Nanoparticles@nanoscale metal-organic framework composites as highly efficient heterogeneous catalysts for size-and shape-selective reactions

Composites incorporating nanoparticles (NPs) within metal-organic frameworks (MOFs) find applications in many different fields.In particular,using MOF layers as molecular sieves built on the NPs could enable selectivity in heterogeneous catalysis.However,such composites typically exhibit low catalytic efficiency,due to the slow diffusion of the reactants in the long and narrow channels of the MOF shell.In order to improve the catalytic efficiency of these systems,here we report the fabrication of NPs incorporated in nanosized MOFs (NPs@nano-MOFs),obtained by reducing the size of the MOF crystals grown around the NPs.The crystal size of the composites was controlled by modulating the nucleation rate of the MOFs during the encapsulation of pre-synthesized and catalytically active NPs;in this way,NPs@MOF crystals smaller than 50 nm were synthesized and subsequently used as highly efficient catalysts.Due to the shorter path from the MOF surface to the active sites,the obtained Pt@nano-MOFs composites showed a higher conversion rate than their larger-sized counterparts in the synthesis of imines via cascade reaction of nitrobenzene and in the hydrogenation of olefins,while retaining the excellent size and shape selectivity associated with the molecular sieving effect of the MOF layer.The present strategy can also be applied to prepare other encapsulated nanostructures combining various types of NPs and nano-MOFs,thus highlighting the broad potential of this approach for developing optimized catalysts with high reactivity and selectivity.     

金属-有机络合聚合物(MOCPs)的研究进展

从配体的角度对中心离子与多齿配体间形成的稳定多孔金属-有机络合聚合物(MOCPs)的发展现状进行了综述.指出该材料自成为研究热点以来,各研究小组在对不同的构件分子进行组合构建新的MOCPs方面富有成效的工作,极大地丰富了络合聚合物的结构数据,但这种材料最引人注目的特性--孔及表面性质的可调控性及其对其各种应用特性,如分子识别、择形催化、择形吸附等所能带来的影响方面的研究还很不够.     

室温下金属有机骨架材料Cu3（BTC）2的合成与表征?

通过将配体均苯三甲酸 H 3 BTC 转化为均苯三甲酸钾,在室温条件下快速获得了金属有机骨架材料中的经典化合物 Cu3(BTC)2(HKUST-1),并通过SEM跟踪了晶体的生长过程。粉末 XRD 测试结果表明化合物为纯相,并具有较高结晶度,TGA 测试结果表明产物可稳定存在至300℃,N2吸附测试显示出产物具有高的比表面积及孔容积。研究工作为Cu3(BTC)2这一重要化合物提供了一条简便及低能耗的合成方法。     

阴离子功能化超微孔MOF高效选择性捕获低浓度CO2

CO2捕获,尤其低浓度CO2捕获,对人类在限域空间中长时间工作、降低天然气液化过程中CO2腐蚀及冻结效应极为重要.本文首次报道了一种具有一维孔道的ZU-16-Co(TIFSIX-3-Co)材料,该材料孔道中含大量电负性F原子,可实现400–10,000 ppm浓度下CO2的高效捕获.相比同构材料,孔径为3.62?的ZU...     

贵金属纳米粒子/金属有机骨架复合物的制备与应用进展

贵金属纳米粒子/金属有机骨架复合物因其在催化、传感、气体吸附与存储等诸多领域的应用前景而受到广泛关注.综述了贵金属纳米粒子/金属有机骨架复合物的制备方法及应用进展.对这类复合物的制备方法进行了归纳,并分析了其特点;总结了其在储氢、多相催化等领域的应用,以便更好地了解其应用前景.     

基于金属-有机骨架的锂离子电池硅负极的研究进展

近年来,金属-有机骨架(MOFs)及其衍生物由于具有高孔隙率、可修饰的官能团、可控的化学成分等优点,在改善硅负极体积膨胀和导电性等方面取得了很大进展.通过讨论MOFs及其衍生物在锂离子电池硅负极的最新研究成果,重点阐述了以MOFs为基体的硅负极的结构设计,提出了影响其电化学性能的相关因素.最后,针对MOFs及其衍生物在...     

Surfactant-assisted synthesis of lanthanide metal-organic framework nanorods and their fluorescence sensing of nitroaromatic explosives

Nanocrystals of [Eu₂(BDC)₃(H₂O)₂]_n (1), a lanthanide-containing metal-organic framework (MOF) with a two-dimensional layer structure, were synthesized by using a surfactant-assisted hydothermal method. Nanorods with different sizes were prepared in the presence of a cationic surfactant, cetyltrimethyl ammonium bromide, depending on various reaction times. To demonstrate the ability of 1 nanorods for detection of nitroaromatic explosives, the fluorescence quenching and fluorescence titration experiments were carried out. Fluorescence of 1 nanorods was found to be highly sensitive to the nitroaromatics such as 2-nitrotoluene, 4-nitrotoluene, 2,4-dinitrotoluene, and 2,6-dinitrotoluene, suggesting that lanthanide-containing MOF nanocrystals can be excellent candidates for the rapid detection of nitroaromatic explosives.     

Large array of sub-10-nm single-grain Au nanodots for use in nanotechnology

A uniform array of single-grain Au nanodots, as small as 5-8 nm, can be formed on silicon using e-beam lithography. The as-fabricated nanodots are amorphous, and thermal annealing converts them to pure Au single crystals covered with a thin SiO(2) layer. These findings are based on physical measurements, such as atomic force microscopy (AFM), atomic-resolution scanning transmission electron microscopy, and chemical techniques using energy dispersive X-ray spectroscopy. A self-assembled organic monolayer is grafted on the nanodots and characterized chemically with nanometric lateral resolution. The extended uniform array of nanodots is used as a new test-bed for molecular electronic devices.     

A novel route for the synthesis of indium nanoparticles in ionic liquid

In this paper, we report a novel preparation of indium nanoparticles by the reduction of indium chloride in ionic liquid by methanolic solution of NaBH₄. The particles are characterized by means of transmission electron microscopy (TEM), X-ray diffraction and UV-visible studies indicated that the powder consist of the cubic phase of indium. The particle size of indium nanoparticles is in the range of 20 nm mean diameter by Transmission electron microscopy (TEM). The samples display a strong surface plasma absorption band at 231 nm, which indicates that the sample is metal indium and the particle size is less than 20 nm. The thermal analysis of the sample indicate indium not indium oxide. Electrochemical studies show that indium nanoparticles have very good electrical properties.     

晶种和晶化模式对金属有机骨架MIL-101合成的影响

采用晶种导向法、静态水热晶化法和动态水热晶化法合成金属有机骨架MIL-101,通过XRD、SEM、N2物理吸附等表征方法考察了晶种和晶化模式对MIL-101产物收率和晶粒尺寸的影响。结果表明,MIL-101原粉作为晶种在合成过程中可溶解成(或解离成)适当的结构单元作为晶体生长核心,缩短晶化诱导期,提高产物收率。晶化模式影响MIL-101产物的收率和晶粒尺寸。动态晶化合成的MIL-101产物收率较静态晶化产物收率高,搅拌速率小于200r/min时收率随搅拌速率增加而增加。动态晶化合成的MIL-101产物晶粒尺寸较静态晶化产物晶粒尺寸小,随搅拌速率增加而减小。     

Gelothermal Synthesis of Monodisperse MIL-88A Nanoparticles with Tunable Sizes and Metal Centers for Potential Bioapplications

Developing novel synthetic strategies to downsize metal-organic frameworks (MOFs) from polydisperse crystals to monodisperse nanoparticles is of great importance for their potential bioapplications. In this work, a novel synthetic strategy termed gelothermal synthesis is proposed, in which coordination polymer gel is first prepared and followed by a thermal reaction to give the monodisperse MOF nanoparticles. This novel synthetic strategy successfully leads to the isolation of Materials of Institute Lavoisier (MIL-88), Cu(II)-fumarate MOFs (CufumDMF), and Zeolitic Imidazolate Frameworks (ZIF-8) nanoparticles. Focused on MIL-88A, the studies reveal that the size can be well-tuned from nanoscale to microscale without significant changes in polydispersity index (PDI) even in the case of in situ metal substitution. A possible mechanism is consequently proposed based on extensive studies on the gelothermal condition including sol-gel chemistry, thermal condition, kinds of solvents, and so on. The unique advantages of monodisperse MIL-88A nanoparticles over polydisperse ones are further demonstrated in terms of in vitro magnetic resonance imaging (MRI), cellular uptake, and drug-carrying properties.     

Ultra-Highly Active Ni-Doped MOF-5 Heterogeneous Catalysts for Ethylene Dimerization

Here, an ultra-highly active Ni-MOF-5 catalyst with high Ni loading for ethylene dimerization is reported. The Ni-MOF-5 catalysts are synthesized by a facile one-pot co-precipitation method at room temperature, where Ni²⁺ replaces Zn²⁺ in MOF-5. Unlike Zn²⁺ with tetrahedral coordination in MOF-5, Ni²⁺ is coordinated with extra solvent molecules except for four-oxygen from the framework. After removing coordinated solvent molecules, Ni-MOF-5 achieves an ethylene turnover frequency of 352 000 h⁻¹, corresponding to 9040 g of product per gram of catalyst per hour, at 35 °C and 50 bar, far exceeding the activities of all reported heterogeneous catalysts. The high Ni loading and full exposure structure account for the excellent catalytic performance. Isotope labeling experiments reveal that the catalytic process follows the Cossee–Arlman mechanism, rationalizing the high activity and selectivity of the catalyst. These results demonstrate that Ni-MOF-5 catalysts are very promising for industrial catalytic ethylene dimerization.     

Highly concentrated solvothermal synthesis of sub-10-nm BaTiO3 nanoparticles for optical applications

Single-crystalline barium titanate: BaTiO₃ (BT) nanoparticles (NPs) with sub-10-nm size have been successfully obtained by a highly concentrated solvothermal synthesis using a high concentration of Ba(OH)₂ and a titanium complex. To obtain sub-10-nm NPs, we focused on the gradual increase in the OH^– ion concentration and the decrease in the dielectric constant of solvents, and BT NPs were produced in 1 h even at a low temperature of 200 °C. High-resolution transmission electron microscopy (HR-TEM) observation revealed that the resulting BT NPs were single-nanometer size, consisting of a single-crystalline structure. ¹H-nuclear magnetic resonance (NMR) relaxation time (T₂) and zeta potential measurements demonstrated that our BT NPs had high dispersibility and dispersion stability under acidic conditions. The yellowness index measurements revealed that the BT NPs dispersions exhibited colorless property. The resulting single nanometer-sized BT NPs are promising as high refractive index materials for optical applications due to being dispersed in optical resins.     

Hydroformylation of alkenes over rhodium supported on the metal-organic framework ZIF-8

A highly porous and crystalline metal-organic framework （MOF） ZIF-8 has been synthesized and used for the preparation of a supported rhodium nanoparticle catalyst （Rh@ZIF-8）. The material has been characterized by PXRD, TEM, EDX, ICP-AES and nitrogen adsorption. The catalytic properties of Rh@ZIF-8 have been investigated in the hydroformylation of alkenes, with different chain length and structure, to give the corresponding aldehydes, and showed high activity. Furthermore, after the reaction was complete, the catalyst could be easily separated from the products by simple decantation and reused five times without a significant decrease in the activity under the investigated conditions.     

Engineering Dynamic Defect of CeIII/CeIV-Based Metal-Organic Framework through Ultrasound-Triggered Au Electron Trapper for Sonodynamic Therapy of Osteomyelitis

Defect engineering is an important way to tune the catalytic properties of metal-organic framework (MOF), yet precise control of defects is difficult to achieve. Herein, a cerium-based MOF (CeTCPP) is decorated with Au nanoparticles. Under ultrasound irradiation, Au nanoparticles can precisely turn 1/3 of the pristine Ce³⁺ nodes into Ce⁴⁺. With the stable existence of Ce⁴⁺, the coordination of Ce nodes changed, causing the structural irregularity in CeTCPP-Au, so that the electron-hole recombination is obviously hindered, facilitating the generation of reactive oxygen species. Therefore, under 20 min of ultrasound irradiation, the CeTCPP-Au showed superior antibacterial efficacy of over 99% against Staphylococcus aureus and Escherichia coli with good biocompatibility, which is further used for effective therapy of osteomyelitis. Overall, this work provides a dynamic defect formation strategy of MOF through the electron trapping of Au nanoparticles, which also sheds light on sonodynamic therapy in curing deep-seated lesions.     

Customizing Metal-Organic Frameworks by Lego-Brick Strategy for One-Step Purification of Ethylene from a Quaternary Gas Mixture

One-step purification of ethylene (C₂H₄) from a quaternary gas mixture of C₂H₆/C₂H₄/C₂H₂/CO₂ by adsorption is a promising separation process, yet developing adsorbents that synergistically capture various gas impurities remains challenging. Herein, a Lego-brick strategy is proposed to customize pore chemistry in a unified framework material. The ethane-selective MOF platform is further modified with customized binding sites to specifically adsorb acetylene and carbon dioxide, thus one-step purification of C₂H₄ with high productivity of polymer-grade product (134 mol kg⁻¹) is achieved on the assembly of porous coordination polymer-2,5-furandicarboxylic acid (PCP-FDCA) and PCP-5-aminoisophthalic acid (IPA-NH₂). Computational studies verify that the low-polarity surface of this MOFs-based platform provides a delicate environment for C₂H₆ recognition, and the specific binding sites (FDCA and IPA-NH₂) exhibit favorable trapping of C₂H₂ and CO₂ via C H^δ+···O^δ− and C^δ+···N^δ− electrostatic interactions, respectively. The proposed Lego-brick strategy to customize binding sites within the MOFs structure provides new ideas for the design of adsorbents for compounded separation tasks.     

金属有机骨架材料在气体吸附与分离中的应用研究进展

金属有机骨架材料(MOFs)因具有超高比表面积、较大的孔隙率、多样化且可调的孔道结构及相对温和的制备条件等优势,目前已成为化学和材料等学科的研究热点之一。概述了MOFs材料的制备方法及其用于气体(含碳、含氮及含硫)吸附与分离方面的研究进展,并对其在该方面今后的发展趋势和应用前景进行了展望。     

镧系金属有机骨架/聚酰亚胺复合材料的制备及其性能

采用水热法合成两种含镧系稀土金属的金属有机骨架：1,3,5-均苯三甲酸铽（Tb （BTC））和1,3,5-均苯三甲酸铕（Eu （BTC））,采用原位法以1,4-双（2-三氟甲基-4-氨基苯氧基）苯（6FAPB）和1,2,3,4-环丁烷四酸二酐（CBDA）为单体,将Tb （BTC）和Eu （BTC）分别引入到聚酰亚胺（PI）中,制备出Tb （BTC）和Eu （BTC）质量分数分别为7wt%的Tb （BTC）/PI和Eu （BTC）/PI两种复合材料膜。利用FTIR、紫外-可见光谱仪（UV-vis）、TGA、XRD、SEM、万能拉伸试验机和气体渗透性测试等对Tb （BTC）/PI和Eu （BTC）/PI复合材料的结构和性能进行表征。研究结果表明,Tb （BTC）和Eu （BTC）含有较少的孔结构,且孔径在介孔范围,但热稳定性较高。Tb （BTC）和Eu （BTC）的加入提高了Tb （BTC）/PI和Eu （BTC）/PI复合材料的热性能和力学性能,玻璃化转变温度由纯PI （6FAPB-CBDA）的351.9℃分别提高到358.0℃和354.8℃,失重5%热分解温度由431.6℃分别提高到447.8℃和441.1℃,拉伸强度由60.8 MPa分别提高到77.7 MPa和70.4 MPa,杨氏模量由1.54 GPa分别提高到2.80 GPa和2.17 GPa。但Tb （BTC）/PI和Eu （BTC）/PI复合材料膜的光透明性有所降低,500 nm处的光透过率由82.3%分别下降到23.0%和24.2%。气体渗透测试结果表明,Tb （BTC）和Eu （BTC）的加入均可提高PI （6FAPB-CBDA）膜的气体渗透性,Eu （TBC）/PI对H₂、O₂、N₂和CO₂的渗透性较高,分别为119.23、15.02、3.21和90.35 Barrer,O₂/N₂为4.68,CO₂/N₂为28.15。