Spectral properties of some metal complexes derived from uracil-thiouracil and citrazinic acid compounds

The reaction of FeCl(3) with uracil (H(2)L(1)), citrazinic acid (H(2)L(6)), 5-(phenylazo)citrazinic acid (H(2)L(7)), 5-(m-hydroxyphenylazo)citrazinic acid (H(2)L(8)) and 5-(m-nitrophenylazo)citrazinic acid (H(2)L(9)) leads to the formation of complexes with the empirical formula Fe(HL)(3).nH(2)O (n=1-3). All of the prepared complexes have octahedral complexation geometry where the azo group is not the reactive site for complexation. Thiouracil (H(2)L(2)) and the 5-(substituted phenylazo)thiouracil (H(2)L(3)-H(2)L(5)) ligands are bidentates on complexation with Co(II), Ni(II) and Cu(II). The complexes have been characterized by elemental analyses, IR, electronic spectra, magnetic susceptibility, DTA, electron spin resonance (copper complexes) and M?ssbauer spectra (iron complexes). The coordination bond lengths between the metal ion and the active centers for complexation were calculated.     

A note on linear θ-derivations on JB1-triples

In this paper we prove a generalization of the stability of the functional equation in the spirit of Hyers, Ulam and Rassias. Also we introduce the concept of linear θ-derivations on JB¹-triple, and prove the generalization of the stability of the functional equation in the spirit of Hyers, Ulam and Rassias of linear θ-derivations on JB¹-triple. For resent results see [1], [2], [3].     

Extraction of propylbenzene or butylbenzene from dodecane using 4-methyl-N-butylpyridinium tetrafluoroborate, [mebupy][BF4], as an ionic liquid at different temperatures

Equilibrium tie line data have been determined for the two ternary liquid systems, namely {dodecane + propylbenzene + [mebupy][BF₄]} and {dodecane + butylbenzene + [mebupy][BF₄]} at temperatures (313, 323, and 333) K and atmospheric pressure. The effects of temperature and solvent to feed ratio upon solubility, selectivity, and distribution coefficient were investigated experimentally. The reliability of the experimental data was tested using the Othmer–Tobias correlation. The experimental results were regressed to estimate the interaction parameters between each of the three pairs of components for the UNIQUAC and the NRTL models as a function of temperature. In addition, the LLE data were also correlated with the UNIQUAC and NRTL models in a satisfactory manner.     

Synthesis,Crystal Structure,and Characterization of A New Hydrogen Phosphate Templated By 3-Aminophenyl Sulfone

Abstract

The synthesis and crystal structure of a new noncentosymmetric compound with the general formula: [C₄₈H₅₁N₈O₈S₄](HPO₄)H₂PO₄ are reported. The structure, determined by single-crystal X-ray diffraction at 150 K can be described as organic layers [C₄₈H₅₁N₈O₈S₄]³⁺ parallel to the (a and c) plane between which the inorganic groups consisting of H₂PO₄ ^? and HPO₄ ^2? entities are inserted as inorganic layers. In this atomic arrangement, H-bonds and Vander-Waals interactions between the different species play an important role in the tridimensional network cohesion. Solid-state ¹³C and ³¹P MAS NMR spectroscopies are in agreement with the X-ray structure.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Direct Electrochemistry of Cholesterol Oxidase Immobilized on a Conducting Polymer: Application for a Cholesterol Biosensor

Direct electrochemistry of cholesterol oxidase (ChOx) immobilized on the conductive poly‐3′,4′‐diamine‐2,2′,5′,2″‐terthiophene (PDATT) was achieved and used to create a cholesterol biosensor. A well‐defined redox peak was observed, corresponding to the direct electron transfer of the FAD/FADH₂ of ChOx, and the rate constant (k_s) was determined to be 0.75 s^?1. Glutathione (GSH) covalently bonded with PDATT was used as a matrix for conjugating AuNPs, ChOx, and MP, simultaneously. MP co‐immobilized with ChOx on the AuNPs‐GSH/PDATT exhibited an excellent amperometric response to cholesterol. The dynamic range was from 10 to 130 μM with a detection limit of 0.3±0.04 μM.     

Structure,chemical bonding,and 45Sc solid state NMR of Sc2RuSi2

The silicide Sc₂RuSi₂ was synthesized from the elements by arc-melting. The structure was refined on the basis of single crystal X-ray diffractometer data: Zr₂CoSi₂ type, C2/m, a = 1004.7 (2), b = 406.8 (1), c = 946.6 (2) pm, β = 117.95 (2), wR2 = 0.0230, 743 F² values, and 32 variables. The structure consists of a rigid three-dimensional [RuSi₂] network in which the two crystallographically independent scandium atoms fill larger cages of coordination numbers 16 and 15, respectively. The [RuSi₂] network shows short Ru–Si distances (234–247 pm) and two different Si₂ pairs: Si1–Si1 at 247 and Si2–Si2 at 243 pm. Each silicon atom has trigonal prismatic Sc₆ (for Si2) or Sc₄Ru₂ (for Si1) coordination. These building units are condensed via common edges and faces. The various Sc–Sc distances between the prisms range from 327 to 361 pm. From electronic structure investigation within DFT, chemical bonding shows a major role of Ru–Si bonding and the presence of strong electron localization around Si–Si pairs pointing to a polyanionic silicide network [RuSi₂]^δ?. The ⁴⁵Sc MAS-NMR spectra recorded at 11.7 and 9.4 T clearly resolve the two distinct scandium sites. The large electric field gradients present at both scandium sites result in typical line shapes arising from second-order quadrupole perturbation effects.     

Synthesis of highly ordered cubic zeolite A and its ion-exchange behavior

Well-ordered cubic zeolites 4A were synthesised using sol–gel process in the presence of different silica and aluminum sources. The aluminum and silica sources determined whether or not zeolites were formed at precise silica/alumina mole ratio. Zeolites were formed only when the aluminum source was sodium aluminate, the silica source was fumed silica, colloidal silica or sodium metasilicate. Our findings indicated that the type of zeolite invariably obtained was 4A and SEM images indicated that the produced zeolites are cubic shaped crystals with planar surfaces and well-defined edges and sharp crystals. In turn, synthesis parameters are seen to have a significant effect in maximizing heavy metals uptake (for example Cu²⁺, Cr³⁺, Cd²⁺ and Ni²⁺) by synthesized zeolites. Zeolite 4A gave better heavy metal uptakes than amorphous or non-zeolite crystalline materials. This was attributed to higher ion-exchange capacity and higher BET specific surface area 445 m²/g and pore volume 0.141 cm³/g. The latter attribute possibly translates to greater accessibility of ion-exchange sites and selectivity towards metal type by this zeolite followed the sequence: Cu²⁺ > Cr³⁺ ≥ Cd²⁺ > Ni²⁺.     

Preparation and electrochemical properties of Co3O4-coated layered manganese oxide by a novel coating method

Potassium type birnessite (K-bir) was synthesized by O₂ oxidizing Mn²⁺ in aqueous solution of KOH. Co₃O₄-coated K-bir (Co-K-bir) was prepared by employing a novel coating method, in which the remaining OH⁻ ions on the particle surface of the as-precipitated K-bir reacted with Co²⁺ ions in aqueous solution, forming CoOOH coverage; the coating layer of CoOOH was subsequently annealed at 300 °C to transform into Co₃O₄. All the K-bir and Co-K-birs were investigated by scanning electron microscopy, transmission electron microscopy, inductive coupled plasma–atomic emission spectroscopy, Brunauer–Emmett–Teller specific area, and laser particle size analyzing techniques. Their electrochemical properties were also studied by discharging–charging at constant current. The results show that the covering layers of Co₃O₄ are incompact, and their average thickness are about 0.65–0.78 μm. Compared to the as-prepared and the annealed K-bir, the Co₃O₄-coated samples have higher initial discharge capacities and show distinctly improved cycleability performance.