Magnetic ion imprinted polymer nanoparticles for the preconcentration of vanadium(IV) ions

An ion imprinted polymer coated onto magnetite (Fe₃O₄) nanoparticles is shown to be a useful magnetic sorbent for the fairly selective preconcentration of vanadium. The sorbent was prepared by radical copolymerization of 3-(triethoxysilyl)propyl methacrylate (the monomer), ethylene glycol dimethacrylate (the cross-linker), and the vanadium(IV) complex of 1-(2-pyridylazo-2-naphthol) in the presence of magnetite nanoparticles. The material was characterized by IR spectroscopy, scanning electron microscopy, and thermal analysis. The vanadium(IV) ions were removed from the imprint by a solution containing thiourea and HCl, and the eluent was submitted to AAS. The analytical efficiency and relative standard deviation are 99.4 and ±2.3 %, respectively, under optimum conditions, and the limit of detection is 20 ng mL^?1. The method was successfully applied to the preconcentration and determination of vanadium(IV) ions in crude oil. Figure

An ion imprinted polymer is coated on to magnetite nanoparticles as a useful magnetic sorbent for the fairly selective preconcentration of vanadium which can be used for vanadium determination in crude oil.     

Preconcentration of ultra-trace amounts of iron and antimony using ion pair solid phase extraction with modified multi-walled carbon nanotubes

Ion pair solid phase extraction was applied to the simultaneous preconcentration of iron and antimony. The ion pairs consisting of FeCl₄ ^? or SbCl₄ ^? anions and the benzyldimethyltetradecyl ammonium cation were formed on the surface of multi-walled carbon nanotubes, then eluted with nitric acid, and the elements finally quantified by ETAAS. The adsorption capacities of the impregnated MWCNTs are 9.2 mg g^?1 for iron and 27.5 mg g^?1 for antimony. The following analytical figures of merit were determined for iron and antimony, respectively: Enrichment factors of 210 and 230, assay precisions of ±5.3 % and ±4.8 %, linear calibration plots from 0.7 to 9.4 and 13.0 to 190 ng L^?1, and detection limits of 0.17 and 3.5 ng L^?1. The method was applied to the determination of iron and antimony in human hair, synthetic sample, and to the certified reference materials gold ore (MA-1b) and trace elements in water (SRM 1643d).

An efficient synthesis of 1-thioamidoalkyl-2-naphthol derivatives

The discovery and development of phosphorus pentoxide supported on silica gel (P₂O₅–SiO₂) as an efficient catalyst has led to an efficient method for the direct preparation of 1-thioamidoalkyl-2-naphthol derivatives in high yields by one-pot, three-component reaction of β-naphthol, aryl aldehydes, and thiourea or N-phenylthiourea at 100 °C under solvent-free conditions. In addition to its simplicity, this method has the ability to prepare a wide variety of the desired products.     

Brønsted acidic ionic liquids catalyze the preparation of 2,3-dihydroquinazolin-4(1H)-one derivatives

A simple and facile method for the green synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives by direct three-component cyclo-condensation of isatoic anhydride, ammonium acetate (or primary amines), and arylaldehydes using different Brønsted acidic ionic liquids, for example 2-pyrrolidonium hydrogensulfate ([hnmp][HSO₄]), N-methyl-2-pyrrolidonium hydrogensulfate ([NMP][HSO₄]), and N-methyl-2-pyrrolidonium dihydrogenphosphate ([NMP][H₂PO₄]), as reusable catalysts under solvent-free conditions is described. In addition, reaction of anthranilamide and arylaldehydes for synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives was investigated.     

Brønsted acidic ionic liquids catalyzed the preparation of 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraones and 3,4-dihydro-1H-benzo[b]xanthene-1,6,11(2H,12H)-triones

An environmentally green method for the synthesis of 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone and 3,4-dihydro-1H-benzo[b]xanthene-1,6,11(2H,12H)-trione derivatives using Brønsted acidic ionic liquids, 3-methyl-1-sulfonic acid imidazolium chloride, 1-H-3-methyl-imidazolium hydrogensulfate, triethylamine-bonded sulfonic acid, and triethylammonium hydrogensulfate as reusable catalysts under thermal solvent-free conditions is described.     

Bioassay and bioactivity of polymer as carrier for some active compounds such as anticancer drugs

The present work deals with the development of a new slow release polymeric material, based on maize starch/cellulose acetate blend polymerized with acrylic acid monomer by free-radical mechanism. The polymerization was initiated by a redox system. The synthesized polymeric material may be used as a carrier for some active compounds such as anticancer drugs and has been characterized by Fourier transform spectroscopy. The active compounds are a new series of heterocyclic derivatives that had an anticancer effect and were prepared from pyrimidine and coumarin compounds, namely: 7-(2-methoxyphenyl)-5-thioxo-5,6-dihydro[1,2,4]triazolo[4,3-c] pyrimidine-8-carbonitrile (compound I), 8-(2-methoxyphenyl)-3,4-dioxo-6-thioxo-3,4,6,7-tetrahydro-2h-pyrimido[6,1-c]-[1,2,4]triazine-9-carbonitrile (compound II), and 4-substituted-1-(1-(7-methoxy-4-methyl-coumarin-8-yl) ethylidene) thiosemi-carbazide (compound III). They were incorporated into the prepared polymer matrix. The polymer-carried drug was tested for slow release drug delivery through testing it in aqueous media for different time periods and examining it as an anti-proliferative agent against human liver cancer cell line (HEPG2). The release rate of the drug was evaluated in aqueous media at different pHs as well as in dimethyl formamide which is the good solvent of such drugs. The release was measured spectrophotometrically. It was found that the release rate depends on the pH of the aqueous media. The release of the drug in the alkaline media was found to be high compared with other media. Also, the sustained release of the drug was extended to about 20 days. The activity of the released drug against human liver cancer cell line was tested. The results showed that compound (III) gave the highest growth inhibition activity followed by compound (II), while compound (I) indicated the lowest activity against the human liver (HEPG2) cancer cell line.     

Pentameric Thiophene‐Based Ligands that Spectrally Discriminate Amyloid‐β and Tau Aggregates Display Distinct Solvatochromism and Viscosity‐Induced Spectral Shifts

A wide range of neurodegenerative diseases are characterized by the deposition of multiple protein aggregates. Ligands for molecular characterization and discrimination of these pathological hallmarks are thus important for understanding their potential role in pathogenesis as well as for clinical diagnosis of the disease. In this regard, luminescent conjugated oligothiophenes (LCOs) have proven useful for spectral discrimination of amyloid‐beta (Aβ) and tau neurofibrillary tangles (NFTs), two of the pathological hallmarks associated with Alzheimer’s disease. Herein, the solvatochromism of a library of anionic pentameric thiophene‐based ligands, as well as their ability to spectrally discriminate Aβ and tau aggregates, were investigated. Overall, the results from this study identified distinct solvatochromic and viscosity‐dependent behavior of thiophene‐based ligands that can be applied as indices to direct the chemical design of improved LCOs for spectral separation of Aβ and tau aggregates in brain tissue sections. The results also suggest that the observed spectral transitions of the ligands are due to their ability to conform by induced fit to specific microenvironments within the binding interface of each particular protein aggregate. We foresee that these findings might aid in the chemical design of thiophene‐based ligands that are increasingly selective for distinct disease‐associated protein aggregates.     

Electrospun polyamide–polyethylene glycol nanofibers for headspace solid‐phase microextration

A solution of polyamide (PA) containing polyethylene glycol (PEG) as a side low‐molecular‐weight polymer was electrospun. After synthesizing the PA–PEG nanofibers, the constituent was subsequently removed (modified PA) and confirmed by Fourier transform infrared spectroscopy. The scanning electron microscopy images showed an average diameter of 640 and 148 nm for PA and PA–PEG coatings, respectively, while the latter coating structure was more homogeneous and porous. The extraction efficiencies of PA, PA–PEG, and the modified PA fiber coatings were assayed by headspace solid‐phase microextraction of a number of chlorophenols from real water samples followed by their determination by gas chromatography with mass spectrometry. To prepare the most appropriate coatings, the amounts and the flow rate of the electrospinning solution were investigated. Various extraction parameters, such as the salt content, desorption condition, extraction temperature, and time were optimized. The limits of detection of the method were in the range of 0.8–25 ng/L, while the RSDs at two concentration levels of 200 and 80 ng/L were between 2.1 and 12.2%. The analysis of real water samples led to relative recoveries between 85 and 98% with a linearity of 8–1500 ng/L.     

Experimental and theoretical characterization of Co(III) and Zn(II) complexes with phenol-based hexa-dentate macro-acyclic ligands: synthesis,density functional theory and time-dependent density functional theory studies

Macro-acyclic complexes with two dissimilar coordination sites: one includes six coordination set (N₄O₂) and the other a tetradentate donor set (N₂O₂) of the type [Co^IIIL^en]ClO₄ and [Co^IIIL^tn]ClO₄ (where L^en = N,N′-bis(pyridine-2-ylmethyl)-N,N′-bis(5-bromo-3-formyl-2-hydroxybenzyl)-1,2-diaminoethane and L^tn = N,N′-bis(pyridine-2-ylmethyl)-N,N′-bis(5-bromo-3-formyl-2-hydroxybenzyl)-1,3-diaminoepropane) have been synthesized and characterized. Characterization result revealed that in the synthetic procedure of [Co^IIIL^en]ClO₄ only an isomer (trans-pyridine/cis-phenolate) among three possible geometrical isomers is formed. However, synthesis of its counterpart, [Co^IIIL^tn]ClO₄ resulted in the formation of a mixture of geometrical isomers (trans-pyridine/cis-phenolate and cis-pyridine/cis-phenolate). The computational studies of these complexes demonstrated that in [Co^IIIL^tn]⁺ an equilibrium exists between two possible geometrical isomers as result of a small energy difference (0.72 kcal mol^?1), whereas in [Co^IIIL^en]⁺ the difference is (2.71 kcal mol^?1). Furthermore, [Zn^IIL^en] has been studied computationally and experimentally by IR, UV–Vis spectroscopy techniques. The results showed that it has a similar structure to [Co^IIIL^en]⁺ complex. Electronic spectra of the complexes were analyzed and the absorption bands were assigned through the density functional theory (DFT) and time-dependent density functional theory (TD–DFT) studies procedures. The molecular orbital diagrams of the complexes were also determined.     

[Bmim]N3 as an efficient reagent for the Schmidt reactions of ketones,arylaldehydes and aromatic carboxylic acids

Schmidt reaction of arylaldehydes, ketones and aromatic carboxylic acids using task-specific ionic liquid, [bmim]N₃ in the presence of AcOH/H₂SO₄ proceeds at 50–60 °C within 2–4 h to give the corresponding products. Benzaldehydes containing electron releasing groups afforded to the related benzamide derivatives. Benzonitrile derivatives were formed from the reaction of benzaldehydes containing electron withdrawing groups under these conditions. High yields of the related amides and anilines were obtained from the reaction of a variety of ketones and aromatic carboxylic acids, respectively, utilizing this procedure.