Synthesis of Boron–Nitrogen–Phosphorus Compounds from N-Silylphosphoranimines

Two modes of reactivity of N-silylphosphoranimines have been utilized to prepare the title compounds containing either B–N=P or Si–N=P–N–B linkages. First, silicon-nitrogen bond cleavage reactions of the N-silylphosphoranimines, Me₃SiN=PMe(R)OCH₂CF₃ (1: R=Me, 2: R=Ph), with various chloroboranes gave the new N-borylphosphoranimines, Ph(Me₂N)B–N=PMe₂OCH₂CF₃ (2) and [(Me₃Si)₂N](Cl)B–N=PMe₂OCH₂CF₃ (10). In other cases, however, the expected B–N=P products were unstable and cyclic phosphazenes [Me(R)P=N]_3,4 were obtained. Second, deprotonation-substitution reactions of the aminophosphoranimines, Me₃SiN=P(R)Me–N(R)H, were used to prepare a series of novel (borylamino)-phosphoranimines, Me₃SiN=P(R)(Me)–N(R)–B(NMe₂)₂ (18: R=Me, R=t-Bu; 19: R=R=Me; 20: R=Ph, R=t-Bu; 21: R=Ph, R=Me) and Me₃SiN=PMe₂–N(t-Bu)–B(Ph)X (22: X=NMe₂, 23: X=OCH₂CF₃). All of the new boron–nitrogen–phosphorus products were fully characterized by multinuclear NMR (¹H, ¹³C, and ³¹P) spectroscopy and elemental analysis.     

All-Optical Switching between Optical Bistability and Multistability via Exciton Spin Relaxation

All-optical coherent control of optical bistability(OB) and optical multistability(OM) in the 4.8 nm Zn Se single-quantum well based on excitons and biexciton transitions is investigated. By applying a pair of phase-locked laser pulses all-optical coherent control can be obtained. Theoretical analysis with density matrix and Maxwell equations then yield the optical bistability and optical multistability. It is shown that by controlling the coherent and incoherent processes, the intensity threshold of OB and OM can be modified. Also, it is found that the switching between OB and OM or vice versa can be occurred for some controllable parameters.     

Uniform copper nanoparticles as an inexpensive and efficient catalyst for synthesis of novel β-carbonyl-1, 2, 3-triazoles in water medium

Copper nanoparticles as an efficient, inexpensive catalyst were prepared via ball milling for synthesis of β-carbonyl 1, 2, 3-triazoles from azido alcohol by click reaction in water. An extensive range of raw materials such as sodium azide, phenacyl bromide, epichlorohydrin, and terminal alkynes were used. Complete reduction of CuO in presence of NaBH₄ was done via ball milling with a ball-to-powder weight ratio of 50:1 under air atmosphere at room temperature. The final copper nanoparticles (Cu NPs) were characterized by SEM, EDX, XRD and FT-IR. The Cu NPs catalyzed one-pot three component synthesis of β-carbonyl 1, 2, 3-triazoles at room temperature with short reaction time and high product yields. The catalyst could be easily recovered and reused in several successive runs.

     

High-temperature hydrogen production by solar thermochemical reactors,metal interfaces,and nanofluid cooling

Journal of Thermal Analysis and Calorimetry - Solar thermochemical reactors have been considered in recent studies because of converting the solar energy to a fuel, which is called solar fuel. In...     

Influence of Fe/Ba ratio,basic agent and calcination temperature on the physical properties of nanocrystalline barium hexaferrite thin films prepared by a sol–gel method

In this work nanocrystalline BaFe₁₂O₁₉ thin films have been prepared on the Si (1 1 0) substrates by a sol–gel method using the aqueous solution of metal nitrates. The efforts have been done to decrease the calcination temperature and to reduce the crystallite size of the single-phase barium ferrite thin films. The precursor solutions were primed with the various Fe/Ba ratios and two kinds of the basic agents, and the coated films were heat treated at the different temperatures. The thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The effects of calcination temperature, molar ratio of Fe/Ba and basic agent on composition, crystallites size and morphology were also investigated.     

新型吡咯烷键合反相高效液相色谱固定相的制备与研究（英文）

正A new ionic liquid-based high-performance liquid chromatography stationary phase is reported.A derivative of N-methyl pyrrolidinium tetrafluoroborate was covalently immobilized on the surface of silica particles to prepare silica-based N-methyl pyrrolidinium tetrafluoroborate(SilprMP BF4)stationary phase.The obtained ionic liquid-modified silica was evaluated and confirmed by elemental analysis,infrared spectroscopy,and thermogravimetric analysis.A column was packed with the modified particles.The retention behavior of aromatic compounds,alkyl benzenes,and acidic and basic compounds on the SilprMP BF4 stationary phase was studied under reversed-phase liquid chromatography conditions.The effect of the eluent pH on the separation of the acidic and basic compounds was also studied.The new stationary phase involves multiple retention mechanisms,such as electrostatic,hydrophobic,ion-dipole,and anion-exchange interactions,which might lead to multipurpose separation media.     

Synthesis,spectroscopic and X-ray structural studies of mercury(II) halide complexes of 4-methoxybenzoylmethylenetriphenylphosphorane

The reactions of the title ylide {(C₆H₅)₃PCHCOC₆H₄OCH₃)} (MBPPY) with mercury(II) chloride and mercury(II) bromide in equimolar ratios using methanol as the solvent produces crystals of [(MBPPY) · HgCl₂]₂ (1) and [(MBPPY) · HgBr₂]₂ (2), respectively. Single crystal X-ray analyses reveal the presence of centrosymmetric dimeric structures containing the ylide and HgX₂ (X = Cl or Br) in both cases. The IR and NMR data of the product [(MBPPY) · HgI₂]₂ (3), formed by the reaction of mercury(II) iodide with the same ylide, are similar to those of 1 and 2. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products.     

Dispersive Liquid‐Liquid Microextraction of Cu(II) Using a Novel Dioxime for Its Highly Sensitive Determination by Graphite Furnace Atomic Absorption Spectrometry

A dispersive liquid‐liquid microextraction (DLLME) technique was proposed for the enrichment and graphite furnace atomic absorption spectrometric (GFAAS) determination of Cu²⁺ in water samples. In this method a mixture of 480 μL acetone (disperser solvent) containing 26 μg S,S‐bis(2‐aminobenzyl)‐dithioglyoxime (BAT) ligand and 20 μL carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5 mL aqueous sample containing copper ions (analyte). Thereby, a cloudy solution formed. After centrifugation, the fine droplets containing the extracted copper complex were sedimented at the bottom of the conical test tube. This phase was collected by a microsyring and after dilution by methanol, 20 μL of it was injected into the graphite tube of the instrument for analysis. Effects of some parameters on the extraction, such as extraction and disperser solvent type and volume, extraction time, salt concentration, pH and concentration of the chelating agent were optimized. The response surface method was used for optimization of the effective parameters on the extraction recovery. Under these conditions, an enrichment factor of 312 was obtained. The calibration graph was linear in the rage of 2–50 μ L⁻¹ Cu²⁺ with a detection limit of 0.03 μg L⁻¹ and a relative standard deviation (RSD) for five replicate measurements of 3.4% at 20 μg L⁻¹ Cu²⁺. The method was successfully applied to the determination of Cu²⁺ in some spring water samples.     

In situ monitoring of pH titration by Raman spectroscopy

Molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman technique was chosen because it allows the identification of compounds in different states, and it can give information about the molecular geometry from the analysis of the vibrational spectra. The effect of pH on organic compounds can give information about the ionisation of molecule species. In this study the ionisation steps of salicylic acid and paracetamol have been studied by means of potentiometry coupled with Raman spectroscopy at 30.0 °C in a solution of ionic strength 0.96 mol dm^?3 (KNO₃) and 0.04 mol dm^?3 (HNO₃). The protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the three different species in the Raman spectra of aqueous salicylic acid have been identified satisfactorily, characterised, and determined by numeric treatment of the data using a multiwavelength curve-fitting program and confirmed with the observed spectral information.