Search Results
Abstract
Solubility and pH precipitation studies were carried out to obtain the binuclear complex {[TiO(C9H6NO)2][Sn(C9H6NO)2]} involving 8-hydroxyquinoline as chelating agent. The compound, the individual mononuclear complexes and their physical mixture were evaluated by means of techniques such as TG, DTA, elemental analysis, X-ray diffraction, IR spectroscopy. The properties of the original compounds and also the thermoanalytical conditions exerted a great influence on the degree of crystallinity and on the crystalline phase of the mixed oxide obtained as final product of the thermal decomposition.
Abstract
The [MoOC1(dppe)2]Cl complex [dppe=(C6H6)2P(CH2)2 P(C6H5)2] was successfully examined in a process of reduction of molecular nitrogen in 
-radiation field. Yields of ammonia produced in this process were measured as a function of the Mo(IV) complex concentration and dose.
Complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 4-chloro-2-methoxybenzoic acid anion
Physico-chemical properties
Abstract
The complexes of 4-chloro-2-methoxybenzoic acid anion with Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ were obtained as polycrystalline solids with general formula M(C8H6ClO3)2 nH2O and colours typical for M(II) ions (Mn – slightly pink, Co – pink, Ni – slightly green, Cu – turquoise and Zn – white). The results of elemental, thermal and spectral analyses suggest that compounds of Mn(II), Cu(II) and Zn(II) are tetrahydrates whereas those of Co(II) and Ni(II) are pentahydrates. The carboxylate groups in these complexes are monodentate. The hydrates of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) heated in air to 1273 K are dehydrated in one step in the range of 323–411 K and form anhydrous salts which next in the range of 433–1212 K are decomposed to the following oxides: Mn3O4, CoO, NiO and ZnO. The final products of decomposition of Cu(II) complex are CuO and Cu. The solubility value in water at 293 K for all complexes is in the order of 10–3 mol dm–3. The plots of χM vs. temperature of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) follow the Curie–Weiss law. The magnetic moment values of Mn2+, Co2+, Ni2+ and Cu2+ ions in these complexes were determined in the range of 76−303 K and they change from: 5.88–6.04 μB for Mn(C8H6ClO3)24H2O, 3.96–4.75 μB for Co(C8H6ClO3)25H2O, 2.32–3.02 μB for Ni(C8H6ClO3)25H2O and 1.77–1.94 μB for Cu(C8H6ClO3)24H2O.
Abstract
In order to obtain cobalt oxides nanoparticles we have used the thermal decomposition of some carboxylate type precursors. These precursors were obtained by the redox reaction between cobalt nitrate and ethylene glycol, either bulk or dispersed in silica matrix. The redox reaction takes place by heating the Co(NO3)2·6H2O-C2H6O2 solution or the Si(OC2H5)4-Co(NO3)2·6H2O-C2H6O2 gels. Thermal analysis of the Co(NO3)2·6H2O-C2H6O2 solution and Si(OC2H5)-Co(NO3)2·6H2O-C2H6O2 gels allowed us to establish the optimal value for the synthesis temperature of the carboxylate precursors. By fast heating of the solution Co(NO3)2·6H2O-C2H6O2, the redox reaction is immediately followed by the decomposition of the precursor, which represents an autocombustion process. The product of this combustion contains CoO as unique phase. We have obtained a mixture of CoO and Co3O4 by annealing the synthesized carboxylate compounds for 2 h at 400°C. With longer annealing time (6 h), we have obtained Co3O4 as unique phase. The XRD study of the crystalline phases resulted by thermal decomposition of the precursors embedded in silica matrix, showed that the formation of Co2SiO4 and Co3O4, as unique phases, depends on the thermal treatment.
Abstract
The coal sample of the Shivee Ovoo deposits has been non-isothermally pyrolysed in a thermogravimetric analyser to determine the influence of temperature, heating rate and purge gas employed on the thermal degradation of the sample. The heating rates investigated in the TG were 10–50 K min–1 to final temperature of 1000C. N2or CO2 were employed as well as type of purge gas on the process of thermal degradation of the coal sample. The coal was also investigated in a fixed bed reactor to determine the influence of temperature and heating rate of the pyrolysis on the yield of products and composition of the gases evolved. The main gases produced were H2, CH4, C2H2, C2H4, C2H6, C3H6 and C3H8 and also minor concentrations of other gases.
Abstract
Complexes of lanthanide(III) (La–Lu) and Y(III) with 1-hydroxy-2-naphthoic acid were obtained as crystalline compounds with a general formula Ln[C10H6(OH)COO]3⋅nH2O:n=6 for La–Tm and Y, n=2 for Yb and n=0 for Lu. IR spectra of the prepared complexes were recorded, and their thermal decomposition in air were investigated. Spectroscopic data suggest that in the coordination of metal-organic ligand only oxygen atoms from the carboxylate group take part. When heated, the complexes decompose to the oxides Ln2O3, CeO2, Pr6O11 and Tb4O7 with intermediate formation of Ln(C11H7O3)(C11H6O3).
Abstract
Tin(II) complexes with 8-hydroxyquinolinate in solid state have been obtained by adding aqueous ammonium to a solution containing stannous chloride and 8-hydroxiquinoline in medium of HCl and acetone up to pH 5 and 9, respectively. The products obtained show the same composition, Sn(C9H6ON)2; however there are some differences regarding both the thermal behaviour in an oxidant atmosphere and morphology. These products were characterised by elemental and complexometric analysis, TG and DTA curves, infrared and X-ray diffractometry. TG curves show, above 448 K, the partial oxidation on air atmosphere of Sn(II) complexes to Sn(IV) complexes, SnO(C9H6ON)2. This behaviour does not depend only on pH in which the compounds were obtained but also on the heating rate in TG curves. Sn(II) complexes volatilise almost completely on nitrogen atmosphere and partially on air atmosphere depending on the oxidation degree of the compound.
Abstract
The rigid dopamine analogue (+/-) 6,7-ADTN was originally synthesized to probe the geometrical constraints of the dopamine receptor family and [3H] (+/-) 6,7-ADTN was required for receptor binding assay. The radioligands was prepared by means of catalytic tritium dehalogenation of a suitable dibromo precursor and characterized by HPLC and tritium NMR. It has proven very useful as a tool to study dopaminergic receptors.
Abstract
Several two and three parameter analytical functions were fitted to the measured detection efficiencies (
) of a Ge detector for a Marinelli beaker filled with samples up to different heights (H). From these, the expression =308E
–0.82/((H–6.1)2+107), gave the best fit. The measured and calculated efficiencies were compared and for 70 determinations, a relative standard deviation of only 7.6% was obtained.
Abstract
A preconcentration method combined with neutron activation technique for the analysis of organic and inorganic mercury in waste water samples at ppb levels is presented. The inorganic mercury is extracted in CCl4 solution with lead diethyldithiocarbamate reagent and the organic mercury is extracted in C6H6 solution. Interfering activities of sodium and bromine are removed from the irradiated samples by this procedure. Two different solvent extraction procedures are also described in detail.
