Polymeric catalyst for the synthesis of new pyrido[2,3-b]indoles

A new and efficient method has been developed for the one-pot synthesis of novel 2,9-dihydro-2-oxo-4-aryl-1H-pyrido[2,3-b]indole-3-carbonitrile derivatives by condensation of substituted (triethoxymethyl)arene, 1-methyl-1H-indol-2-ol and cyanoacetamide in the presence of a catalytic amount of crosslinked poly(2-acrylamido-2-methyl propane sulfonic acid) (AMPS) as an efficient and heterogeneous catalyst. This polymeric solid acid catalyst is stable and can be easily recovered and reused without significant change in its activity.     

Low Temperature Preparation of 3D Solid and Hollow ZnS Nanosphere Self-Assembled from Nanoparticles by Varying Sulfur Source

In this work, we report a facile hydrothermal method for the preparation of three dimensional hollow ZnS nanostructures, using Zinc bis(salicyle aldehitato), Zn(Sal)₂, thioacetamide (TAA) and thioglycolic acid (TGA) as Zn²⁺, sulfur source and capping agent, respectively. The ZnS solid and hollow sphere was produced from the self-assembly of nanoparticles with diameters of 11 ± 2 nm with TGA and TGA, TAA, respectively. Furthermore, with changing zinc precursor from Zn(Sal)₂ to zinc acetate [Zn(OAC)₂], ZnS nanorods were obtained. The products were characterized by XRD, SEM, TEM, selected area electron diffraction, and FT-IR spectra. The influence of surfactant (Polyethylene glycol) on the morphology of the products was also investigated. Possible formation mechanism and optical properties of these architectures were also reported.     

Photoelectrocatalytic degradation of 3-nitrophenol at surface of Ti/TiO2 electrode

The widely utilization of phenol and its derivatives such as 3-nitrophenol (3-NP) has led to the worldwide pollution in the environment. In this study, Ti/TiO₂ photoelectrode was prepared with anodic oxidation of Ti foil electrode and then the photoelectrocatalytic (PEC) degradation of 3-NP was performed via this electrode, comparing with photocatalytic (PC), electrooxidation and direct photolysis by ultraviolet light. A significant photoelectrochemical synergetic effect in 3-NP degradation was observed on the Ti/TiO₂ electrode and rate constant for the PEC process of Ti/TiO₂ electrode was about three times as high as its PC degradation process. 3-NP concentration monitoring was carried out with differential pulse voltammetry. Results showed that PEC degradation has highest effect on concentration decreasing of 3-NP at solution and degraded it about 38 %, while other processes degradation efficiencies were about 4, 7, and 12 % for electrooxidation, direct photolysis and photocatalytic degradation, respectively. Finally, effects of solution pH and applied potential on degradation efficiency were studied and results showed that optimum pH for degradation is equal 4.00 and optimum potential is 1.2 V vs. Ag|AgCl|KCl (3M) reference electrode.     

Investigation of the equality constraint effect on the reduction of the rotational ambiguity in three-component system using a novel grid search method

The obtained results by soft modeling multivariate curve resolution methods often are not unique and are questionable because of rotational ambiguity. It means a range of feasible solutions equally fit experimental data and fulfill the constraints. Regarding to chemometric literature, a survey of useful constraints for the reduction of the rotational ambiguity is a big challenge for chemometrician. It is worth to study the effects of applying constraints on the reduction of rotational ambiguity, since it can help us to choose the useful constraints in order to impose in multivariate curve resolution methods for analyzing data sets. In this work, we have investigated the effect of equality constraint on decreasing of the rotational ambiguity. For calculation of all feasible solutions corresponding with known spectrum, a novel systematic grid search method based on Species-based Particle Swarm Optimization is proposed in a three-component system.     

A study of peroxyoxalate-chemiluminescence of acriflavine

The chemiluminescence arising from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with hydrogen peroxide in the presence of acriflavine has been studied. The relationship between the chemiluminescence intensity and concentrations of TCPO, H2O2, acriflavine and the base sodium salicylate are reported. The kinetic parameters for the peroxyoxalate-chemiluminescence (PO-CL) of acriflavine were evaluated from the computer fitting of the corresponding chemiluminescence intensity-time plots.     

Rice Bran as an Excellent Sorbent for Heavy Metals from Aqueous Media, 1. Optimization of Conditions

In this two‐part report, the efficiency of rice bran in removal of heavy metals such as cadmium, lead, zinc, nickel, copper and iron(III) from aqueous solution is investigated. The different experimental conditions such as pH, temperature, volume of solution, bran amount, particle size, exchange time, stirring speed, etc. are studied, and the optimum conditions are selected in part 1 of this series of reports. The efficiency of bran in removal of heavy metals is presented with and without treatments. For treatment, heat or acid, alkali and salt solutions were used. The results obtained show that after treating with saturated sodium chloride solution, its efficiency for Ni²⁺ and Zn²⁺ improves. At pH 5, all studied cations have recoveries more than 93% (lead and cadmium 100%). The exchange speed is very high and has preference over the classical ion exchangers.     

Sonochemical Synthesis and Photocatalytic Properties of Metal Hydroxide and Carbonate (M:Mg, Ca, Sr or Ba) Nanoparticles

In this work Mg(OH)₂, Ca(OH)₂, CaCO₃, SrCO₃ and BaCO₃ nanoparticles were synthesized via a simple sonochemical reaction at room temperature. Nanoparticles were synthesized via a surfactant-free reaction solvent water. Nanostructures materials were characterized by scanning electron microscopy, X-ray diffraction and fourier transform infrared spectroscopy. The photocatalytic behavior of nanoparticles was evaluated using the degradation of a methyl orange aqueous solution under ultraviolet light irradiation. The results show that metal hydroxide and metal carbonate nanoparticles are promising materials with excellent performance in photocatalytic applications.     

Bulk polymer nanoparticles containing a tetrakis(3-hydroxyphenyl)porphyrin for fast and highly selective separation of mercury ions

We report on the synthesis of polymeric nanoparticles (PNPs) containing a tetrakis(3-hydroxyphenyl)porphyrin, and their use for the separation of mercury(II) ion. The PNPs were prepared by bulk polymerization from methacrylic acid (the monomer), ethyleneglycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the radical initiator) and the mercury(II) complex of 5,10,15,20-tetrakis(3-hydroxyphenyl)-porphyrin. The Hg(II) ion was then removed by treatment with dilute hydrochloric acid. The PNPs were characterized by colorimetry, FT-IR spectroscopy, and scanning electron microscopy. The material is capable of binding Hg(II) from analyte samples. Bound Hg(II) ions can be eluted with dilute nitric acid and then quantified by cold vapor AAS. The extraction efficiency, the effects of pH, preconcentration and leaching times, sample volume, and of the nature, concentration and volume of eluent were investigated. The maximum adsorption capacity of the PNPs is 249 mg g^?1, the relative standard deviation of the AAS assay is 2.2 %, and the limit of detection (3σ) is 8 ng.L^?1. The nanoparticles exhibit excellent selectivity for Hg(II) ion over other metal ions and were successfully applied to the selective extraction and determination of Hg(II) ion in spiked water samples.

β-Cyclodextrin conjugated magnetic nanoparticles as a novel magnetic microvessel and phase transfer catalyst: synthesis and applications in nucleophilic substitution reaction of benzyl halides

This paper presents a feasible protocol for the preparation of β-cyclodextrin conjugated Fe₃O₄ magnetic nanoparticles as an efficient microvessel and host system for nucleophilic substitution reaction of benzyl halides in water. No evidence for the formation of by-product for example isothiocyanate or benzyl alcohol was observed and the products were obtained in pure form without further purification. The characteristics results of FT-IR, XRD, TGA and SEM shows that β-CD is grafted onto Fe₃O₄ nanoparticles. The nanomagnetic catalyst could be readily separated from solution via application of an external magnet, allowing straightforward recovery and reuse.