Superb catalytic properties of nickel cobalt bimetallic nanoparticles immobilized on 3D nitrogen-doped graphene for thermal decomposition of ammonium perchlorate

Research on Chemical Intermediates - Nickel cobalt bimetallic nanoparticles (NiCo NPs) with different molar ratios were stabilized over three-dimensional nitrogen-doped graphene [3D-(N)G] by a...     

Copper chromite decorated on nitrogen-doped graphene aerogel as an efficient catalyst for thermal decomposition of ammonium perchlorate particles

Journal of Thermal Analysis and Calorimetry - The present study reports numerical simulations of water-based Al2O3 nanofluid flowing in a 2D channel with a heated wall-mounted obstacle. The...     

Solvent bar microextraction combined with high‐performance liquid chromatography for preconcentration and determination of pramipexole in biological samples

A simple, rapid and sensitive analytical method for preconcentration and determination of pramipexole in different biological samples has been developed using solvent bar microextraction (SBME) combined with HPLC‐UV. The target drugs were extracted from 10 mL of basic aqueous sample solution into an organic extracting solvent located inside the pores of a polypropylene hollow fiber, then back‐extracted into an acidified aqueous solution in the lumen of the hollow fiber. In order to obtain high extraction efficiency, the effect of different variables on the extraction efficiency was studied simultaneously using an experimental design. The experimental parameters of SBME were optimized using a Box–Behnken design after a Plackett–Burman screening design. Under the optimized conditions, an enrichment factor up to 96 was achieved and the relative standard deviation of the method was 4.64% (n = 5). The linear range was 0.05–2000 µg/L with a correlation coefficient (r) of 0.987. Finally, the applicability of the proposed method was evaluated by extraction and determination of pramipexole in plasma and urine samples. The results indicated that SBME method has excellent clean‐up and high preconcentration factor and can serve as a simple and sensitive method for analysis of pramipexole in biological samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis of New Phosphonium Ylides Containing Thiophene and Furan Rings and Study of Their Reaction with Mercury(II) Halides: Spectral and Structural Characterization

Reactions of phosphonium ylides (4‐MeC₆H₄)₃PCHC(?O)(2‐C₄H₃S) (tptpy), Ph₃PCHC(?O)(2‐C₄H₃O) (fppy), and (4‐MeC₆H₄)₃PCHC(?O)(4‐BrC₆H₄) (bbtppy) with HgX₂ (X=Cl, Br, and I) in equimolar ratios in MeOH as solvent leads to the binuclear products 1 – 3 (Scheme 1). The bridge‐splitting reaction of the binuclear complex [{HgI₂(bbtppy)}₂] ( 3c ) by DMSO yields the mononuclear complex [HgI₂?(bbtppy) (DMSO)] ( 3d ) (Scheme 2). This bridge‐splitting reaction can also be a method for the synthesis of mononuclear products. C‐Coordination of the ylide and O‐coordination of DMSO are demonstrated by a single‐crystal X‐ray‐analysis of the mononuclear complex 3d . Characterization of the obtained compounds was also performed by means of elemental analysis and IR and ¹H‐, ³¹P‐, and ¹³C‐NMR spectroscopy. A theoretical study of some Hg^II complexes with phosphonium ylides is also reported.     

Biomimetic complexes-graphene composites for redox processes

Biomimetic complexes such as porphyrins, phthalocyanines, and hemins show promising catalytic activities in redox processes. Donor-acceptor hybrids of these biomimetic macrocyclic complexes with graphene as one of the most critical allotropes of carbon are currently an outstanding scientific frontier. Notably, the composites that consist of these efficient and bio-inspiring complexes anchored on the surface of the graphene and their widespread applications have gained ever-increasing interest in the last decade, which expresses their efficiency in practice. Accordingly, this review covers the current status of biomimetic complexes-graphene composites with particular emphasis on significant signs of their synthesis and characterization also highlighted applications of these composites in academia and industrial redox processes such as oxidation of organic compounds, epoxidation, oxygen reduction reactions, CO₂ reduction, and hydrogen evolution reactions.     

CuO nanoparticles supported on three‐dimensional nitrogen‐doped graphene as a promising catalyst for thermal decomposition of ammonium perchlorate

In the present work, CuO nanoparticles grown on three‐dimensional nitrogen‐doped graphene‐based frameworks (CuO@3D‐(N)GFs) were synthesized using a two‐step method. After the synthesis of three‐dimensional nitrogen‐doped graphene, CuO nanoparticles were deposited on it, by adding cupric acetate followed by thermal treatment. Different analysis methods were used to characterize the products. The as‐prepared nanocomposite was used as a promising catalyst for thermal decomposition of ammonium perchlorate (AP) as one of the most common oxidizer in composite propellants. Differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) techniques were used to investigate the thermal decomposition of ammonium perchlorate. According to the DSC/TGA, high temperature decomposition of AP decreased to 111 °C in the presence of 4% CuO@3D‐(N)GFs and the total heat release (ΔH) from decomposition of AP increased to 1893 J g^?1 which is much more than 590 J g^?1 for pure AP.     

Silica-Gel–Catalyzed Conversion of Stabilized Phosphorus Ylides to Benzo[e][1,3]Thiazocin Derivatives

The reaction between triphenylphosphine, dialkylacetylenedicarboxylates, and N-benzoyl thiourea derivatives leads to intermediates such as vinyltriphenylphosphonium salts, which undergo Michael addition to produce the highly functionalized phosphorus ylides containing alkyl groups in excellent yields. Using silica gel as a catalyst, the conversion of the stabilized phosphorus ylides to benzo[e][1,3]thiazocin derivatives in solvent free conditions at 90°C in fairly high yields is achieved.