Preparation and Crystal Structure of Lead (II) Complex with Propane-1,2-Diamine

Abstract  

The reaction of propane-1,2-diamine (pdam) with lead (II) nitrate in the ethanol solution led to the formation of a lead (II) complex, [Pb(NO₃)(pdam)₂]NO₃ (1), with interesting coordination environment of the lead (II) ion. The compound was characterized by elemental analysis and IR spectroscopy and its crystal structure was determined by single crystal X-ray structural analysis. Lead (II) ion is coordinated by two neutral N,N′-bidentate propane-1,2-diamine ligands and by an O,O′-bidentate nitrate ion in a complex cation of 1. There is also an uncoordinated nitrate ion as counter-ion. The primary coordination sphere around lead (II) ion includes four N atoms (Pb–N, 2.377(4)–2.644(4) ?). The effective coordination around lead (II) ion could be described as a highly distorted octahedron if the Pb···O contacts (Pb1···O4, 3.090(4) ?, Pb1···O5, 3.177(3) ?) are included. The coordination polyhedron is better described as a distorted pentagonal pyramid due to the presence of stereochemically active lead (II) ion lone pair of electrons in the axial position of the pyramid. Thus, the complex is hemidirected. Complex cations and nitrate counter-ions are connected into 3D structure by hydrogen bonds of the N–H···O type.     

M(II) Schiff base complexes (M = zinc,manganese, cadmium,cobalt, copper,nickel, iron,and palladium) supported on superparamagnetic Fe3O4@SiO2 nanoparticles: synthesis,characterization and catalytic activity for Sonogashira–Hagihara coupling reactions

A series of magnetically separable catalysts consisting of Schiff base complexes of metal ions (Zn, Mn, Cd, Co, Cu, Ni, Fe and Pd) supported on superparamagnetic Fe₃O₄@SiO₂ nanoparticles has been prepared. The structural features of the catalysts were characterized by XRD, FTIR, TEM, FE-SEM, DLS, VSM, UV–Vis, TGA, AFM and N₂ adsorption–desorption. Some of the Fe₃O₄@SiO₂/Schiff base complexes were found to be efficient catalysts for the Cu-free and the phosphine free Sonogashira–Hagihara coupling reaction of aryl halides and phenylacetylene. The catalysts are superparamagnetic, and thus could be easily separated by the utilization of an external magnetic field, and could be reused for six cycles without significant loss of activity.     

Uranium extraction from aqueous solution using dried and pyrolyzed tea and coffee wastes

The adsorption of U(VI) onto dried and pyrolyzed tea and coffee wastes was investigated. The adsorption properties of the materials were characterized by measuring uranium uptake as a function of solution pH, kinetics and adsorption isotherms. pH profile of uranium adsorption where UO₂ ²⁺ is expected to be the predominant species was measured between pH 0 and 4. Both Langmuir and Freundlich adsorption models were used to describe adsorption equilibria, and corresponding constants evaluated. Using the Langmuir model, the maximum adsorption capacity of uranium by dried tea and coffee wastes was 59.5 and 34.8 mg/g, respectively at 291 K. Adsorption thermodynamic constants, ΔH° ΔS° and ΔG° were also calculated from adsorption data obtained at three different temperatures. Adsorption thermodynamics of uranyl ions on dried tea and coffee systems indicated spontaneous and endothermic processes. Additionally, a Lagergren pseudo-second-order kinetic model was used to fit the kinetic experimental data for both adsorbents and the constants evaluated. Dried tea and coffee wastes proved to be effective adsorbents with high capacities and significant advantage of a very low cost.     

Control of selectivity in the generation and reactions of oxonium ylides

Dirhodium catalyzed reactions of aryl-substituted tetrahydropyranone diazoacetoacetates produce ylide intermediates that unexpectedly yield two oxabicyclo[4.2.1]-nonane diastereoisomers, but a single diastereoisomer is formed by increasing the steric bulk of the aryl substituent.     

Selective and sensitive optical chemosensor for detection of Ag(I) ions based on 2(4-hydroxy pent-3-en-2-ylideneamine) phenol in aqueous samples

A selective and sensitive chemosensor, based on the 2(4-hydroxy pent-3-en-2-ylideneamine) phenol (HPYAP) as chromophore, has been developed for colorimetric and visual detection of Ag(I) ions. HPYAP shows a considerable chromogenic behavior toward Ag(I) ions by changing the color of the solution from pale-yellow to very chromatic-yellow, which can be easily detected with the naked-eye. The chemosensor exhibited selective absorbance enhancement to Ag(I) ions in water samples over other metal ions at 438 nm, with a linear range of 0.4–500 μM (r² = 0.999) and a limit of detection 0.07 μM of Ag(I) ions with UV–vis spectrophotometer detection. The relative standard deviation (RSD) for 100 μM Ag(I) ions was 2.05% (n = 7). The proposed method was applied for the determination Ag(I) ions in water and waste water samples.     

Two-dimensional elastic phase-field simulation of fcc to bcc martensitic phase transformations in polycrystals

Numerical results of two-dimensional elastic phase-field simulations of martensitic phase transformations (fcc-bcc) in polycystals are presented. The stresses and strains in the diffuse interface domain are described by following Khachaturyan's approach of microelasticity. A fixed-point iteration algorithm in Fourier space is used to solve the mechanical equilibrium condition for the microscopic, inhomogeneous strain field and apply mechanical loadings to the system. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal Growth of Diazabicyclo[2.2.2]octane-1,4-diium dichromate

Abstract  

The crystal growth of (C₆H₁₄N₂)[Cr₂O₇], consists of a diazabicyclo[2.2.2]octane-1,4-diium cation and a discrete dichromate anion, in solution has been determined under the influence of various factors. Four factors, which influence the crystal size, crystal growth and nucleation, were chosen. These factors are concentration, temperature, type of solvent and method of crystallization. Taguchi design of experiments (DOE) method has been used for to plan a minimum number of experiments and optimization of crystallization processes. Crystallization of diazabicyclo[2.2.2]octane-1,4-diium dichromate with desirable particle size, shape and minimum time of crystal growth as performance characteristics were studied. The changes in the crystal growth habit were observed and could be explained by the differences in the morphology on the various photograph of this compound.     

Stochastic invariance of closed sets with non-Lipschitz coefficients

This paper provides a new characterization of the stochastic invariance of a closed subset of ${\mathbb{R}}^d$ with respect to a diffusion. We extend the well-known inward pointing Stratonovich drift condition to the case where the diffusion matrix can fail to be differentiable: we only assume that the covariance matrix is. In particular, our result can be applied to construct affine and polynomial diffusions on any arbitrary closed set.