Synthesis,Crystal Structure and Characterization of a Ni(Ⅱ) Complex of Constructed 2,6-Bis(benzimidazol-2-yl) pyridine

A fluorescent Ni(II) complex 1, [Ni(OH-H2Bdc)(Bibimp)]n·nH2O, constructed with 5-hydroxyisophthalic acid(OH-H2Bdc) and 2,6-bis(2-benzimidazolyl)pyridine)(Bibimp) has been synthesized by hydrothermal methods and structurally characterized by elemental analysis, IR spectroscopy, TG/DTG, fluorescence spectrum and single-crystal X-ray diffraction. The title complex crystallizes in triclinic system, space group P1 with a = 10.187(2), b = 10.273(2), c = 13.401(3), α = 69.65(3), β = 69.66(3), γ = 70.61(3)o, V = 1196.8(4) 3, and Z = 2. The adjacent chains of complex 1 are stacked offset with respect to each other in an ABAB fashion by van der Waals interactions, and only a weak interlayer nonclassical C–H···O hydrogen bond has been observed. Complex 1 displays strong blue fluorescent emissions at 483 nm in the solid state upon photo-excitation at 365 nm at room temperature.     

Synthesis,Crystal Structure and Photoluminescence of a Three-coordinate Ag(Ⅰ) Complex

A three-coordinate Ag(I) complex, [Ag(Mepzpy)(PAr3)]BF4·H2O(1, Mepzpy = 3-methyl-1-(2-pyridyl)pyrazole, PAr3 = tri(o-tolyl)phosphine), was synthesized from the reaction of Ag(CH3CN)4BF4, PAr3 and Mepzpy in CH3 CN at room temperature. The compound was characterized by UV-vis, NMR and X-ray single-crystal structure analysis. It crystallizes in triclinic space group P1 with a = 10.2251(5), b = 10.6014(5), c = 15.7012(5) , α = 92.963(3), β = 92.641(3), γ = 114.647(4)o, V = 1540.6(1) 3, Z = 2, Mr = 676.24, Dc = 1.458 g/cm3, F(000) = 688, μ = 6.187 mm-1, GOOF = 1.038, the final R = 0.0530 and w R = 0.1493 for 6371 observed reflections with I 2σ(I). Compound 1 is ionic. It is composed of a BF4- anion and a [Ag(Mepzpy)(PAr3)]+ cation. The Ag(I) ion adopts a distorted trigonal pyramidal coordination geometry defined by two nitrogen atoms and a phosphorous atom. The complex emits blue luminescence with maximum peaks at 470 nm in solid state at room temperature.     

火焰原子吸收法测定中药草珊瑚叶中五种金属元素的含量

目的运用火焰原子吸收光谱法测定中药草珊瑚叶中的Fe、Zn、Mg、Ca、Cu 5种金属元素的含量。方法用浓HNO3-HCl O4消解样品,采用标准曲线法测定其5种金属元素含量。结果所测的样品中含有丰富的人体必需微量元素。方法回收率在99.35%-103.30%之间,样品相对偏差小于5%。结论该法简单、准确,结果令人满意。     

基于磷钼酸和2-(2-羟基苯)苯并咪唑复合物的晶体结构和质子导电性(英文)

以磷钼酸和2-(2-羟基苯)苯并咪唑(L)为原料制备了具有质子导电性的有机-无机化合物[H3L2(PMo12O40)·7H2O·4CH3OH]n(1).单晶X射线衍射分析结果表明化合物1具有基于磷钼酸、2-(2-羟基苯)苯并咪唑及溶剂甲醇分子的二维氢键网络结构;质子导电性能测试结果表明该化合物在100℃、相对湿度为98%时的电导率达到10-4 S·cm-1.     

Formation of a Single-Crystal Aluminum-Based MOF Nanowire with Graphene Oxide Nanoscrolls as Structure-Directing Agents

An innovative strategy is proposed to synthesize single-crystal nanowires (NWs) of the Al³⁺ dicarboxylate MIL-69(Al) MOF by using graphene oxide nanoscrolls as structure-directing agents. MIL-69(Al) NWs with an average diameter of 70±20 nm and lengths up to 2 μm were found to preferentially grow along the [001] crystallographic direction. Advanced characterization methods (electron diffraction, TEM, STEM-HAADF, SEM, XPS) and molecular modeling revealed the mechanism of formation of MIL-69(Al) NWs involving size-confinement and templating effects. The formation of MIL-69(Al) seeds and the self-scroll of GO sheets followed by the anisotropic growth of MIL-69(Al) crystals are mediated by specific GO sheets/MOF interactions. This study delivers an unprecedented approach to control the design of 1D MOF nanostructures and superstructures.     

Single-Atom Iron Catalysts on Overhang-Eave Carbon Cages for High-Performance Oxygen Reduction Reaction

Single-atom catalysts have drawn great attention, especially in electrocatalysis. However, most of previous works focus on the enhanced catalytic properties via improving metal loading. Engineering morphologies of catalysts to facilitate mass transport through catalyst layers, thus increasing the utilization of each active site, is regarded as an appealing way for enhanced performance. Herein, we design an overhang-eave structure decorated with isolated single-atom iron sites via a silica-mediated MOF-templated approach for oxygen reduction reaction (ORR) catalysis. This catalyst demonstrates superior ORR performance in both alkaline and acidic electrolytes, comparable to the state-of-the-art Pt/C catalyst and superior to most precious-metal-free catalysts reported to date. This activity originates from its edge-rich structure, having more three-phase boundaries with enhanced mass transport of reactants to accessible single-atom iron sites (increasing the utilization of active sites), which verifies the practicability of such a synthetic approach.     

Porous Tantalum Nitride Single Crystal at Two-Centimeter Scale with Enhanced Photoelectrochemical Performance

Porous tantalum nitride (Ta₃N₅) single crystals, combining structural coherence and porous microstructure, would substantially improve the photoelectrochemical performance. The structural coherence would reduce the recombination of charge carriers and maintain excellent transport properties while the porous microstructure would not only reduce photon scattering but also facilitate surface reactions. Here, we grow bulk-porous Ta₃N₅ single crystals on a two-centimeter scale with (002), (023), and (041) facets, respectively, and show significantly enhanced photoelectrochemical performance. We show the preferential facet growth of porous crystals in a lattice reconstruction strategy in relation to lattice match and lattice channel. We present the facet engineering to enhance light absorption, exciton lifetime and transport properties. The porous Ta₃N₅ single crystal boosts photoelectrochemical oxidation of alcohols with the (002) facet showing the highest performance of >99 % alcohol conversion and >99 % aldehyde/ketone selectivity.     

Atomic-Scale Insight into Exsolution of CoFe Alloy Nanoparticles in La0.4Sr0.6Co0.2Fe0.7Mo0.1O3−δ with Efficient CO2 Electrolysis

In situ exsolution of metal nanoparticles in perovskite under reducing atmosphere is employed to generate a highly active metal–oxide interface for CO₂ electrolysis in a solid oxide electrolysis cell. Atomic-scale insight is provided into the exsolution of CoFe alloy nanoparticles in La_0.4Sr_0.6Co_0.2Fe_0.7Mo_0.1O_3−δ (LSCFM) by in situ scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy and DFT calculations. The doped Mo atoms occupy B sites of LSCFM, which increases the segregation energy of Co and Fe ions at B sites and improves the structural stability of LSCFM under a reducing atmosphere. In situ STEM measurements visualized sequential exsolution of Co and Fe ions, formation of CoFe alloy nanoparticles, and reversible exsolution and dissolution of CoFe alloy nanoparticles in LSCFM. The metal–oxide interface improves CO₂ adsorption and activation, showing a higher CO₂ electrolysis performance than the LSCFM counterparts.     

Stereospecific 1,2-Migrations of Boronate Complexes Induced by Electrophiles

The stereospecific 1,2-migration of boronate complexes is one of the most representative reactions in boron chemistry. This process has been used extensively to develop powerful methods for asymmetric synthesis, with applications spanning from pharmaceuticals to natural products. Typically, 1,2-migration of boronate complexes is driven by displacement of an α-leaving group, oxidation of an α-boryl radical, or electrophilic activation of an alkenyl boronate complex. The aim of this article is to summarize the recent advances in the rapidly expanding field of electrophile-induced stereospecific 1,2-migration of groups from boron to sp² and sp³ carbon centers. It will be shown that three different conceptual approaches can be utilized to enable the 1,2-migration of boronate complexes: stereospecific Zweifel-type reactions, catalytic conjunctive coupling reactions, and transition metal-free sp²–sp³ couplings. A discussion of the reaction scope, mechanistic insights, and synthetic applications of the work described is also presented.     

A Layered Cationic Aluminum Oxyhydroxide as a Highly Efficient and Selective Trap for Heavy Metal Oxyanions

Cationic framework materials, especially pure inorganic cationic frameworks that can efficiently and selectively capture harmful heavy metal oxyanions from aqueous solution are highly desired yet scarcely reported. Herein, we report the discovery of a 2D cationic aluminum oxyhydroxide, JU-111, which sets a new benchmark for heavy metal oxyanion sorbents, especially for Cr^VI. Its structure was solved based on 3D electron diffraction tomography data. JU-111 shows fast sorption kinetics (ca. 20 min), high capture capacity (105.4 mg g⁻¹), and broad working pH range (3–10) toward Cr^VI oxyanions. Unlike layered double hydroxides (LDHs), which are poorly selective in the presence of CO₃²⁻, JU-111 retains excellent selectivity for Cr^VI even under a large excess of CO₃²⁻. These superior features coupled with the ultra-low cost and environmentally benign nature make JU-111 a promising candidate for toxic metal oxyanion remediation as well as other potential applications.