Synthesis,Structural Characterization,and Cation Transport of Tripotassium Pentabismuth Arsenate K3Bi5(AsO4)6

During the exploration of the K₂O-Bi₂O ₃ -As₂O₅ system, single crystals of a new arsenate of trivalent bismuth, K₃Bi₅(AsO₄) ₆, were isolated by solid state reaction at 600°C. The title compound crystallizes in the monoclinic system, space group C2/c (N°15) with a = 18.257(2) Å, b = 7.260(1) Å, c = 20.130(4) Å, β = 119.86(1)°, and Z = 4. Its structure consists of a three-dimensional framework made up of AsO₄ tetrahedra and BiO₆ and BiO₇ polyhedra sharing edges and corners, delimiting cavities wherein K⁺ ions reside. This compound exhibits a potassium ion conductivity but with rather low conductivity value.     

Synthesis of New Benzylic Di-, Tri-, and Tetraphosphonic Acids as Potential Chelating Agents

Abstract

New di-, tri-, and tetraphosphonic acids were synthesized starting from four o-hydroxymethyl phenol derivatives and obtained in three steps in good overall yield. The phosphonic acids were isolated and purified using semi-preparative C₁₈ HPLC column. The new compounds were characterized using different spectroscopic methods (¹H, ¹³C, and ³¹P NMR; ESI MS; and MSⁿ, IR).

GRAPHICAL ABSTRACT     

β‐LiMoO2(AsO4)

A new non‐centrosymmetrical form of lithium molybdyl arsenate has been synthesized and grown as a single crystal. The structure of β‐LiMoO₂(AsO₄) is built up of corner‐sharing AsO₄ tetrahedra and MoO₆ octahedra which form a three‐dimensional framework containing tunnels running along the a axis, wherein the Li⁺ cations are located. This novel structure is compared with the compound LiMoO₂(AsO₄) of the same formula, and with those of AMO₂(XO₄) (A is Na, K, Rb or Pb, M is Mo or V, and X is P or As) and B(MoO₂)₂(XO₄)₂ (B is Ba, Pb or Sr).     

The role of tin(II) octoate – azobisisobutyronitrile complex in the formation rate of the respective networks in simultaneous interpenetrating polymer networks

Simultaneous interpenetrating polymer networks (IPNs) based on polyether polyurethane (PUR) and poly(methyl methacrylate‐co‐trimethylol‐propane trimethacrylate) (PMMA) were prepared in bulk at 60°C, using tin(II) octoate and azobisisobutyronitrile (AIBN) as pur polymerization catalyst and free‐radical initiator, respectively. The kinetics of the PUR network formation, PMMA network formation as well as PUR/PMMA IPN formation were studied independently by Fourier transform infra‐red spectroscopy. The simultaneous formation of the two networks interfered with each other, although they follow different polymerization mechanisms. Mainly two effects concerning the free‐radical polymerization have been seen: a decrease of the initiation period and an earlier appearance of the Trommsdorff effect when increasing the concentration of the catalyst. On the other hand, the presence of AIBN in the reaction medium drastically reduced the catalytic efficiency of the organotin compound. An explanation of these results for this particular activating system could be the formation of a cyclic equimolar complex by coordination of the nitrile groups of AIBN with the Sn(II) atom. Complexation both reduces the effective catalyst concentration and induces steric constraints in the azo bond of AIBN, rendering this linkage weaker and more easily cleavable and allowing an early decomposition into radicals of the complexed AIBN. The maximum rate corresponds to a 1:1 complex. Further, decomposition into radicals leads to tin oxidation and formation of a new tetravalent organotin compound, the catalytic activity of which is lower than that of pure tin(II) octoate for the isocyanate‐alcohol reaction.     

Electrochemical determination of sulfaguanidine using COOH-MWCNT coated GC electrode

The electrochemical behavior of sulfaguanidine was investigated in PBS buffer aqueous solutions. Cyclic voltammograms have shown that (1) the Sg provided a well-defined irreversible oxidation peak (2) the signal-to-background current ratio is 3 times higher at COOH-MWCNT coated GCE than that of bare GCE and (3) the modifying GCE surface by COOH-MWCNT led to a significant improvement (2.7 folds) of the electrochemical response. It has been shown that Sg oxidizes according to a diffusion-controlled mechanism. A linear calibration curve was obtained for the oxidation of Sg at 10–70 μM. The COOH-MWCNT coated GCE has also been successfully used for the determination of Sg in real samples.