Recent advances in the recovery of tungsten values in the fine and ultrafine size range

Recent advances in the design of fine gravity concentrators and high gradient magnetic separation devices have led to significant improvements in the recovery of tungsten values in fine and ultrafine size range. Amongst the more promising techniques of fine particles processing, encouraging results are reported on froth flotation, shear flocculation and spherical agglomeration of tungsten ore slimes. Development of highly selective reagents such as alkyl hydroxamates, phosphonic acid derivatives and alkylated nitrosonapthols is vital for enhancing separation efficiencies in the slimes size range. Froth flotation of Indian tungsten ore slimes (particularly at Degana) using appropriate reagent combinations appears promising and needs to be examined in greater detail.     

Bioengineering of nano metal-organic frameworks for cancer immunotherapy

Immunotherapy techniques,such as immune checkpoint inhibitors,chimeric antigen receptor(CAR)T cell therapies and cancer vaccines,have been burgeoning with great success,particularly for specific cancer types.However,side effects with fatal risks,dysfunction in tumor microenvironment and low immune response rates remain the bottlenecks in immunotherapy.Nano metal-organic frameworks(nMOFs),with an accurate structure and a narrow size distribution,are emerging as a solution to these problems.In addition to their function of temporospatial delivery,a large library of their compositions,together with flexibility in chemical interaction and inherent immune efficacy,offers opportunities for various designs of nMOFs for immunotherapy.In this review,we overview state-of-the-art research on nMOFs-based immunotherapies as well as their combination with other therapies.We demonstrate that nMOFs are predominantly customized for vaccine delivery or tumor-microenvironment modulation.Finally,a prospect of nMOFs in cancer immunotherapy will be discussed.     

Functionalization of silicon nanowire surfaces with metal-organic frameworks

Metal-organic frameworks (MOFs) and silicon nanowires (SiNWs) have been extensively studied due to their unique properties; MOFs have high porosity and specific surface area with well-defined nanoporous structure, while SiNWs have valuable one-dimensional electronic properties. Integration of the two materials into one composite could synergistically combine the advantages of both materials and lead to new applications. We report the first example of a MOF synthesized on surface-modified SiNWs. The synthesis of polycrystalline MOF-199 (also known as HKUST-1) on SiNWs was performed at room temperature using a step-by-step (SBS) approach, and X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy elemental mapping were used to characterize the material. Matching of the SiNW surface functional groups with the MOF organic linker coordinating groups was found to be critical for the growth. Additionally, the MOF morphology can by tuned by changing the soaking time, synthesis temperature and precursor solution concentration. This SiNW/MOF hybrid structure opens new avenues for rational design of materials with novel functionalities.      

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。     

Non-carboxylate based metal-organic frameworks (MOFs) and related aspects

The metal-organic frameworks, in recent years, show a variety of new developments that includes new methods of preparation, post synthesis modifications and novel class of compounds. Though most of the developments happened in the carboxylate based family of compounds, the other related systems are also equally interesting. In this article, we have highlighted some of the developments that have taken place in the family of non-carboxylate metal-organic frameworks. We have also highlighted some of the recent attempts at modifying the surfaces and pores of the MOFs by careful chemical manipulations.     

Let the light be a guide: Chromophore communication in metal-organic frameworks

The photonic characteristics of chromophore-containing metal-organic frameworks(MOFs)have led to extensive photophysical studies in an effort to capitalize on the potency of precisely controlled chromophore ensembles.Several examples have laid the foundation that demonstrates how photophysical properties of chromophores can be manipulated by tuning their communications(interactions)through integration within a MOF matrix.The main focus of this review is on harnessing the versatile MOF platform to accentuate the photophysical properties of integrated chromophores.In particular,this review will highlight chromophore dynamics that enhance,alter,or tune the photoluminescence response of single-and multi-chromophore-containing scaffolds,as well as alignment-guided anisotropic fluorescence.Building upon this groundwork,utilization of a hybrid crystalline motif can induce preferential orientation of chromophores resulting in enhanced communication and tailored behavior compared to randomly oriented emissive molecules.Moreover,frameworks that produce upconverted emission via sensitized triplet-triplet annihilation(sTTA),excited-state absorption(ESA),energy transfer upconversion(ETU),multi-photon absorption(MPA),or second-harmonic generation(SHG)can invoke dynamic control of material properties using photochromic linkers and will be discussed herein with a focus on the effects of chromophore alignment.Integration within a framework is a vehicle tofuse chromophores into solid-state platforms,opening an avenue for chromophore utilization in applications such as portable electronics that require solids or thin films.For those reasons,the design of chromophore-containing MOFs with desirable properties that rely on the alignment and communication of hundreds of chromophores within a single platform is a pressing demand for the development of futuristic technologies.     

Solvothermal synthesis of La-based metal-organic frameworks and their color-tunable photoluminescence properties

A series of La-based metal?organic frameworks (La-MOFs) phosphors have been successfully synthesized by a facile solvothermal method without assistance of any surfactant or template. The results show that the ethanol volume ratio is important to obtain adjustable shape and size of La-MOFs in the synthesis process. The obtained samples possess flake-like architectures with about 3–5 μm in length. Under UV excitation, all the La-MOFs:Tb³⁺, Eu³⁺ phosphors exhibit the characteristic emissions of Tb³⁺ and Eu³⁺. Moreover, the emitting color of the as-obtained products can be acquired from green, green-yellow, yellow, yellow-orange, orange, to red owing to the efficient energy transfer (ET) between Tb³⁺ and Eu³⁺ions. The ET efficiency of the samples was calculated, and the maximum was found about 96.84%. Furthermore, the dipole–quadrupole interaction has been reasonable proved by the energy transfer between Tb³⁺ and Eu³⁺. These results indicated that La-MOFs:Tb³⁺, Eu³⁺ might be as a novel potential candidate as phosphors for displays and lightings.

     

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...     

金属-有机骨架抗菌复合材料与纤维的研究进展及应用

金属-有机骨架(MOFs)抗菌材料因其具有比表面积大、孔隙率高且孔径可调及良好的生物相容性等优点而备受关注,是开发高效可循环使用抗菌医护口罩的热点材料.本文首先分析了MOFs抗菌复合材料的特点及其抗菌机制,然后综述了Ag、Cu、Zn基几类常用MOFs抗菌复合材料及其纤维的研究进展,最后探讨了MOFs抗菌功能纺织品在医疗...     

金属-有机骨架材料水相合成路线研究进展

金属-有机骨架材料具有优异的物理化学性质,因而在气体储存、吸附分离、药物传输、超级电容器、催化等领域具有广阔的应用前景.然而大多数金属-有机骨架材料的合成通常需要用到大量的有机溶剂,而这些有机溶剂的使用不仅会增加金属-有机骨架材料的生产成本,且极易对环境造成影响.基于此,理想的合成路线是用水代替有害的有机溶剂,以降低成本及减轻其对环境的影响.本文总结了近期金属-有机骨架材料水相合成路线的研究进展,重点概括了不同水相合成法制备金属-有机骨架材料的机理,并分析了各种方法的优缺点.此外,还讨论了当前绿色且低成本工业化生产金属-有机骨架材料存在的问题以及未来可能的发展方向.     

聚甲基丙烯酸甲酯改性研究进展

综述了聚甲基丙烯酸甲酯(PMMA)在耐热性能、耐磨损性能、阻燃等方面改性研究的途径及国内外研究的最新进展,分析了各种改性方法的特点,并展望了PMMA改性研究今后的发展方向.     

Spatial compartmentalization of metal nanoparticles within metal-organic frameworks for tandem reaction

Fabrication of multifunctional catalysts has always been the pursuit of synthetic chemists due to their efficiency,cost-effectiveness,and environmental friendliness.However,it is difficult to control multi-step reactions in one-pot,especially the spatial compartmentalization of incompatible active sites.Herein,we constructed metal-organic framework(MOF)composites which regulate the location distribution of metal nanoparticles according to the reaction path and coupled with the diffusion of substrates to achieve tandem reaction.The designed UiO-66-Pt-Au catalyst showed good activity and selectivity in hydrosilylation-hydrogenation tandem reaction,because the uniform microporous structures can control the diffusion path of reactants and intermediates,and Pt and Au nanoparticles were arranged in core-shell spatial distribution in UiO-66.By contrast,the low selectivity of catalysts with random deposition and physical mixture demonstrated the significance of artificial control to the spatial compartmentalization of active sites in tandem catalytic reactions,which provides a powerful approach for designing high-performance and multifunctional heterogeneous catalysts.     

Chiral metal-organic frameworks with tunable catalytic selectivity in asymmetric transfer hydrogenation reactions

Metal-organic frameworks(MOFs)have achieved great success in the field of heterogeneous catalysis,however,ifs still challenging to design MOF catalysts with enhanced selectivity.Here,we demonstrated a combination strategy of metal design and ligand design on the enantioselectivity—that is the enantioselectivities of chiral MOF(CMOF)catalysts could be significantly enhanced by the rational choice of metal ions with higher electronegativities and introducing sterically demanding groups into the ligands.Four isostructural Ca-,Sr-and Zn-based CMOFs were prepared from enantiopure phosphono-carboxylate ligands of 1,V-biphenol that are functionalized with 2,4,6-trimethyl-and 2,4,6-trifluoro-phenyl groups at the Supposition.The uniformly distributed metal phosphonates along the channels could act as Lewis acids and catalyze the asymmetric transfer hydrogenation of heteroaromatic imines(benzoxazines and quinolines).Particularly,the Ca-based MOF 1 with 2,4,6-trimethyl groups at the substituents exhibited enhanced catalytic performance,affording the highest enantioselectivity(up to 97%).It is also the first report of the heterogeneous catalyst with chiral non-noble metal phosphonate active sites for asymmetric transfer hydrogenation reactions with Hantzsch ester as the hydrogen source.The catalyst design strategy demonstrated here is expected to develop new types of chiral materials for asymmetric catalysis and other chiral applications.     

Spatial compartmentalization of metal nanoparticles within metal-organic frameworks for tandem reaction

Fabrication of multifunctional catalysts has always been the pursuit of synthetic chemists due to their efficiency,cost-effectiveness,and environmental friendliness.However,it is difficult to control multi-step reactions in one-pot,especially the spatial compartmentalization of incompatible active sites.Herein,we constructed metal-organic framework(MOF)composites which regulate the location distribution of metal nanoparticles according to the reaction path and coupled with the diffusion of substrates to achieve tandem reaction.The designed UiO-66-Pt-Au catalyst showed good activity and selectivity in hydrosilylation-hydrogenation tandem reaction,because the uniform microporous structures can control the diffusion path of reactants and intermediates,and Pt and Au nanoparticles were arranged in core-shell spatial distribution in UiO-66.By contrast,the low selectivity of catalysts with random deposition and physical mixture demonstrated the significance of artificial control to the spatial compartmentalization of active sites in tandem catalytic reactions,which provides a powerful approach for designing high-performance and multifunctional heterogeneous catalysts.     

High photoluminescent metal-organic frameworks as optical markers for the identification of gunshot residues

Gunshot residue (GSR) are solid particles produced when a firearm is discharged, and its detection is important evidence in forensic investigations. Currently, scanning electron microscopy coupled to energy dispersive spectroscopy (SEM-EDS) is the standard technique adopted for the analysis and identification of GSR; however, this methodology is inefficient for lead-free ammunition. Herein, we report the inclusion of high photoluminescent metal-organic frameworks in ammunition to allow for the visual detection of GSR. The tests indicated that marked GSR is easily visible in proportions above 5.0 wt %. A total of 1 g of marker suffices to tag 100 0.38 mm bullets or 62 0.40 mm bullets.     

Ordered structure of interlayer constructed with metal-organic frameworks improves the performance of lithium-sulfur batteries

Lithium-sulfur (Li-S) battery has attracted intensive attention in the realm of energy storage owing to its high theoretical capacity and energy density. However, the shuttle effect of soluble lithium polysulfides (LiPSs) between electrodes results in rapid capacity degradation. Herein, a strategy which combines the design of both chemical interaction and microstructure of interlayer was proposed to suppress the shuttle effect. The chemical interaction between different functionalized MOFs and LiPSs was systematically studied to find the best candidate. Furthermore, an interlayer with ordered structure was constructed via the layer-by-layer assembly of metal-organic frameworks (MOFs) on graphene (UiO-66-NH₂@graphene) to create sinuous channels which can better impede the diffusion process of LiPSs by the strong adsorption of MOF toward LiPSs. Consequently, in comparison to the battery with a bare separator, the ordered interlayer increased the initial discharge capacity of battery by 28.98% at 1.0 C and lowered the capacity decay rate remarkably from 0.10% to 0.067% per cycle, indicating that the design of chemical interaction and microstructure paves the way for high-performance Li-S batteries.

     

Combining metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs):Emerging opportunities for new materials and applications

In the past decades,metal-organic frameworks(MOFs)and covalent organic frameworks(COFs)basically enjoy the coordination chemistry and covalent chemistry,respect...