Efficient Sonogashira and A3 coupling reactions catalyzed by biosynthesized magnetic Fe3O4@Ni nanoparticles from Euphorbia maculata extract

In this work, biosynthesized Fe₃O₄@Ni nanoparticles using Euphorbia maculata aqueous have been used as effective catalysts in the synthesis of 2,3-disubstituted benzo[b]furan derivatives using three component coupling of aldehydes, secondary amines and alkynes (A³ coupling reaction). Using novel nanoscale materials, the current green, practical and economical method leads to short reaction times and high yields. The biosynthesized catalyst was also successfully employed in the Sonogashira cross-coupling reactions of various aryl halides with phenylacetylene. The best performance was observed using just 20 mg of the catalyst and ethanol as a green solvent. The developed protocol provides easy workup, short reaction times and good to excellent product yields. Furthermore, since the composite is highly stable, an external permanent magnet can be easily used for separating the catalyst. Thus, the catalyst can be recycled several times without considerable loss of catalytic activity.     

Electrocatalytic and Simultaneous Determination of Ascorbic Acid,Nicotinamide Adenine Dinucleotide and Folic Acid at Ruthenium(II) Complex‐ZnO/CNTs Nanocomposite Modified Carbon Paste Electrode

This paper describes the development a novel ruthenium(II) complex‐ZnO/CNTs modified carbon paste electrode (Ru(II)/ZnO/CNTs/CPE) for the electrocatalytic determination of ascorbic acid (AA). The objective of this novel electrode modification was to seek new electrochemical performances for the detection of AA, nicotinamide adenine dinucleotide (NADH) and folic acid (FA). The peak potentials recorded were 170, 500 and 830 mV vs. Ag/AgCl/KCl_sat for AA, NADH and FA, respectively. The peak currents were linearly dependent on AA, NADH and FA concentrations using square wave voltammetry (SWV) method at the ranges of 0.008–251, 1.0–650, and 3.0–700 µmol L^?1, with detection limits of 0.005, 0.5, and 1.0 µmol L^?1, respectively.     

Investigation of Yb(III)-PVC membrane interfacial interaction by semiempirical PM6/SPARKLE method based on 1,10-phenanthroline-5,6-dione as a suitable neutral ionophore

The initiation of atherosclerosis involves retention of colloidal atherogenic lipoproteins, primarily low density lipoprotein (LDL), in the arterial intima. This retention occurs when LDL binds to smooth muscle cell extracellular matrix (SMC ECM), and is enhanced by lipoprotein lipase (LpL) and sphingomyelinase (Smase). Here we use a fluorescence assay and dynamic light scattering to study the individual and combined effects of these two enzymes on LDL aggregation. Our results show: (1) LpL is self-sufficient to induce LDL aggregation with aggregate sizes up to ~400 nm; (2) Smase induces LDL aggregation due to generation of ceramide and subsequent hydrophobic interactions; (3) Smase hydrolysis of LpL-induced LDL aggregates does not cause further aggregation and results in a ~3-fold diminished production of ceramide, while LpL treatment of Smase-induced aggregates does enhance aggregation; (4) The simultaneous addition of LpL and Smase causes increased variability in aggregation with final sizes ranging from 50 to 110 nm. Our data suggest a new proatherogenic function for LpL, namely, bridging between LDL particles causing their aggregation and consequently enhanced retention by SMC ECM. The mechanism of LpL-and-Smase-mediated LDL aggregation and binding to SMC ECM provides specific points of intervention to design novel effective antiatherogenic therapeutics.     

Magnetite-silica nanoparticles with core-shell structure: single-step synthesis,characterization and magnetic behavior

In this study, a specific technique was used to quickly, easily, and single step, synthesize core-shell magnetite-silica nanoparticles by controlling the reaction conditions using the proper surfactant. In the first step, the magnetite nanoparticles were prepared by co-precipitation method and silica shell was immediately formed by the sol-gel process. Synthesis was performed at 80?°C with stirring at 12,000?rpm in an alkaline medium. The structural and morphological characteristics of core-shell nanoparticles were examined by XRD, TEM, SEM, and BET analyses. In addition, vibrating sample magnetometer (VSM) was used to evaluate the magnetic characteristics. XRD analysis confirmed the existence of both magnetite and silica phases in the final structure. TEM images showed the presence of nanocomposite particles with core-shell structure of 25?nm diameter. The mean core and shell size were estimated to be about 20 and 2.5?nm, respectively. A study of the magnetic characteristics showed super-paramagnetic behavior with 60?emu/g saturation magnetization (M_s). Due to the high ratio of core size to shell thickness, the magnetic saturation for the synthetized core-shell nanoparticles in this research was significant. In comparison to other multi-step synthesis techniques, the results obtained from this research confirmed the formation of magnetite-silica core-shell structures with the desired magnetic behavior in a quick and single-step process.

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Mononuclear nickel(II) complexes coordinated by polypyridyl ligands

Three mononuclear polypyridyl complexes of Ni(II), [Ni(Ph₂phen)₃](PF₆)₂·CH₃CN (1), [Ni(dpa)₂(phen)](PF₆)₂ (2) and [Ni(bpy)₃](PF₆)₂ (3), where Ph₂phen is 4,7-diphenyl-1,10-phenanthroline, dpa is 2,2′-dipyridylamine, bpy is 2,2′-bipyridine, and phen is 1,10-phenanthroline, were prepared and their solid state structures determined by single-crystal X-ray crystallography. The structural determination shows that the coordination geometry around the Ni(II) center is a distorted octahedron in each complex. The investigation of synthesis procedure and crystallographic data of complex 3 indicates the spontaneous resolution of supramolecular chirality. A careful inspection of the packing pattern in the lattice of each complex reveals that non-covalent interactions of two different types, viz. C-H?F and C-H?π interactions, are active in the lattice. The packing structures of 1-3 also show that the rings of the polypyridyl ligands, Ph₂phen, dpa, bpy, and phen, are not located face-to-face and can not interact through π-π interactions. Cyclic voltammetry data of 1 and 3 show that the Ni(III/II) reduction couple is quasi-reversible and this reduction becomes progressively more difficult on passing from bpy to Ph₂phen, while complex 2 shows an irreversible behavior with the peak-to-peak separation of about 500 mV. Magnetic susceptibility data derived from paramagnetic NMR revealed effective magnetic moments of 3.12 BM for 1, 3.27 BM for 2, and 3.14 for 3 at room temperature.     

Rhodium(III) and cadmium(II) complexes based on the polypyridyl ligand 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz)

Tppz (2,3,5,6-tetrakis(2-pyridyl)pyrazine) complexes [Rh(tppz)(bpy)Cl][PF₆]₂.acetylacetone (bpy = 2,2′-bipyridine) and [{CdCl₂}₂(μ-tppz)].ethylene glycol have been synthesized and characterized by elemental analyses, IR, ¹H NMR, cyclic voltammetry, photoluminescence and electronic spectral studies. Solid state structures of both complexes have been determined by single-crystal X-ray crystallography. The structural determination shows that the dinuclear Cd(II) complex, [{CdCl₂}₂(μ-tppz)], is a 1D coordination polymer. An ORTEP drawing of [Rh(tppz)(bpy)Cl][PF₆]₂.acetylacetone shows that the coordination geometry around the Rh(III) center is a distorted octahedron. [{CdCl₂}₂(μ-tppz)] displays intraligand ¹(π–π^*) fluorescence and can potentially serve as a photoactive material. For the mononuclear Rh(III) complex, only a two-electron reduction process occurs at the metal with the elimination of Cl⁻ ligand. The emission of this complex is assigned as πd^* phosphorescence.     

Integrated data envelopment analysis and cooperative game for evaluating energy efficiency of transportation sector: a case of Iran

Annals of Operations Research - Transportation sector with the consumption of 25% of energy play a major role in Iranian economy. This sector produces 27% of total undesirable greenhouse gases in...