Step-by-step synthesis of copper(I) complex supported on platinum nanoparticle-decorated mesoporous silica hollow spheres and its remarkable catalytic performance in Sonogashira coupling reaction

In this study, a step-by-step method for the synthesis of platinum nanoparticles and copper(I) complex supported on mesoporous silica hollow spheres (Pt-MSHSs-Cu) is introduced. Scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption, energy-dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, and elemental and thermogravimetric analyses were applied for characterization of the surface, structure, size, phase composition, and morphology of the synthesized materials. The characterized material, Pt-MSHSs-Cu, was used as an efficient and heterogeneous catalyst in the Sonogashira coupling reaction under different reaction conditions. In comparison with MSHSs, Cu(I)-functionalized MSHSs (MSHSs-Cu), and Pt-MSHSs samples, the Pt-MSHSs-Cu catalyst exhibited significantly increased catalytic performance with 91.50% yield. Therefore, the results obtained suggested a synergistic effect derived from platinum nanoparticles, MSHSs substrate, and copper(I) complex, which enhanced the rate of the Sonogashira coupling reaction.     

One-pot synthesis of 2-amino-3-cyanopyridines and hexahydroquinolines using eggshell-based nano-magnetic solid acid catalyst via anomeric-based oxidation

Research on Chemical Intermediates - In the present research, the eggshell as a hazardous waste by European Union regulations was converted to a valuable catalyst, namely nano-Fe3O4@(HSO4)2. The...     

Novel Complexes of Gallium(III), Indium(III), and Thallium(III) with Pyridine‐Containing Proton Transfer Ion Pairs Obtained from Dipicolinic Acid – Synthesis,Characterization and X‐ray Crystal Structure

Three new complexes of group thirteen metals, gallium(III), indium(III), and thallium(III) with proton transfer compounds, obtained from 2,6‐pyridinedicarboxylic acid (dipicolinic acid), were synthesized and characterized using elemental analysis, IR, ¹H and ¹³C NMR spectroscopy and single crystal X‐ray diffraction. The gallium(III) and indium(III) complexes were prepared using (pydaH₂)(pydc) (pyda = 2,6‐pyridinediamine, pydcH₂ = dipicolinic acid) and thallium(III) complex was obtained from (creatH)(pydcH) (creat = creatinine). The chemical formulae and space groups of the complexes are (pydaH)[Ga(pydc)₂] · 3.25H₂O · CH₃OH, ( 1 ), [In(pydc)(pydcH)(H₂O)₂] · 5H₂O, Pna2₁ ( 2 ) and [Tl₂(pydcH)₃(pydc)(H₂O)₂], ( 3 ). Non‐covalent interactions such as ion‐pairing, hydrogen bonding and π‐π stacking are discussed. The complexation reactions of pyda, pydc, and pyda + pydc with In³⁺ and Ga³⁺ ions in aqueous solution were investigated by potentiometric pH titrations, and the equilibrium constants for all major complexes formed are described.     

Interference of the electrospray voltage on chromatographic separations using porous graphitic carbon columns

The electrospray ionization (ESI) voltage is shown to interfere with liquid chromatographic separations performed with packed porous graphitic carbon (PGC) capillary columns. This interference is ascribed to the presence of an electric field over the conductive column in the absence of an earth point between the column and the ESI emitter. The current evolved alters the chromatographic behavior of the catecholamine metabolite 3-O-methyl-DOPA significantly, as both peak splitting and a dramatic decrease in the retention time were observed. Furthermore, the response from the mass spectrometer was decreased by 33% at the same time. A related compound, tyrosine, exhibited decreased retention times but no peak splitting, whereas no shifts in the retention times (or peak splitting) were seen for the less retained dopamine and noradrenaline. When the current through the PGC column was eliminated by the use of an earth point between the column and the ESI emitter, the chromatographic behavior of the column was found to return slowly to normal after hours of equilibration with 60 : 40 (v/v) methanol-ammonium formate buffer of pH 2.9. The behavior of the PGC column with and without the earth point was found to be highly reproducible during a period of 1 month. We propose that the effect of the ESI voltage on the chromatographic behavior of the PGC column is due to associated redox reactions affecting both the PGC particles and the analytes. It is concluded that (for analytical reasons), care should be taken to ensure that no current is flowing through the chromatographic system when interfacing PGC columns, and conducting parts in general, to ESI mass spectrometry.     

Selective Method for the Conversion of Oximes to Their Corresponding Carbonyl Compounds under Microwave Irradiation by N‐Bromo‐N‐Phenyl‐Para‐Toluenesulfonamide

In this work, oximes are converted to their corresponding carbonyl compounds in good yields using N‐bromo‐N‐phenyl‐para‐toluenesulfonamide, under microwave irradiation. The simple work‐up procedure minimizes loss of product.     

On the sphericity testing of single source digraphs

A digraph D=(V,A) is called spherical, if it has an upward embedding on the round sphere which is an embedding of D on the round sphere so that all edges are monotonic arcs and all point to a fixed direction, say to the north pole. It is easy to see that [S.M. Hashemi, Digraph embedding, Discrete Math. 233 (2001) 321-328] for upward embedding, plane and sphere are not equivalent, which is in contrast with the fact that they are equivalent for undirected graphs. On the other hand, it has been proved that sphericity testing for digraphs is an NP-complete problem [S.M. Hashemi, A. Kisielewicz, I. Rival, The complexity of upward drawings on spheres, Order 14 (1998) 327-363]. In this work we study sphericity testing of the single source digraphs. In particular, we shall present a polynomial time algorithm for sphericity testing of three connected single source digraphs.     

Magnetic, structural and micro-structural properties of mechanically alloyed nano-structured Fe48Co48V4 powder containing inter-metallic Co3V

The Fe₄₈Co₄₈V₄ alloy was synthesized in a planetary high-energy ball-mill under an argon atmosphere. The structure, microstructure and magnetic properties of the mechanically alloyed powders were investigated by X-ray diffraction, Scanning Electron Microscopy and a Vibration Sample Magnetometer, respectively. During the mechanical alloying of Fe₄₈Co₄₈V₄, inter-metallic Co₃V appears. The lattice parameter decreases up to 55 h of milling time with an oscillation and then increases from 55 to 125 h of milling time. The coercivity increases during the milling treatment from 49 to 58 Oe. The saturation magnetization has some fluctuations during the milling treatment and finally reaches ∼190 emu/g at 125 h.     

新型磺酸功能化吡啶盐酸盐离子液体催化剂用于六氢喹啉合成(英文)

Sulfonic acid functionalized pyridinium chloride [pyridine-SO3 H]Cl has been synthesized as a novel Brnsted acidic ionic liquid and characterized on the basis of its FT-IR,1H and 13C NMR,MS,ther-mogravimetry,and derivative thermogravimetry data.The material has also been used as a highly efficient,homogeneous,and reusable catalyst for the preparation of hexahydroquinolines according to the one-pot multi-component condensation of arylaldehydes,dimedone(5,5-dimethylcyclohexane-1,3-dione),β-ketoesters,and ammonium acetate under solvent-free conditions.