Based on MFe2O4 (M=Co,Cu, and Ni): Magnetically recoverable nanocatalysts in synthesis of heterocyclic structural scaffolds

Abstract

Catalysis research under magnetically recoverable nanocatalysts is a well-known topic in organic synthesis. In recent times, catalysis research has clearly experienced a renaissance in the area of utility of ferrite nanoparticles based on their ability to recovery and reusability. In this review, the focus is on the fabrication, characterization and of application the MFe₂O₄ (M=Co, Cu, and Ni) nanocatalysts in synthesis of heterocyclic structural scaffolds.     

金纳米微粒作探针共振瑞利散射光谱法测定亚甲蓝

在pH为6.5~9.5的中性或弱碱性介质中, 金纳米微粒可与亚甲蓝(MB)阳离子靠静电引力及疏水作用力结合, 形成粒径较大的聚集体(平均粒径从12 nm增至20 nm), 这种聚集体的形成导致共振瑞利散射(RRS)强度显著增强, 最大散射峰位于371 nm. 在适当条件下, 散射强度(ΔI)与亚甲蓝浓度成正比. 该法具有高灵敏度, 将金纳米微粒作为测定亚甲蓝的高灵敏RRS探针, 对亚甲蓝的检出限为21.17 ng/mL, 该法简便， 快速， 且有较好的选择性, 可用于血液中亚甲蓝的测定.     

痕量Au Bi和Cd的萃取浮选及原子吸收光谱法测定

浮选法分离痕量金属离子,由于灵敏度高、选择性强已得到广泛应用。本文利用浮选法使Au~(3 )、Bi~(3 )和Cd~(2 )同KBr反应生成的络合阴离子与碱性染料罗丹明B(RB)生成既疏水又疏有机溶剂的三元离子缔合物,后者经甲苯浮选分出,用二甲基甲酰胺(DMF)溶解后,可用原子吸收法测定Au、Bi和Cd的含量。本方法用于海水,锌片和矿样中上述三种元素的微量测定,可提高检测灵敏度,而且K、Na、Ca、Mg等共存离子不生干扰。具体实验方法如下:     

Metal‐Xenon Complexes

Long after the first isolation of a xenon compound in 1962 the first compounds with metal‐xenon bonds are prepared. The metal atoms are so far Au and Hg. The most stable metal xenon compounds decompose under loss of xenon slightly above room temperature. They can only exist if solvents and counter ions are weaker bases than atomic xenon. Solvents and counter ions used so far are HF, (SbF₆)^—, and (Sb₂F₁₁)^—.     

Preparation,stability and two-dimensional ordered arrangement of gold nanoparticles capped by surfactants with different chain lengths

Gold nanoparticles modified with C10NH2, C12NH2, C16NH2 and C18NH2 respectively have been prepared by the reverse micelle method. Nanoparticles stability and their two-dimensional (2D) ordered arrangement were studied by UV-Vis absorption spectra and LB technique. The factors, such as the chain length and the size distribution of particles, which affect the 2D ordered arrangement formation, are discussed. Experimental results show that the longer the chain length of surfactants capping the gold nanoparticles, the more stable the nanoparticles, and the more ordered 2D arrangement of gold nanoparticles.     

高能Zn离子注入CaF2基质形成ZnO纳米粒子的机制、构型及电子结构

将高能Zn2+注入到CaF2介电基质中,在CaF2的表面下注入Zn2+浓度呈近似高斯分布,通过氧气氛后经热退火形成ZnO量子点.采用MaterialsStudio和Gaussian98W程序,结合实验结果计算分析了CaF2基质中ZnO纳米粒子的电子结构和光学性质.选取由4个ZnO原胞组成的超晶胞模型计算了ZnO纳米粒子的吸收光谱,理论结果与实验结果相符.对ZnO纳米粒子电子结构的研究结果表明,ZnO纳米粒子与CaF2基质的相互作用主要是ZnO表面的O与基质中Ca之间的作用,这种作用使ZnO纳米晶体的Fermi能级变窄,带隙相应减小;ZnO纳米粒子表面构型的变化对其本征吸收光谱没有影响,理论计算结果与实验值一致.     

Determination of gold in natural waters by neutron activation and γ-spectrometry after preconcentration with tributyl phosphate as solid extractant

A method for the preconcentration of gold in natural waters at the sampling site using tributyl phosphate as a solid extractant [Se(TBP)] was developed as a preliminary step prior to the determination of gold by neutron activation and γ-spectrometry. The SE(TBP) was saturated with gaseous chlorine for extracting all gold species. In batch experiments gold was quantitatively retained on the SE(TBP) in 10 min. After extraction and washing, the SE(TBP) was ashed or back-extracted. Gold was quantitatively eluted with hot, neutral 0.025 M thiourea. The gold content of residues of ashing or eluents after evaporation was determined by neutron activation and γ-spectrometry. The detection limit for the overall procedure was 0.2 ng 1^?1. The efficiency was tested on ‘equilibrated’ solutions prepared from river water and tracer solutions of gold. For comparison, the gold content of natural water samples was determined using preconcentration on activated charcoal.     

金橙G螯合形成树脂分离富集地质样品中的微量贵金属

主要研究了金橙Ｇ螯合形成树脂分离富集地质样品中金、铂、钯的最佳实验条件。在柱高大于１６ｃｍ，０．１ｍｏｌ／Ｌ ＨＣｌ介质的样品溶液以小于或等于０．５ｍＬ／ｍｉｎ流速过柱，用０．１ｍｏｌ／Ｌ ＨＣｌ的３％硫脲溶液以小于或等于０．５ｍＬ／ｍｉｎ流速洗脱金、铂、钯（和铑），都能同时定量富集。用火焰原子吸收光谱法测定，回收率均在９５％￣１１０％之间。经地质样品加标准回收实验，结果令人满意。证明这种以磺酸基     

How bridging ligands and neighbouring groups tune the gold-gold bond strength

Gold-gold interactions in small polynuclear complexes are analysed using extended Hückel calculations. They are influenced by the nature of the ligand donor atoms, by the bridging ligands, but most by the formal oxidation state of the metal. Au---Au bonds are much stronger in complexes of Au(II) and Au(III), but a weak interaction between two d¹⁰ centres exists for Au(I) complexes, owing to mixing of the s and p orbitals with the d orbitals. Phosphines induce stronger metal-metal bonds when coordinated trans to the Au---Au bond in [Au(II)[(CH₂)₂PPh₂]L]₂ (Ph = phenyl), but have the opposite effect when bonded orthogonally to the metal-metal axis in Au(I) binuclear species. When two gold atoms are bridged by a single carbon atom, belonging either to mesityl (Mes = 2,4,6-Me₃C₆H₂) or CR₂, the former produces stronger Au(I)---Au(I) interactions, reflected in shorter distances. Formal oxidation states are proposed for the gold atoms in two mixed-valence clusters, [Au4(C₆F₅)₂((PPh₃)_{2CH})2(PPh3)2](ClO4)2 and [{(2,4,6-C6F3H2)Au(CH2PPh2CH2)2Au{in2}-Au(CH₂PPh₂CH₂)₂Au](ClO₄)₂. The results suggest a higher oxidation state for the outer gold atoms, in both the T-shaped tetranuclear cluster and the Au₆ linear chain.     

Synthese und Struktur von [(Ph3PAu)3NPPh3][PF6]2, einem Gold(I)‐phosphoraniminato‐Komplex

Synthesis and Crystal Structure of [(Ph₃PAu)₃NPPh₃][PF₆]₂, a Gold(I) Phosphoraneiminato Complex The photolytic reaction of Ph₃PAuN₃ with Cr(CO)₆ in THF yields the phosphoraneiminato complex [(Ph₃PAu)₃NPPh₃]²⁺ in low yield as well as the cluster cation [(Ph₃PAu)₈]²⁺ as the main product. The phosphoraneiminato complex crystallizes from CH₂Cl₂ with [PF₆]^? ions as [(Ph₃PAu)₃NPPh₃][PF₆]₂·CH₂Cl₂ in the triclinic space group with a = 1200.8(1), b = 1495.6(2), 2053.5(5), α = 86.97(2)°, β = 82.79(1)°, γ = 81.87(2)°, and Z = 2. The phosphoraneiminato ligand bridges through its N atom three Au atoms, which itself are connected to each other by weak aurophilic interactions.