Investigation of the anchoring silane coupling reagent effect in porphyrin sensitized mesoporous V-TiO2 on the photodegradation efficiency of methyl orange under visible light irradiation

In order to efficient utilization of visible light in the photodegradation reaction, mesoporous vanadium doped TiO₂ (V-TiO₂) particles sensitized by tetrakis(4-carboxyphenyl)porphyrin (TCPP) dyes were synthesized, and characterized. For investigation of the anchoring coupling between porphyrin and TiO₂ surface, two photocatalyst containing ester-like linkage (TCPP–V-TiO₂) and amide-like linkage (TCPP–NH₂–V-TiO₂) were compared in the photodegradation of methyl orange (MO) aqueous solution. It was found that the photocatalytic activity of the TCPP–V-TiO₂ was higher than TCPP–NH₂–V-TiO₂ (95 % compared to 62 %). Importantly, TCPP–V-TiO₂ was particularly stable in the visible light photocatalytic activity after six cycles.     

An Environmental Friendly Approach for the Synthesis of Spiro[indoline‐3′,2‐quinazoline]2′,4(3H)‐dione Using 1‐Methylimidazolium Hydrogen Sulfate,as Reusable Catalyst

A facile and environmentally benign procedure for the synthesis of 3‐aryl‐1H‐spiro[indoline‐3′,2‐quin‐azoline]2′,4(3H)‐dione from isatoic anhydride, aromatic amines and isatin derivatives in Brønsted acidic ionic liquid, 1‐methylimidazolium hydrogen sulfate, was reported. The ability to reuse the ionic liquid, the high yield, short reaction time and ease of purification are the important features of this process.     

Transport of charged Aerosol OT inverse micelles in nonpolar liquids

Surfactants such as Aerosol OT (AOT) are commonly used to stabilize and electrically charge nonpolar colloids in devices such as electronic ink displays. The electrical behavior of such devices is strongly influenced by the presence of charged inverse micelles, formed by excess surfactant that does not cover the particles. The presence of charged inverse micelles results in increased conductivity of the solution, affecting both the energy consumption of the device and its switching characteristics. In this work, we use transient current measurements to investigate the electrical properties of suspensions of the surfactant Aerosol OT in dodecane. No particles are added, to isolate the effect of excess surfactant. The measured currents upon application of a voltage step are found to be exponentially decaying, and can be described by an analytical model based on an equivalent electric circuit. This behavior is physically interpreted, first by the high generation rate of charged inverse micelles giving the suspension resistor like properties, and second by the buildup of layers of charged inverse micelles at both electrodes, acting as capacitors. The model explains the measurements over a large range of surfactant concentrations, applied voltages, and device thicknesses.     

Synthesis and Evaluation of a Molecularly Imprinted Polymer for Pre-concentration of Patulin from Apple Juice

Patulin, (4-hydroxy-4H-furo[3,2-c] pyran-2(6H)-one) is a toxic secondary metabolite produced by a wide range of fungal species growing on some fruits, including apples. A novel molecularly imprinted polymer (MIP) for patulin has been synthesized using oxindole as a dummy template. The synthesis of MIPs based on dummy templates is a solution to overcome “template bleeding” shortcoming in trace analysis. The polymer was prepared in a non-covalent approach with methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linker via free radical polymerization. It was revealed that the MIP particles in extraction columns displayed high affinity towards patulin and, therefore, subsequently employed for molecularly imprinted-solid phase extraction (MIP-SPE) of patulin from contaminated apple juice samples. The analysis of spiked samples showed good recoveries (>80%). Reproducibility, repeatability, and limit of detection of the proposed method were also investigated.     

Computational studies of effects of tubular lengths on the NMR properties of pristine and carbon decorated boron phosphide nanotubes

Density functional theory (DFT) calculations were performed to investigate the effects of tubular lengths on the nuclear magnetic resonance (NMR) properties of boron phosphide (BP) nanotubes. To this aim, the properties of pristine and carbon decorated (C-decorated) models of representative zigzag and armchair BP nanotubes were investigated. The results indicated that the atoms at the edges of nanotubes do not detect any significant changes. The NMR properties of boron atoms only detect slight changes but those of phosphorous atoms are more notable.     

Amplified oxadiazole derivative nano MgO–multiwall carbon nanotubes modified carbon paste electrode for the determination of dopamine in presence of morphine

In this paper, we report the fabrication of an amplified sensor to determine dopamine in the presence of morphine based on nano-MgO, multiwall carbon nanotubes, and an oxadiazole derivative. The electrochemical behavior and electrocatalyic activity of the sensor toward the oxidation of dopamine were investigated. Cyclic voltammetry was used to study the redox features of the sensor, and the results have shown that dopamine overpotential oxidation at the surface of the sensor was reduced to nearly 460 mV. The diffusion coefficient was estimated by chronoamperometry. Three segmented linear dynamic ranges over the range 0.05–5175.0 and detection limit of 0.021 μM for the quantification of dopamine were obtained using differential pulse voltammetry (DPV). The modified nanocomposite carbon paste electrode, which showed excellent sensitivity, selectivity, repeatability, and reproducibility, was satisfactorily employed to determine dopamine and morphine in actual samples.     

Synthesis and Dynamic NMR Study of a Functionalized Sulfonamide Phosphonate Diester

Abstract

Protonation of the highly reactive 1:1 intermediate produced in the reaction between triphenylphosphite and activated acetylene by sulfonamide leads to a phosphonate ylide, which undergoes methanol elimination in the presence of moisture to produce a highly functionalized sulfonamide phosphonate diester. A dynamic nuclear magnetic resonance (NMR) effect is observed in the ¹H NMR spectra of this compound as a result of restricted rotation around the single C?N bond. The coalescence temperature was observed at T_C = 352.5 K, and the free energy of activation (ΔG^#) for this process is 75.6 ± 2 kJ.mol^?1.

GRAPHICAL ABSTRACT     

Theoretical Study of Phenol Adsorption on Pristine, Ga-Doped, and Pd-Decorated (6,0) Zigzag Single-Walled Boron Phosphide Nanotubes

Phenol adsorption on the external surface of H-capped pristine, Ga-doped, and Pd-decorated (6,0) zigzag boron phosphide nanotubes (BPNTs) was studied by using density functional theory (DFT) calculations. The results indicate that the hydroxyl group of phenol prefers to attach to the Ga and Pd sites and thus the Ga-doped and Pd-decorated (6,0) can be used for removing phenol. The calculated adsorption energy of phenol on the Ga-doped and Pd-decorated (6,0) BPNTs are ?0.724 and ?420 eV, respectively and about 0.28 and 0.27 electrons are transferred from phenol to the nanotubes. In addition, the value for the fractional number of electrons transferred is negative, indicating that phenol act as an electron donor. Frontier molecular orbital theory (FMO) and structural analyses show that the high polar surface bonds and large bond lengths of the Ga-doped and Pd-decorated (6,0) BPNT surfaces increase the adsorption of phenol on the nanotube models. This study can be useful in removing phenol and development of many catalytic processes for formation of a variety of useful compounds.     

Kinetic-spectrophotometric determination of trace amounts of silver using the oxidation of thionine with peroxodisulfate.

A simple, rapid and sensitive method has been developed for determination of traces of silver(I) (0.2 - 13 ng mL(-1)) based on its catalytic effect on the oxidation of thionine by peroxodisulfate in the presence of 1 - 10 phenanthroline as an activator. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of thionine at 600 nm by the fixed time method. The detection limit is 0.098 ng mL(-1) and the relative standard deviation for 0.5, 3.0, 5.0 and 10 ng ml(-1) Ag(I) are 4.1, 1.37, 1.06 and 0.64%, respectively. The method is free from most interferences and it was applied to determination of silver in photographic solutions and well-water samples.