A hyperbranched polyamidoamine dendrimer grafted onto magnetized graphene oxide as a sorbent for the extraction of synthetic dyes from foodstuff

Microchimica Acta - Graphene oxide nanosheets were modified with magnetite nanoparticles, and a hyperbranched polyamidoamine dendrimer was then covalently attached to their surface. The resulting...     

Solid-phase Extraction and High Performance Liquid Chromatographic Determination of Folic Acid in Fortified Foodstuffs: a Recommended Process Utilizing a New Strong Anion Exchange Sorbent

Journal of Analytical Chemistry - A highly efficient solid-phase extraction (SPE) column filled with a silica-based strong anion exchange sorbent was reported in the current study. The fabricated...     

Insertion of tin(II) bromide into Pt–X (X = Cl,Br) bond of dimethylplatinum(IV) complexes: A novel polymorphic form of [PtBr2(bpy)]

The platinum(II) complex [PtMe₂(bpy)] (bpy = 2,2′-bipyridine) reacted with a large excess of dihaloalkanes X(CH₂)_nX (n = 1, X = Cl; n = 4, X = Br) to form the platinum(IV) complexes [PtMe₂X{(CH₂)_nX}(bpy)] (n = 1, X = Cl, 1a; n = 4, X = Br, 1b). The reaction of complexes 1a and 1b with SnBr₂ resulted in insertion of SnBr₂ into Pt–X (X = Cl, Br) bond to afford the trihalostannyl complexes [PtMe₂(SnBr₂X){(CH₂)_nX}(bpy)] (n = 1, X = Cl, 2a; n = 4, X = Br, 2b). The synthesis of such trihalostannylplatinum(IV) complexes is reported for the first time. The complex 2a was decomposed in CH₂Cl₂ solution and single crystals of [PtBr₂(bpy)] (3a) were obtained. The X-ray structure determination of 3a revealed a new polymorphic form of [PtBr₂(bpy)]. The molecules undergo a remarkable stacking along the b-axis to form a zigzag Pt?Pt?Pt chain containing both short (3.799 Å) and long (5.175 Å) Pt?Pt separations through the crystal. The crystal structure is compared to that of the yellow modification of [PtBr₂(bpy)].     

Catalyst-free,aqueous and highly diastereoselective synthesis of new 5-substituted 1H-tetrazoles via a multi-component domino Knoevenagel condensation/1,3 dipolar cycloaddition reaction

An approach for the synthesis of new 5-substituted-tetrazoles via multi-component domino Knoevenagel condensation/1,3 dipolar cycloaddition reaction of carbonyl compounds, malononitrile and sodium azide in water without assistance of any catalyst has been reported. This general protocol provides a wide variety of 5-substituted 1H-tetrazoles in good yields under mild reaction conditions.     

CO2 reforming of methane over nickel catalysts supported on nanocrystalline MgAl2O4 with high surface area

In this paper dry reforming of methane (DRM) was carried out over nanocrystalline MgAl2O4-supported Ni catalysts with various Ni loadings. Nanocrystalline MgAl2O4 spinel with high specific surface area was synthesized by a co-precipitation method with the addition of pluronic P123 triblock copolymer as surfactant, and employed as catalyst support. The prepared samples were characterized by X-ray diffraction (XRD), N2 adsorption, H2 chemisorption, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), temperature- programmed desorption (TPD) and transmission and scanning electron microscopies (TEM, SEM) techniques. The obtained results showed that the catalyst support has a nanocrystalline structure (crystal size: about 5 nm) with a high specific surface area (175 m2 g-1) and a mesoporous structure. Increasing in nickel content decreased the specific surface area and nickel dispersion. The prepared catalysts showed high catalytic activity and stability during the reaction. SEM analysis revealed that whisker type carbon deposited over the spent catalysts and increasing in nickel loading increased the amount of deposited carbon. The nickel catalyst with 7 wt% of nickel showed the highest catalytic activity.     

Lamellarins as Inhibitors of P‐Glycoprotein‐Mediated Multidrug Resistance in a Human Colon Cancer Cell Line

Chemical analysis of a Didemnum sp. (CMB‐01656) collected during scientific Scuba operations off Wasp Island, New South Wales, yielded five new lamellarins A1 ( 1 ), A2 ( 2 ), A3 ( 3 ), A4 ( 4 ) and A5 ( 5 ) and eight known lamellarins C ( 6 ), E ( 7 ), K ( 8 ), M ( 9 ), S ( 10 ), T ( 11 ), X ( 12 ) and χ ( 13 ). Analysis of a second Didemnum sp. (CMB‐02127) collected during scientific trawling operations along the Northern Rottnest Shelf, Western Australia, yielded the new lamellarin A6 ( 14 ) and two known lamellarins G ( 15 ) and Z ( 16 ). Structures were assigned to 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 on the basis of detailed spectroscopic analysis with comparison to literature data and authentic samples. Access to this unique library of natural lamellarins ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ) provided a rare opportunity for structure–activity relationship (SAR) investigations, probing interactions between lamellarins and the ABC transporter efflux pump P‐glycoprotein (P‐gp) with a view to reversing multidrug resistance in a human colon cancer cell line (SW620 Ad300). These SAR studies, which were expanded to include the permethylated lamellarin derivative ( 17 ) and a series of lamellarin‐inspired synthetic coumarins ( 19 , 20 , 21 , 22 , 23 , 24 ) and isoquinolines ( 25 , 26 ), successfully revealed 17 as a promising new non‐cytotoxic P‐gp inhibitor pharmacophore.     

A Novel Hydrogen Peroxide Sensor Based on the Direct Electron Transfer of Catalase Immobilized on Nano‐Sized NiO/MWCNTs Composite Film

MWCNTs‐nanoNiO composite was used as a glassy carbon electrode modifier for construction of a novel catalase nanobiosensor for hydrogen peroxide. The immobilized catalase exhibited excellent electrocatalytic activity towards the reduction of H₂O₂. The resulting amperometric biosensor exhibited a linear response over a concentration range of 200 µM to 2.53 mM with a low detection limit of 19.0 µM. Electrochemical impedance measurements revealed that the modified electrode can be used for the sensitive detection of H₂O₂. The charge transfer resistance found to decrease significantly after enzymatic reaction of nanobiosensor with H₂O₂. The resulting impedance was highly sensitive to H₂O₂ over a linear range of 19–170 nM with a detection limit of 2.4 nM.     

An Efficient Synthesis of 3‐(1H‐Tetrazol‐5‐yl)coumarins (=3‐(1H‐Tetrazol‐5‐yl)‐2H‐1‐benzopyran‐2‐ones) via Domino Knoevenagel Condensation,Pinner Reaction,and 1,3‐Dipolar Cycloaddition in Water

A novel straightforward synthesis of 3‐(1H‐tetrazol‐5‐yl)coumarins (=3‐(1H‐tetrazol‐5‐yl)‐2H‐1‐benzopyran‐2‐ones) 6 via domino Knoevenagel condensation, Pinner reaction, and 1,3‐dipolar cycloaddition of substituted salicylaldehydes (=2‐hydroxybenzaldehydes), malononitrile (propanedinitrile), and sodium azide in H₂O is reported (Scheme 1 and Table 2). This general protocol provides a wide variety of 3‐(1H‐tetrazol‐5‐yl)coumarins in good yields under mild reaction conditions.     

Synthesis of colloidal nanoscaled copper-indium-gallium-selenide (CIGS) particles for photovoltaic applications

In this work, Cu(In,Ga)Se(2) (CIGS) nanoparticles were synthesized using a wet chemical method. The method is based on a non-vacuum thermal process that does not use selenization. The effects of temperature, source materials, and growth conditions on the phase and particle size were investigated. X-ray diffraction results confirm the formation of a tetragonal CIGS structure as the main phase with the purity more than 99% obtained by energy-dispersive X-ray spectroscopy (EDX). The morphology and size of the samples were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using these methods, 20-80nm particles were obtained. Through measurements of the absorption spectra of CIGS nanoparticles, the band gap of the synthesized material was determined to be about 1.44eV, which corresponds to an acceptable wavelength region for absorber layers in solar cells.