La3 phase in Mg-4Al-4La-0.4Mn alloy than that of Al11RE3 phase in Mg-4Al-4RE-0.4Mn alloy.
Resumo:
The solid solutions of CdYFeWO7, which are cubic pyrochlores of the type A(2)B(2)O(7), have been prepared and their structures were determined using Ab initio method. Rietveld refinement of the powder XRD data showed that CdYFeWO7 adopted cubic (Fd-3m) structure, while oxides crystallized in a defect-pyrochlore structure where both O (48f) and O'(8b) sites were partially occupied, and the frustrated cations sublattice precluded long range ordering of Fe/W in the pyrochlore structure. Charge distribution analysis also suggested incomplete occupation of different oxygen sites, thus the compound was non-stoichiometric, with the formula CdYFeW0.982O6.94, Magnetic measurements were carried out to find that Fe ions were in the high spin trivalent state. Curie Weiss paramagnetism down to similar to 5 K and the characteristic superposition between FC and ZFC suggested spin liquid rather than spin glass state.
Resumo:
A solution-phase approach to synthesize four kinds of mixed-valence, transition metal compounds nanotube is described. The approach is based on the self-assembly of siloxane sol. The resulted production of mixed-valence, transition metal compounds share a common structural characteristic of tubular geometrical morphology, at least for the ones we studied. The results demonstrate that the synthesis strategy can be a general route for preparation of compound nanotubes. In addition, the size control of nanotubular materials can be easily achieved through varying the ionic strength of solution. Based on the strategy, the diameters of ultrathin Ru-Fe nanotubes can be easily tuned between 100 nm and 800 nm.