Reaction of carbon disulfide with 2-bromoimidazolium salts. Novel bicyclic mesoionic thiazolo[3,2-a]imidazoles

A new class of thiazolo[3,2-a]imidazole derivatives is obtained in good yields, by reacting 1-methyl-2-bromoimidazolium salts bearing N⁺-CH₂COAr, N⁺-CH₂COMe, N⁺-CH₂COOMe, or N⁺-CH₂CN fragments, with carbon disulfide in the presence of Et₃N at room temperature. The mesoionic structures of these compounds are established by NMR spectroscopy and by single-crystal X-ray analysis.     

A selective modified nanoporous silica as sorbent for separation and preconcentration of dysprosium in water samples prior to ICP-OES determination

In this research a new physically functionalized nanoporous silica (SBA-15) using N′-[(2-hydroxy phenyl) methylene] benzohydrazide (BBH) was utilized as a selective sorbent for the separation, preconcentration and determination of dysprosium (Dy) in natural water by inductively coupled plasma optical emission spectrometry (ICP-OES). The selectivity of BBH to Dy (III) ion was previously tested by conductometric and spectroscopic methods. Conditions for effective adsorption of Dy were optimized with respect to experimental parameters in batch process. The extraction recovery was 96.5, analytical curve was linear in the range 0.2–1000?µgL^?1, and the detection limit was 0.05?ng?mL^?1. The relative standard deviation (RSD) under optimal conditions was 3.2% (n?=?10). The sorbent exhibited high adsorption capacity and fast rate of equilibrium for sorption of Dy ions. The method was applied for recovery and determination of dysprosium in different environmental water samples.     

Etude theorique de la cycloaddition dipolaire 1–3

A theoretical study of the 1,3-dipolar cycloaddition reaction of: diazomethane with ethylene has been carried out by the LCAO-SCF-MO method. The potential energy hypersurface for the reaction and the electronic structure of the transition state have been investigated.     

Multifaceted palladium catalysts towards the tandem diboration-arylation reactions of alkenes

Novel Pd(2) (6+) compounds have been synthesized in high yield. These compounds and their Pd(2) (4+) counterparts as synthetic precursors mediate the diboration of vinylarenes and aliphatic 1-alkenes, and under mild and basic reaction conditions they produce a variety of 1,2-diboronate esters with excellent conversions and chemoselectivities. The presence of bis(catecholato)diboron (B(2)cat(2)) favours the reduction of Pd(III) to Pd(II), while the catalytic precursor of Pd(II) is transformed into Pd(0)-nanoparticles. An "in situ" catalytic tandem reaction has been designed to transform the diboronate intermediates into the monoarylated product, which after oxidative workup, provides the carbohydroxylated adduct. Eventually, the same catalyst performs both sequences with total conversion from the alkene.     

Chaos control and synchronization of fractional order delay‐varying computer virus propagation model

In the present article, the authors have studied the dynamical behavior of delay‐varying computer virus propagation (CVP) model with fractional order derivative, and it is found that the chaotic attractor exists in the considered fractional order system. In order to eliminate the chaotic behavior of fractional order delay‐varying CVP model, feedback controlmethod is used. This article also dealswith the synchronization between controlled and chaotic delay‐varying CVPmodel via active controlmethod. The fractional derivative is described in the Caputo sense. Numerical simulation results are carried out by means of Adams‐Boshforth‐Moultonmethod with the help ofMATLAB, and the results are successfully depicted through graphs .Copyright © 2015 John Wiley & Sons, Ltd.     

Imidazolium Based Probes for Recognition of Biologically and Medically Relevant Anions

The imidazolium derivatives due to their positive charge possess one of the most polarized and positively charged proton at C2‐H to form strong ionic hydrogen bond (also termed as double ionic hydrogen bond) with anions and also provide opportunities for anion – π interactions with electron‐deficient imidazolium ring. In the present review article, imidazolium based molecular probes for their ability to recognize inorganic anions like halides, cyanide, perchlorate, carboxylic acids, phosphate, sulfate etc. and their derived molecules viz. nucleotides, DNA, RNA, surfactants, proteins, etc have been discussed. The review covers the literature published after year 2009 and has > 130 references. The previous literature has already been discussed by Yoon et al. in two review articles published in Chem. Soc. Rev. 2006 and 2010.     

Enhanced photocatalytic activity of graphene–TiO2 composite under visible light irradiation

Novel graphene–TiO₂ (GR–TiO₂) composite photocatalysts were synthesized by hydrothermal method. During the hydrothermal process, both the reduction of graphene oxide and loading of TiO₂ nanoparticles on graphene were achieved. The structure, surface morphology, chemical composition and optical properties of composites were studied using XRD, TEM, XPS, DRS and PL spectroscopy. The absorption edge of TiO₂ shifted to visible-light region with increasing amount of graphene in the composite samples. The photocatalytic degradation of methyl orange (MO) was carried out using graphene–TiO₂ composite catalysts in order to study the photocatalytic efficiency. The results showed that GR–TiO₂ composites can efficiently photodegrade MO, showing an enhanced photocatalytic activity over pure TiO₂ under visible-light irradiation. The enhanced photocatalytic activity of the composite catalysts might be attributed to great adsorptivity of dyes, extended light absorption range and efficient charge separation due to giant π-conjugation system and two-dimensional planar structure of graphene.     

The stochastic EOQ model with random sales price

The article deals with a stochastic economic order quantity (EOQ) model over a finite time horizon where uniform demand over the replenishment period is price dependent. The selling price is assumed to be a random variable that follows a probability density function. As demand is probabilistic, stock out situation may occur. Based on the partial backlogging and lost sale cases during stock out period, the author develops the criterion for the optimal solution for the replenishment size such that the integrated expected profit is maximized. Moreover, the article suggests a new function regarding price dependent demand. Finally, numerical examples and its sensitivity analysis of key parameters are given to illustrate the proposed model.     

Synthesis and characterization of high-dimensional structure based on paradodecatungstate clusters and sodium–aminoacetic acid complex subunits

An organic–inorganic hybrid material based on paradodecatungstate building blocks and sodium–aminoacetic acid complex subunits,{Na₁₀(H₃N–CH₂–COO)₂[H₂W₁₂O₄₂]}·28H₂O (1), have been synthesized under mildly acidic conditions. This compound was characterized by single-crystal X-ray diffraction, elemental analysis, IR and UV–visible spectroscopies, and cyclic voltammetry. The compound crystallizes in the triclinic space group P-1 with a = 11.879(2) Å, b = 12.706(2) Å, c = 13.067(2) Å, α = 74.11(3)°, β = 79.71(3)°, γ = 65.95(3)°, V = 1727.2(5) Å³, and Z = 1. The crystal structure consists of infinite 2D layers constructed from [H₂W₁₂O₄₂]^10? clusters and sodium–aminoacetic acid complexes; adjacent layers are further joined by the complex units and sodium cations to yield a three-dimensional network.