Nanocage containing metal-organic framework constructed from a newly designed low symmetry tetra-pyrazole ligand

1368-Tetra(1H-pyrazol-4-yl)-9H-carbazole (H₄CTP), a tetra-pyrazole ligand with C_s symmetry, has been synthesized based on a carbazole core. A solvothermal reaction of this ligand with NiCl₂·6H₂O gave a three-dimensional (3-D) metal-organic framework (MOF), [Ni(H₄CTP)Cl₂]·nS (BUT-41), which crystallized in the cubic space group Pm-3 in spite of H₄CPT with a central carbazole core and four peripheral pyrazole rings has low symmetry. The framework of BUT-41 can be regarded as a four-connected 3-D net with the rhr topology when both the organic ligand and the metal center are considered as four-connected nodes. Nanocages with internal diameter of 2 nm are present in the framework of BUT-41, which are formed by interconnecting 12 H₄CTP ligands and 20 Ni(II) ions. Each nanocage connects with six adjacent cages through sharing hexagonal windows with diameter over 7 Å, resulting in 3-D intersecting channels of the MOF. Although the tetra-pyrazole ligand is not deprotonated after coordination with the metal ions, powder X-ray diffraction and N₂ adsorption experiments reveal that the framework of BUT-41 is rigid and permanently porous with the Brunauer-Emmett-Teller surface area up to 1551 m² g^?1. Furthermore, gas adsorption experiments show that this MOF selectively adsorbs CO₂ over N₂ and CH₄.     

Photo Catalytic Degradation of Azo Dyes over Mn2+ Doped TiO2 Catalyst under UV/Solar Light:An Insight to the Route of Electron Transfer in the Mixed Phase of Anatase and Rutile

Mn²⁺ ion was doped into the TiO₂ matrix and its photocatalytic activity was evaluated for the degradation of a mono azo dye methyl orange (MO) and a di‐azo dye brilliant yellow (BY) under UV/solar light. X‐ray diffraction results revealed the phase transformation from anatase to rutile due to the inclusion of Mn²⁺ ion into the TiO₂ matrix. All the doped catalysts showed a red shift in the band gap to the visible region. The degradation reaction of the dyes was found to be dependent on its structure. It was found that mono azo dye degrades faster than di azo dye under UV/solar light. The rate constant under identical conditions calculated for the degradation of MO is 2.4 times (under UV light) and 4.5 times (under solar light) higher compared to BY. Among the photocatalysts studied, Mn²⁺(0.06 at.%)‐TiO₂ showed higher activity under both UV and solar light illumination. The synergestic effect in the bicrystalline framework of anatase and rutile effectively suppresses the charge carrier recombination and enhances the photocatalytic activity. The degradation reaction was followed by UV‐visible spectroscopy and the photoproducts formed were analyzed by GC‐MS techniques.     

[Co(Phen)2(H2O)2](HL)NO3·3H2O的合成及晶体结构

在水溶液中,以邻菲咯啉、丁二酸与硝酸钴为原料合成了一个新的超分子化合物[Co(Phen)2(H2O)2].(HL).(NO3).3H2O,并经元素分析、IR、X射线单晶衍射分析进行了结构表征.结构分析表明,晶体属三斜晶系,P1-空间群,a=0.968 0(2)nm,b=1.370(3)nm,c=1.394 9(3)nm,α=61.714(3)°,β=71.495(4)°,γ=79.575(4)°,V=1.543 7 nm3,Z=2,ρ=1.481 g/cm3,C28H31CoN5O12,Mr=688.51,F(000)=714 andμ=0.627 mm-1,7 754个独立衍射点中,5 428个可观察点满足I≥2σ(I),R1=0.074 5,wR2=0.210 7.晶体中[Co(Phen)2(H2O)2]2+通过π-π相互作用堆积成二维层状结构,层间通过氢键作用构成三维超分子.     

In[NC5H3(CO2)2](OH2)F: A new layered indium-organic framework material (NC5H3(CO2)2=2,6-pyridinedicarboxylate)

A new layered indium-organic framework material, In[NC₅H₃(CO₂)₂](OH₂)F has been synthesized by a hydrothermal reaction using In₂O₃, NH₄F, 2,6-NC₅H₃(CO₂H)₂ (2,6-pyridinedicarboxylic acid), HF, and water at 200 °C. Single-crystal X-ray diffraction was used to determine the structure of the reported material. In[NC₅H₃(CO₂)₂](OH₂)F has a novel layered structure consisting of InO₅NF polyhedra and the pyridinedicarboxylate organic linker. Detailed structural analyses with full characterization including infrared spectrum, thermogravimetric analysis, elemental analysis, exchange reactions for the coordinated water molecule, and gas adsorption experiments are reported.     

Efficient Degradation of Cellulose in Its Homogeneously Aqueous Solution over 3D Metal-Organic Framework/Graphene Hydrogel Catalyst

Catalytic degradation of cellulose to chemicals is an attracting topic today for the conversion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks (MOFs) possess uniform, continuous, and permeable channels, they are valuable candidate as catalysts. Here, a new 3D MOF/graphene catalyst was prepared by in situ growth of the zeolitic imidazolate frameworks (ZIF-8) nanoparticles inside the pore of an as-formed 3D reduced graphene oxide (rGO) hydrogel. The ZIF-8/rGO nanocomposite owns both micropores and mesopores with large specific surface area and plenty of acids sites, which is an idea catalyst for biomass degradation. Cellulose was dissolved in alkaline aqueous solution at first, and then it was degraded efficiently over the new catalyst under hydrothermal condition. The conversion reaches 100% while the main products are formic acid with a maximum yield of 93.66%. In addition, the catalyst can be reused with high activity.     

A two‐dimensional zinc(II) coordination polymer based on mixed dimethyl succinate and bipyridine ligands: synthesis,structure, thermostability and luminescence properties

From the viewpoint of crystal engineering, the construction of crystalline polymeric materials requires a rational choice of organic bridging ligands for the self‐assembly process. Multicarboxylate ligands are of particular interest due to their strong coordination activity towards metal ions, as well as their various coordination modes and versatile conformations. The structural chemistry of dicarboxylate‐based coordination polymers of transition metals has been developed through the grafting of N‐containing organic linkers into carboxylate‐bridged transition metal networks. A new luminescent two‐dimensional zinc(II) coordination polymer containing bridging 2,2‐dimethylsuccinate and 4,4′‐bipyridine ligands, namely poly[[aqua(μ₂‐4,4′‐bipyridine‐κ²N:N′)bis(μ₃‐2,2‐dimethylbutanedioato)‐κ⁴O¹,O^1′:O⁴:O^4′;κ⁵O¹:O¹,O⁴:O⁴,O^4′‐dizinc(II)] dihydrate], {[Zn₂(C₆H₈O₄)₂(C₁₀H₈N₂)(H₂O)]·2H₂O}_n, has been synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction and elemental, IR and thermogravimetric analyses. In the structure, the 2,2‐dimethylsuccinate ligands link linear tetranuclear Zn^II subunits into one‐dimensional chains along the c axis. 4,4′‐Bipyridine acts as a tethering ligand expanding these one‐dimensional chains into a two‐dimensional layered structure. Hydrogen‐bonding interactions between the water molecules (both coordinated and free) and carboxylate O atoms strengthen the packing of the layers. Furthermore, the luminescence properties of the complex were investigated. The compound exhibits a blue photoluminescence in the solid state at room temperature and may be a good candidate for potential hybrid inorganic–organic photoactive materials.     

金属有机框架材料吸附性能应用的研究

金属有机框架材料(MOFs)是一种多孔聚合物材料,其相关研究近年来取得迅速发展。MOFs是以金属离子为中心,桥连的有机配体作为支撑经延伸形成的一类具有周期性网络结构的晶态多孔材料[1]。由于其较强的功能性、较高的比表面积、超高的孔隙率以及可调控的孔道结构[2],MOFs在储气、分离、催化、载药和光学等领域受到了极大的重视,并具有广泛的应用前景。本文从MOFs材料的结构设计出发,介绍近几年MOFs材料在能源气体(H2、CH4)的储存,H2S、CO2、有机气体分子的捕集以及医学领域(对于一些药物的吸附装载)的研究进展,并对MOFs材料在应用上存在的问题进行了阐述,对其未来的发展趋势作出展望。     

Investigating metal-organic framework as a new pseudo-capacitive material for supercapacitors

A new application of metal organic framework （MOF） as a pseudo-capacitive material for supercapacitors is investigated. To this end, a simple nickel-based MOF, formulated Ni3（btc）2.12H2O, is synthesized via a hydrothermal reaction. As an electro-active material, such nickel-based MOF exhibits superior pseudo- capacitive behavior in KOH aqueous electrolyte with a high specific capacitance of 726 F g-1. Also, it displays good electrochemical stability with 94.6% of the initial capacitance over consecutive 1000 cycles. In addition, a simple asymmetric supercapacitor with a high energy density of 16.5 Wh kg-1 is successfully built using the nickel-based MOF as positive electrode and commercial activated carbon as negative electrode in KOH electrolyte.     

金属-有机框架衍生的中空碳材料及其在电化学能源存储与氧还原领域中的应用

金属-有机框架材料(metal-organic frameworks,MOFs)是一类由金属离子或金属团簇与有机配体通过配位键连接形成的具有周期性网络结构的多孔配位聚合物。这类材料通常具有孔道规整、比表面积大、孔隙率高、结构可设计及孔壁易修饰等特点,诸多的优点使得MOFs的研究从配位化学跨越到多个学科领域,成为当前多学科交叉前沿热点之一。近来的研究发现,以MOFs为前驱体碳化后制得的碳材料可保留MOFs的大比表面积和多孔结构,同时可以实现均匀的杂原子(如N、P、S、B等)掺杂,而且通过选择合适的MOFs前驱体可调控产物的组成和形貌尺寸,这些显著的结构特征使其具备了成为高性能功能性材料的潜力。最近,以MOFs为模板或前驱体制备的中空碳材料引起了人们的广泛关注,这主要是因为中空结构可有效缓解材料在电化学过程中产生的体积变化及受到的冲击,而且中空结构可暴露出更多的活性位点,具有快速的传质过程,使得材料发挥出最优性能,故而此类材料可被用在二次电池、电容器、电催化等多种电化学器件和多个领域中。基于此,本文综述了MOFs衍生的中空碳材料在储能器件及电催化领域的研究进展,主要包括锂离子电池、锂硫/硒电池、钠离子电池、超级电容器、电催化氧还原等领域,并对这类材料当前面临的挑战及未来的发展趋势进行了阐述。     

Nanosized Functional MOFs Loading Ag/AgBr with Throughout‐Visible‐Light Absorption for High‐Efficiency Photocatalysis

Porous metal‐organic frameworks (MOFs) loading metal nanoparticles to form a composite photocatalyst demonstrated unique advantages. Modification of the electron donating group on the aromatic linkers of MOFs could increase the absorption range of light, thereby increasing the photocatalytic activity. In this study, we prepared a composite photocatalyst using a stable NH₂‐functionalized MOF (UiO‐66‐NH₂) to load semiconductor Ag/AgBr nanoparticles, and the resultant composites have intense optical absorption throughout visible light range. The greatly enhanced optical absorption and the unique hetero‐junction between Ag/AgBr and UiO‐66‐NH₂ render efficient separation and utilization of photogenerated electron‐hole pairs. Therefore, Ag/AgBr@UiO‐66‐NH₂ showed much more excellent photocatalytic activity, compared with unmodified UiO‐66 loading Ag/AgBr (Ag/AgBr@UiO‐66) and reported AgX@MOF catalysts. Moreover, the composite photocatalysts showed excellent stability during cycling experiment.