Catalytic activity of manganese(III)-oxazoline complexes in urea hydrogen peroxide epoxidation of olefins: The effect of axial ligands

The catalytic activity of two manganese(III)-oxazoline complexes [Mn(phox)₂(CH₃OH)₂]ClO₄ and Mn(phox)₃ (Hphox = 2-(2′-hydroxylphenyl)oxazoline), was studied in the epoxidation of various olefins. All of epoxidation reactions were carried out in (1:1) mixture of methanol:dichloromethane at room temperature using urea hydrogen peroxide (UHP) as oxidant and imidazole as co-catalyst. The epoxide yields clearly demonstrate the influence of steric and electronic properties of olefins, the catalysts and nitrogenous bases as axial ligand. [Mn(phox)₂(CH₃OH)₂]ClO₄ catalyst with low steric properties has higher catalytic activity than Mn(phox)₃. The highest epoxide yield (95%) was achieved for indene at the presence of [Mn(phox)₂(CH₃OH)₂]ClO₄ within 5 min. The proximal and distal interactions of strong π-donor axial ligands such as imidazole with the active intermediate are efficiently increased activity of the catalytic system.     

New PVC-membrane electrode based on charge-transfer inclusion complex between I2 and 1,4,8,11-tetraazacyclotetracdecane for selective determination of I3 − ions

A new triiodide ion-selective electrode based on charge-transfer complex of iodine with 1,4,8,11-tetraazacyclotetracdecane as membrane carrier was prepared. The best performance of electrode observed with the membrane having the ligand–PVC–NPOE–NaTPB composition 3.0:33:66:0.5 mg which worked well over a wide concentration range 2.8 × 10^?6–1.4 × 10^?1 M with a Nernstian slope of 59.6 ± 0.3 mV per decade and a detection limit of 1.2 × 10^?6 M. This electrode showed a response time of 25 s and was used over a period of 2 months. The electrode exhibits an anti-Hofmeister selectivity sequence with a performance for triiodide at pH 1.5–10.2. The response mechanism of the electrode was investigated by UV–Vis spectroscopic technique. The electrode was successfully applied as an indicator electrode in the potentiometric titration of ascorbic acid and hydroquinone in drugs.     

Adsorptive cathodic stripping voltammetry determination of ultra trace levels of cobalt

The complexation of Co(II) with 4-(2-pyridylazo)resorcinol (PAR) was studied by spectroscopy and voltammetry. In addition, an adsorptive stripping voltammetric method was developed for the determination of ultra trace levels of Co(II) using a hanging mercury drop electrode. The method is based on accumulation of Co(II) on a mercury electrode using PAR as the complexing agent. The effects of instrumental and chemical parameters on the sensitivity of the method were investigated. The detection limit of the method is 0.003 ng/mL. Most foreign species do not interfere with the determination. The high sensitivity and selectivity of this method were demonstrated by determination of cobalt in blood and water samples.     

An Anonymous Surveying Protocol via Greenberger-Horne-Zeilinger States

A new experimentally feasible anonymous survey protocol with authentication using Greenberger-Horne-Zeilinger (GHZ) entangled states is proposed. In this protocol, a chief executive officer (CEO) of a firm or company is trying to find out the effect of a possible action. In order to prepare a fair voting, the CEO would like to make an anonymous survey and is also interested in the total action for the whole company and he doesn’t want to have a partial estimate for each department. In our proposal, there are two voters, Alice and Bob, voting on a question with a response of either ”yes” or ”no” and a tallyman, whose responsibility is to determine whether they have cast the same vote or not. In the proposed protocol the total response of the voters is calculated without revealing the actual votes of the voters.     

Synthesis and Catalytic Applications of Sulfonic Acid Group–Functionalized Nano- and Microsilica Structures

Sulfonic acid group–functionalized nano- and microsilica with different sizes and shapes were synthesized. Silica nanospheres with an average size of 225 nm, silica microtubes, and fine silica gel were prepared and functionalized by sulfonic acid. Their catalytic activity was investigated in the three-component Biginelli reaction for the synthesis of dihydropyrimidinones.     

Friedel-Crafts Acylation of Aryl-Substituted Carboxylic Acids Catalyzed by Zeolite

A convenient heterogeneous catalytic intramolecular Friedel-Craftsacylation of some aryl-substituted carboxylic acids overY-faujasite-type zeolite is described. It is an effective method forthe synthesis of 4,9-diketo-1,2,3,4-tetrahydroacenaphthenes.     

Radar Absorption Properties of Ni0.5Zn0.5Fe2O4/PANI/epoxy Nanocomposites

A nitrate? citrate gel was prepared from metallic nitrates and citric acid by sol? gel process and was further used to synthesize Ni_0.5Zn_0.5Fe₂O₄ nanocrystalline powder by auto‐combustion. Then, two novel 15 and 35% (w/w) magnetic Ni_0.5Zn_0.5Fe₂O₄ containing polyaniline nanocomposites, named as PANI‐Ni15 and PANI‐Ni35, respectively, were prepared via in‐situ polymerization of aniline in an aqueous solution containing proper amount of Ni_0.5Zn_0.5Fe₂O₄ magnetic powder. The incorporation of the nanopowders to PANI matrix was confirmed by X‐ray diffraction (XRD), IR and SEM. Synthesized PANI‐NiZn ferrite composite particles were subsequently added to an epoxy resin matrix to produce related nanocomposites. The morphological properties of these nanocomposite materials were investigated by SEM and TEM. The electromagnetic‐absorbing properties were studied by measuring the reflection loss in the frequency range of 8.0 to 12.0 GHz. Results showed the reflection loss of the PANI‐Ni35 composite is higher than pure polyaniline and PANI‐Ni15. The good reflection loss of the nanocomposites suggests their potential applicability as radar absorber.