Preparation of ion-imprinted polyvinyl sulfonate-grafted silica particles for trace enrichment of Th(IV) prior to determination by inductively coupled plasma-mass spectrometry

Grafting from polymerisation technique has been used to prepare Th(IV) ion-imprinted polyvinyl sulfonate (IIPVS)-bonded silica particles. The graft polymerisation of vinyl sulfonate (VS) on the surface of silica particles was achieved in aqueous medium through thermal decomposition of surface-bound azo initiators (60°C) in the presence of thorium ion. The prepared material was characterised by Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The entrapped template ion was then removed using 2 M HCl. The experimental batch rebinding data were successfully described by the Langmuir–Freundlich model. The prepared material was then packed to a PTFE micro-column (20 mm × 3.0 mm, id) to evaluate its efficiency in column operations prior to determination by inductively coupled plasma-mass spectrometry (ICP-MS). The limit of detection of the method and breakthrough capacity of the column was evaluated as 0.074 µg L^?1 and 0.83 mg g^?1, respectively. The selectivity of the prepared polymer towards Th(IV) ion was investigated in the presence of some foreign competitor ions, including U(VI). Finally, the proposed method has been used to determine Th(IV) ion in real samples.     

The chemical behavior and degradation mitigation effect of cerium oxide nanoparticles in perfluorosulfonic acid polymer electrolyte membranes

Perfluorosulfonic acid membranes are susceptible to degradation during hydrogen fuel cell operation due to radical attack on the polymer chains. Mitigation of this attack by cerium-based radical scavengers is an approach that has shown promise. In this work, two formulations of crystalline cerium oxide nanoparticles, with an order of magnitude difference in particle size, are incorporated into said membranes and subjected to proton conductivity measurements and ex-situ durability tests. We found that ceria is reduced to Ce(III) ions in the acidic environment of a heated, humidified membrane which negatively impacts proton conductivity. In liquid and gas Fenton testing, fluoride emission is reduced by an order of magnitude, drastically increasing membrane longevity. Sideproduct analysis demonstrated that in the liquid Fenton test, the main point of attack is weak polymer end groups, while in the gas Fenton test, there is additional side-chain attack. Both mechanisms are mitigated by the addition of the ceria nanoparticles, whereby the extent of the concentration-dependent durability improvement is found to be independent of particle size.     

A new nano‐sized mononuclear Cu (II) complex with N,N‐donor Schiff base ligands: sonochemical synthesis,characterization, molecular modeling and biological activity

A new, simple Cu²⁺ nano‐structure Schiff base complex in methanol medium has been synthesized by the ultrasonic method. Structure of the compound was confirmed by FT‐IR, GC‐Mass and other spectroscopic techniques. The copper oxide (CuO) was achieved from the copper nano‐structure Schiff base complex as the raw material after calcination for 3 hr at 600 °C. According to results Cu²⁺ gives a complex with mole ratio 1:2 of metal to ligand (ML₂) with Schiff base which a distorted square planer is the most probable geometry for it. The calculations results from XRD patterns propose the nano‐sized complexes. The SEM images show morphology of both the copper complex and the CuO powder were plate‐like. The metal chelates of Cu²⁺ in two states of bulk and nano have been screened for their in vitro antibacterial activity against four bacteria, gram‐positive (Staphylococcus aureus) and gram‐negative (Escherichia coli) and three strains of fungus (Aspergillus flavus). The nano metal chelates were shown to possess more antibacterial activity than the bulk chelate. Finally, the empirical parameters of Schiff base compounds showed a good agreement with theoretical ones.     

Selective solid phase extraction of palladium by adsorption of its 5(p-dimethylaminobenzylidene)rhodanine complex on silica-PEG as a new adsorbent

The nickel(II) complex of a deoxyribonucleic acid (DNA-Ni²⁺) was directly electrodeposited on the surface of a glassy carbon electrode (GCE) to give a DNA-Ni/GCE electrode. It was investigated in terms of its capability of electro-oxidizing methanol in alkaline medium. It exhibits stable redox behavior of the Ni²⁺/Ni³⁺ couple by cyclic voltammetry. The DNA-Ni²⁺ membrane showed excellent electrocatalytic suitability for the electro-oxidation of methanol, is stable and responds reproducibly. The linear range for the detection of methanol in alkaline medium is from 8.0 µM to 2.4 mM, and the limit of detection is 2.0 µM (at a signal-to-noise ratio of 3).     

Unique substituted 3-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]benzimidazole-1-carboxamides generated by Ugi 3CC using bifunctional starting material

2-(2-Formyl-1H-benzimidazol-1-yl)acetic acid, as a bifunctional formyl-acid was prepared in four steps. This compound underwent one-pot reaction with primary amines, and alkyl isocyanides under Ugi conditions. A series of novel 3-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]benzimidazole-1-carboxamides were obtained in moderate to excellent yields.     

EIT based tunable metal composite spherical nanoparticles

Optical polarizability of a composite metal–dielectric and dielectric–metal spherical nanoparticle is investigated in view of achieving all-optical tunability. In this work, the Electromagnetically Induced Transparency (EIT) implemented in the shell or core of the nanoparticle is used. For the proposed nanoparticle, we show that EIT phenomenon can be utilized to tune the resonance frequency in the frequency response of polarizability. We present a quasi-static analysis for determining polarizability of the nanoparticle. According to our simulation results, all-optical tunability of polarizability can be achieved for reasonable values of optical pump power. Also, we demonstrate how the extinction quality factor and electric field distribution can be controlled for the introduced nanoparticle.     

The reaction of (N‐isocyanimino) triphenylphosphorane with an electron‐poor α‐haloketone in the presence of aromatic carboxylic acids: A novel three‐component reaction for the synthesis of disubstituted 1,3,4‐oxadiazole derivatives

Reactions of electron‐poor α‐haloketones with (N‐isocyanimino) triphenylphosphorane in the presence of aromatic carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford disubstituted 1,3,4‐oxadiazole derivatives in high yields. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:368–372, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20626     

Full-wave analysis of photonic-crystal structures with multi quantum well active region

In this paper, a semi-classical formulation for modeling photonic-crystal (PC) structures with a four-layer multi quantum well (MQW) active region is presented. The formulation treats the electromagnetic fields as a classical entity, while employing the quantum-mechanically derived rate equations to analyze the active medium. Using the Poynting theorem, we interrelate the two sets of equations, namely the MQW rate equations and Maxwell's equations. The formulation involves the stimulately emitted photon density in the former and a virtual volume current density representing the generated photons in the latter. With the help of this formulation, we then model a PC optical amplifier as well as a PC hexagonal-defect cavity laser and solve the obtained equations after replacing the involved spatial and temporal derivatives by pseudo-spectral and Runge-Kutta's formulations, respectively. The formulation also takes the effect related to gain saturation and frequency broadening into account.     

Green and efficient synthesis of 1H-indazolo[1,2-b] phthalazine-1,6,11(13H)-triones using ZrO(NO3)2.2H2O as a novel catalyst and theoretical study of synthesized compounds

The one-pot three-component synthesis for the preparation of 1H-indazolo[1,2-b] phthalazine-1,6,11(13H)-triones through condensation of phthalimide, hydrazine monohydrate, dimedone, and aromatic aldehydes in the presence of a novel catalytic amount of ZrO(NO₃)₂.2H₂O at reflux conditions in water has been reported. Quantum theoretical calculations for the three structures of compounds ( 5a , 5b , and 5c ) were performed using the G3MP2, LC-ωPBE, MP2, and B3LYP methods with the 6-311 + G** basis set. After optimizing the structures, geometric parameters were obtained and experimental measurements were compared with the calculated data. The structures of the products were confirmed by IR, ¹H NMR, ¹³C NMR, and elemental analysis. IR spectra data and ¹H NMR and ¹³C NMR chemical shifts computations of the 1H-indazolo[1,2-b]phthalazine-1,6,11(13H)-trione derivatives in the ground state were calculated. Frontier molecular orbitals, total density of states, thermodynamic parameters, and molecular electrostatic potentials of the title compounds were investigated by theoretical calculations. Molecular properties such as the ionization potential (I), electron affinity (A), chemical hardness (η), electronic chemical potential (μ), and electrophilicity (ω) were investigated for the structures. Consequently, there was an excellent agreement between experimental and theoretical results.     

Facile,efficient and diastereoselective synthesis of α-hydrazine tetrazoles through a novel one-pot four-component reaction

A novel and efficient method for the diastereoselective synthesis of α-hydrazine tetrazoles via an isocyanide-based multicomponent reaction is reported in good yields. The α-hydrazine tetrazoles were obtained by a facile azide Ugi four-component reaction (U-4CR) using cyclic ketones, trimethylsilyl azide, hydrazides, and corresponding isocyanide without any catalyst and with high bond forming efficiency at room temperature.