Search Results
Abstract
4-Chloro-2-methoxybenzoates of light lanthanides(III) were obtained as mono-, di-or trihydrates with metal to ligand ratio of 1:3 and general formula Ln(C8H6ClO3)3·nH2O, where n=1 for Ln=Ce, Pr, n=2 for Ln=Nd, Sm, Eu, Gd and n=3 for Ln=La. The complexes were characterized by elemental analysis, IR spectra, thermogravimetric studies, X-ray diffraction and magnetic measurements. The carboxylate group appears to be a symmetrical bidentate, chelating ligand. All complexes seem polycrystalline compounds. Their thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which next are decomposed to the oxides of the respective metals. The solubilities of light lanthanide(III) 4-chloro-2-methoxybenzoates in water at 293 K are of the order of 10−5 mol dm−3. The magnetic moments were determined over the range of 77–300 K. They obey the Curie-Weiss law. The values of μeff calculated for all compounds are close to those obtained for Ln3+ by Hund and Van Vleck. The results indicate that there is no influence of the ligand field of 4f electrons on lanthanide ions and the metal ligand bonding is mainly electrostatic in nature.
Abstract
It is proposed to use 14 MeV neutrons tagged by the associated particle neutron time-of-flight technique (APnTOF) to identify the fillers of unexploded ordnances (UXO) by characterizing their carbon, nitrogen and oxygen contents. To facilitate the design and construction of a prototype system, a preliminary simulation model was developed, using the Geant4 toolkit. This work established the toolkit environment for (a) generating tagged neutrons, (b) their transport and interactions within a sample to induce emission and detection of characteristic gamma-rays, and (c) 2D and 3D-image reconstruction of the interrogated object using the neutron and gamma-ray time-of-flight information. Using the modeling, this article demonstrates the novelty of the tagged-neutron approach for extracting useful signals with high signal-to-background discrimination of an object-of-interest from that of its environment. Simulations indicated that an UXO filled with the RDX explosive, hexogen (C3H6O6N6), can be identified to a depth of 20 cm when buried in soil.
Manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes with 4-oxo-4H-1-benzopyran-3-carboxaldehyde
Thermal, spectroscopic and magnetic characterization
Abstract
The complexes Mn(II), Co(II), Ni(II) and Zn(II) with 4-oxo-4H-1-benzopyran-3-carboxaldehyde were synthesized and characterized by elemental analysis, infrared and UV spectroscopy, X-ray diffraction patterns, magnetic susceptibility, thermal gravimetric analysis, conductivity and also solubility measurements in water, methanol and DMF solution at 298 K. They are polycrystalline compounds with various formula and different ratio of metal ion:ligand. Their formula are following: [MnL2(H2O)](NO3)2·2H2O, [CoL2](NO3)2·3H2O, [NiL2](NO3)2·3H2O, [CuL2](NO3)2·H2O and [ZnL3](NO3)2, where L = C10H6O3. The coordination of metal ions is through oxygen atoms present in 4-position of γ-pyrone ring and of aldehyde group of ligand. Chelates of Mn(II), Co(II), Ni(II) and Cu(II) obey Curie–Weiss law and they are high-spin complexes with the weak ligand fields. The thermal stability of analyzed complexes was studied in air at 293–1,173 K. On the basis of the thermoanalytical curves, it appears that thermal stability of anhydrous analysed chelates changed following: Cu (423 K) < Zn (438 K) ~ Co (440 K) < Ni (468 K). The gaseous products of thermal decomposition of those compounds in air atmosphere are following: CO2, CO, NO2, N2O, hydrocarbons and in case of hydrates also water. The molar conductance data confirm that the all studied complexes are 1:2 electrolytes in DMF solution.
substitute for the traditional Chlorhydrin and Halcon processes [ 1 , 2 ]. Extensive efforts have been made to develop an alternative process for the direct epoxidation of C 3 H 6 using molecular oxygen as an oxidant. Especially, the approach combining
Thermal behaviour and electro-optical properties of a series of liquid crystals based on palladium complexes with mixed ligands
Schiff bases and N-benzoyl thioureas
, 6.3. 1 H NMR (300 MHz, CDCl 3 ): 8.12 (s, 1H), 7.74–7.51 (m, 12H), 7.42–7.34 (m, 5H), 7.22 (m, 2H), 7.03–6.98 (m, 4H), 6.90 (d, 1H, 4 J = 2.4 Hz), 6.60 (dd, 3 J = 8.4 Hz, 4 J = 2.4 Hz, 1H), 4.04 (m, 4H), 3.89 (s, 3H), 1
4 H 6 O 4 , Sigma-Aldrich) was used as a precursor of palladium and fullerite C 60 powder (99.99%, Sigma-Aldrich) was applied as a precursor of carbon. Both compounds were evaporated from two separated sources using electrical heaters. PVD
the MPW1PW91/6-31++G** theoretical level compared to the reactants and are given in Table 3 . The C 2 –H 6 and C 5 –H 11 bond distances increase, which implies breaking of this bond (1.095–1.01–1.497–1.539 Å) in the TSs. The C 2 –C 3 and C 4 –C 5
tin dioxide based catalysts was tested with a propylene oxidation reaction. The surface behavior and the activity in C 3 H 6 oxidation on SnO 2 /γ-Al 2 O 3 samples was compared with those of the corresponding support γ-Al 2 O 3 and bulk SnO 2 . The
.77 (m); 6.05 (t, 1H); 6.09 (d, 2H). MS: m/z = 314 (M + ) and 316 (M + ). Hydrogenation of cardol Cardol (3.0 g) was dissolved in 10 mL of ethanol (previously purged with H 2 ), and 10% Pd/C (0.3 g) was added
tartrate were C 4 H 6 O 6 , CaCl 2 , CdCl 2 , and Na 2 SiO 3 ; all the chemicals were of AR grade. The crystallization apparatus consists of borosilicate glass test tubes of length 20 cm and diameter 2.5 cm placed vertically on wooden stands. Tartartic acid
