高选择性和稳定性的CsPW/Nb2O5催化剂用于甘油脱水制备丙烯醛（英文）

以磷钨酸铯盐Cs2.5H0.5PW12O40(CsPW)为活性组分,负载到Nb2O5载体上,并用于甘油脱水制备丙烯醛的反应中.通过调节焙烧温度(400–700°C)以及活性组分负载量(5儃60 wt%),对催化剂酸性进行调节.CsPW负载量为20 wt%,500°C焙烧的CsPW/Nb2O5催化剂性能最佳,甘油转化率为96%,丙烯醛选择性为80%,反应10 h内没有失活现象,并且该催化剂具有良好的热稳定性,可通过烧炭进行再生.     

Synthesis and reactivity of new mono- and dinuclear niobium and tantalum imido complexes: X-ray crystal structure of [Ta(η-C5H4SiMe3)Cl2{NC6Me4-4-(N(SiMe3)2)}]

The reaction of [1,4-{SiMe₃(H)N}₂C₆Me₄] (1) with 2 equivalents of LiBuⁿ followed by the addition of SiMe₃Cl gave the diamine compound [1,4-{(SiMe₃)₂N}₂C₆Me₄] (2). [Ta(η⁵-C₅H₄SiMe₃)Cl₄] reacts with 2, in a 2:1 stoichiometric ratio, to initially yield a mixture of the dinuclear, [{Ta(η⁵-C₅H₄SiMe₃)Cl₂}₂(μ-1,4-NC₆Me₄N)] (3), and mononuclear, [Ta(η⁵-C₅H₄SiMe₃)Cl₂{NC₆Me₄-4-(N(SiMe₃)₂)}] (4), imido complexes. 3 can be obtained exclusively by submitting the reaction mixture to repeated cycles of evacuation, to remove volatiles, followed by addition of solvent and subsequent heating. The mononuclear imido complex 4 was isolated from the reaction of [Ta(η⁵-C₅H₄SiMe₃)Cl₄] with 2 in a 1:1 stoichiometric ratio. The molecular structure of 4 was determined by X-ray diffraction studies. [TaCl₃(CH₃CN)₂{NC₆Me₄-4-(N(SiMe₃)₂)}] (5) has been prepared by the reaction of one molar equivalent of TaCl₅ with 2 in a CH₃CN/CH₂Cl₂ solvent mixture. The synthesis of the niobium complexes, [{Nb(η⁵-C₅H₄SiMe₃)Cl₂}₂(μ-1,4-NC₆Me₄N)] (6) and [Nb(η⁵-C₅H₄SiMe₃)Cl₂{NC₆Me₄-4-(N(SiMe₃)₂)}] (7), was achieved in a similar manner to their tantalum analogues. The reactivity of 7 towards nucleophilic reagents, namely lithium benzamidinate, lithium (trimethylsilyl)cyclopentadienyl or lithium dimethylamide, has been studied and the following compounds prepared:[Nb(η⁵-C₅H₄SiMe₃)RCl{NC₆Me₄-4-(N(SiMe₃)₂)}] (R = η⁵-C₅H₄SiMe₃ (8), PhC(NSiMe₃)₂ (9), NMe₂ (10)). In an attempt to form the hetero bimetallic complex, [{Nb(η⁵-C₅H₄SiMe₃)Cl₂}(μ-1,4-NC₆Me₄N){Ta(η⁵-C₅H₄SiMe₃)Cl₂}] (11), the reaction of 7 with [Ta(η⁵-C₅H₄SiMe₃)Cl₄] has been studied. Analysis of the reaction products showed that 11 may exist in equilibrium with the homo bimetallic complexes 3 and 6.     

Hydrophilic Nb-immobilized magnetic core–shell microsphere – A novel immobilized metal ion affinity chromatography material for highly selective enrichment of phosphopeptides

Rapid and selective enrichment of phosphopeptides from complex biological samples is essential and challenging in phosphorylated proteomics. In this work, for the first time, niobium ions were directly immobilized on the surface of polydopamine-coated magnetic microspheres through a facile and effective synthetic route. The Fe₃O₄@polydopamine-Nb⁵⁺ (denoted as Fe₃O₄@PD-Nb⁵⁺) microspheres possess merits of high hydrophilicity and good biological compatibility, and demonstrated low limit of detection (2 fmol). The selectivity was also basically satisfactory (β-casein:BSA = 1:500) to capture phosphopeptides. They were also successfully applied for enrichment of phosphopeptides from real biological samples such as human serum and nonfat milk. Compared with Fe₃O₄@PD-Ti⁴⁺ microspheres, the Fe₃O₄@PD-Nb⁵⁺ microspheres exhibit superior selectivity to multi-phosphorylated peptides, and thus may be complementary to the conventional IMAC materials.     

直流电弧原子发射光谱法测定铌、钽中硅含量

通过直流电弧原子发射光谱仪,配备固体多道光学检测器-电感耦合器件,建立了直流电弧原子发射光谱法测定铌、钽中硅含量的方法。硅的分析线为288.160 nm,铌中硅的缓冲剂为碳粉和氯化银,钽中硅的缓冲剂为碳粉。硅的质量分数在0.001%~0.100%范围内与其光谱强度呈线性关系,相关系数均在0.999 6以上。加标回收率在97.7%~103%之间,测定值的相对标准偏差(n=7)均小于8%。     

A Novel Amperometric Transducer Electrode with Iridium‐Niobium Binary Alloys

We have discovered that an Ir‐23Nb binary alloy more effectively oxidizes hydrogen peroxide than Ir, Ir‐13Nb, Ir‐17Nb, Ir‐30Nb, Ir‐43Nb, Ir‐62Nb, or Nb. The oxidation capability was determined via cyclic voltammogram measurements of pH‐buffer and hydrogen peroxide. We ascertained that applying a 0.7 V potential produces hydrogen peroxide currents of 9.2 μA/mm² Ir‐23Nb, 5.3 μA/mm² Ir, 5.1 μA/mm² Ir‐17Nb, 3.7 μA/mm² Ir‐13Nb, 2.0 μA/mm² Ir‐30Nb, 1.5 μA/mm² Ir‐43Nb, 0.6 μA/mm² Ir‐62Nb, and 0.13 μA/mm² Nb. These results indicate that the effective oxidation of Ir‐23Nb for hydrogen peroxide might be due to its fcc+L1₂ two‐phase structure and that Ir‐23Nb can be used as an amperometric transducer material.     

Kalman滤波-流动注射化学发光法同时测定痕量铌和钽的研究

流动注射化学发光（Flow injection-chemiluminescence,简称FI-CL）是基于流动注射（FI）进样技术与化学发光（CL）定量分析结合的痕量分析技术,具有仪器简单、操作方便及易于自动化等特点,从而在分析痕量元素方面取得了较大进展,尤其在痕量金属元素快速分析方面更具有优势.     

Synthesis and Structure of [NbCl3(NPPh2Fc)2]: The First Example of a Complex Containing a Redox‐functionalised Phosphaneiminato Ligand

Reaction of Me₃SiNPPh₂Fc (Fc = ferrocenyl) with niobium pentachloride affords [NbCl₃(NPPh₂Fc)₂], whose redox‐functionalised phosphaneiminato ligands exhibit remarkably different bend angles at nitrogen according to a crystal structure analysis.     

New Hexanuclear Niobium Cluster Compounds with Perfluorinated Ligands Made Using Ionic Liquids

Three new hexanuclear niobium cluster compounds, which carry trifluoroacetate ligands on the exo sites of the metal atom octahedra, were synthesized and characterized. For the syntheses, the ionic liquid 1,1,3,3‐tetramethylguanidinium‐trifluoroacetat, (TMG‐H)TFA, was used as solvent as well as source for the ligands and cations. All three cluster compounds consist of the [Nb₆Cl₁₂(TFA)₆]^4– anion and (TMG‐H)⁺, (TMG‐H)⁺ + (TMGTFAA‐H)⁺, or (TMGTFAA‐H)⁺ cations [(TMGTFAA‐H)⁺ = 1,1,3,3‐tetramethylguanidine‐trifluoroacetamidinium]. TMGTFAA and the corresponding cation are obtained by either heating and/or by addition of TFA‐anhydrate to (TMG‐H)TFA in a slow chemical reaction. (TMGTFAA‐H)TFA comprises a second ionic liquid in this reaction system, which provides cations for two of the three characterized niobium cluster compounds. Structural details of the three new cluster compounds as well as of TMGTFAA were obtained by X‐ray diffraction experiments. With a melting point of approx. 145 °C the cluster compound with the (TMG‐H)⁺ cations almost can be called a “cluster ionic liquid“.