聚合物-金属有机框架材料的研究进展

金属有机框架（MOFs）因其大孔隙率、高比表面积和规则可调的孔径结构等优势受到了广泛关注,然而该材料较差的热塑性和力学性能限制了其可加工性,不利于大规模工业应用。为解决此问题,研究者们将聚合物作为多孔材料的一部分,通过直接或间接的方法合成了一种三维且高度多孔的材料——聚合物-金属有机框架（polymer-metal-organic frameworks, polyMOFs）。此材料兼具MOFs出色的性能与聚合物的可加工性,在气体分离、生物医用和催化等领域具有广阔的应用前景。本文综述了polyMOFs的三种合成方法,包括合成后聚合、单晶到单晶转换和直接合成法,介绍了三种方法的特点与不足,并展望了未来polyMOFs的发展方向。     

构筑手性金属有机骨架的方法及其在不对称催化中的应用

手性金属有机骨架(MOF)具有独特的结构、不对称催化和手性拆分等性能,引起了催化学者的极大重视.系统地介绍了国内外有关手性MOF的合成方法,即:①非手性物质在晶体生长过程中自组装;②使用手性化合物来诱导合成;③通过手性有机基团与金属离子配位将手性成分嵌入金属有机骨架;④表面修饰的方法,第3种方法是最常用的合成手性MOF的方法.重点阐述了近年来手性MOF在不对称催化领域的最新研究成果,希望能为手性MOF研究者设计、合成更优良的手性MOF催化剂提供参考.未来手性MOF催化的主要目标在于合成性能更加高效、稳定的新型手性MOF催化剂,并应用于大规模工业生产中,在温和条件下实现较高的转化数和对映体选择性.     

Acid-base properties and catalytic activity of metal-organic frameworks: A view from spectroscopic and semiempirical methods

This article summarizes several approaches for understanding the catalytic chemistry and “structure-surface acidity-reactivity” relationships in a multiplicity of catalytic applications of a continually increasing assemblage of metal-organic frameworks (MOFs) structures. The various spectroscopic techniques for acid-base characterization of MOFs are reviewed. The experimental requirements and the type and nature of probe molecules available are also discussed. Special emphasis is given to the revealing of the surface acid-base effect on the catalytic performance of MOFs.     

金属有机骨架材料多功能阻燃聚合物应用研究进展

简要介绍了具有高孔隙率、催化吸附等特性的金属有机骨架(MOFs)材料的分类及合成方法,分别从改性以及未改性MOFs材料在聚合物中的阻燃应用及阻燃机理来阐述了近年来MOFs材料在聚合物材料阻燃方面的研究现状.最后,对其MOFs材料的应用前景进行了总结与展望.     

Large‐scale computational screening of metal‐organic frameworks for CH4/H2 separation

Molecular simulations were performed to study a diverse collection of 105 metal‐organic frameworks (MOFs) for their ability to remove CH₄ from CH₄/H₂ mixture. To investigate the practical industrial application in a pressure swing adsorption (PSA) process, working capacity was also considered in addition to selectivity. The results show that MOFs are promising candidate for this separation, which give higher adsorption selectivity with similar working capacity and higher working capacity with similar selectivity than the traditional nanoporous materials such as carbonaceous materials and zeolites. To quantitatively describe the structure–property relationship for CH₄/H₂ mixture separation in MOFs, a new concept named “adsorbility” was defined, which shows strong correlation with limiting selectivity, with a correlation coefficient (r²) of 0.86. This work shows that although MOFs are promising materials for CH₄/H₂ mixture separation, more investigations that consider both selectivity and working capacity are necessary to screen MOFs in practical PSA application. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

金属有机框架材料的绿色合成

金属有机框架化合物（Metal-organic frameworks,简称MOFs）是由金属离子（或簇）与有机配体配位并经由自组装而形成的一类多孔材料^[1]。MOFs具有极其发达的孔道结构,比表面积和孔容远超其他多孔材料。有机/无机杂化这一特点也赋予了MOFs其他材料（例如沸石、活性炭等）所不具备的无限结构功能可调性^[2]。此外,MOFs具有移除客体分子而主体框架完好保持的持久孔道或孔穴,这使得MOFs具有超乎寻常的化学及物理稳定性。正是基于以上这些特点,MOFs在许多领域有着丰富的应用^[3-4],例如催化^[5]、H₂储存^[6]、CO₂捕集^[7]、药物运输^[8]、污染物吸附^[9]、生物医学成像^[10]等方面。MOFs的商业化探索成为了目前的热点。MOFs的很多应用都与可持续发展及“绿色材料”有关,但MOFs本身的合成过程也需要考虑可持续性和环境影响。金属有机化学所面临的环境挑战是独特的,因为它将金属离子、有机配体的危害联系在一起,且合成过程大多需要大量能耗。主要介绍了金属有机框架材料的绿色可持续合成,主要分为4个方面：1）使用更安全或生物相容性的配体;2）使用更绿色、低成本的金属源;3）绿色溶剂的开发;4）无溶剂合成法。     

光子功能金属-有机框架材料研究进展

金属-有机框架材料是一种由金属离子或金属簇与有机桥联配体通过配位作用组装形成的新型无机-有机复合多孔材料.无机、有机组分在分子水平的复合使得框架材料能够兼具无机和有机基元各自的特点和性能并产生协同作用,有序微孔则为组装客体分子实现光子学性能的调控甚至新光子功能的出现提供了可能.金属-有机框架材料在发光和非线性光学等光子...     

Surface-Initiated Controlled Radical Polymerization in Ordered Mesoporous Silicas

Recent advances in the synthesis of well-defined high-surface-area mesoporous silica/polymer composites via surface-initiated polymerization (“grafting from” method) and via attachment of preformed polymer chains (“grafting to” method) to surfaces of ordered mesoporous silicas (OMSs) are reviewed in the context of related research areas. Prior work on polymerizations in nanoscale confinements of OMSs is outlined and surface-initiated polymerization in disordered mesoporous silicas is briefly discussed. Early work on the surface-initiated radical polymerization initiated from OMS surface is reviewed and recent work involving OMS supports with large mesopores is discussed to illustrate the ability to form well-defined polymer brushes in nanopores using atom transfer radical polymerization (ATRP). The synthesis of polymer brushes in mesopores through the combination of ATRP or other polymerizations and the “click” chemistry is also outlined.     

Supramolecular Chemistry in Solid State Materials such as Metal-Organic Frameworks

Supramolecular chemistry has enriched the scientific research for more than fifty years reaching one of its summits in 2016, when the Chemistry Nobel Prize was awarded for the design and synthesis of molecular machines, in which host-guest chemistry plays a fundamental role. Recently, the groups of Omar Yaghi and Fraser Stoddart, among others, have demonstrated that this chemistry can be extended to the pores of metal-organic frameworks (MOFs). This heterogenization of supramolecular chemistry can be achieved through the incorporation of macrocycles to the organic struts of these highly porous and crystalline materials. Throughout this short review we summarize interesting examples of selective recognition by naturally occurring and synthetic macrocycles in solution and solid state; and later we survey important milestones to achieve specific recognition sites and develop host-guest chemistry at the pores of MOFs. This summary contains examples of different synthetic strategies to incorporate macrocycles to solid state materials, and in particular, to prepare supramolecular MOFs with particular properties and related applications. Specifically, the revised research includes the incorporation of both naturally occurring and synthetic macrocycles to solid state materials such as polymers, metal nanoparticles, etc., as prelude of the solid phase recognition studied in MOFs. An important number of the contributions presented here feature porous solids with smooth access to the host's cavity incorporated in the pores, allowing specific recognition of guest molecules. This smooth access to those active recognition sites in materials with extremely high surface area such as MOFs, open the possibility to develop the next generation of frontier materials with application in fields such as selective capture of water toxins and heterogeneous catalysis, among others.     

Emerging Synthetic Methods and Applications of MOF-Based Gels in Supercapacitors,Water Treatment,Catalysis, Adsorption,and Energy Storage

Metal–organic frameworks (MOFs), which are synthesized through the self-assembly of organic ligands and inorganic metals, have drawn considerable research interest owing to their unique properties and attractive structures. Many studies on various MOF derivatives, such as MOFs and cellulose aerogels, hydrogel composite materials, and bimetallic-centered MOF materials, have provided the potential for wide application of MOFs. However, MOFs mostly exist in the form of powder particles, which are difficult to form. In addition, MOFs have problems with structural instability. MOF-based gels can overcome this problem. MOF-based gels also have significant advantages in secondary processing. In this review, synthetic methods for MOF-based gels, particularly the synergistic effect with other materials, are introduced. The applications of MOF-based hydrogels and aerogels in supercapacitors, water treatment, catalysis, adsorption, and energy storage are also discussed.     

Grafting of a liquid crystal polymer on carbon fibers

Covalent grafting of mesogenic chains on carbon fiber surfaces was attempted as part of a study on composite materials containing liquid crystal polymer matrices. Grafting in these composite systems is viewed not only as a mechanism to achieve interfacial bonding but also as an approach to modify the interphase physical structure. The synthetic approach to grafting involved the in-situ polymerization of monomers in the presence of functionalized fibers in order to grow chains covalently attached to the fibers. The chemical mechanism may be viewed as the “transesterification of car boxy lated fibers” with acetylated monomers. The monomers used were pimelic acid, p-acetoxybenzoic acid and diacetoxy hydroquinone which are known to yield upon condensation a chemically aperiodic nematic polymer. Evidence for grafting was obtained from X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis on fibers retrieved from composite samples. Interestingly, SEM micrographs of fractured composite specimens containing the mesogen-grafted fibers reveal excellent wetting and interfacial bonding of a liquid crystalline matrix on the carbon surfaces. Based on theoretical considerations for end-adsorbed macromolecules and the nematogenic nature of the grafted chains we infer that dense layers of adsorbed polymer may form at the interfaces studied. From a materials point of view the in situ growth of liquid crystal polymer chains on fibers may offer mechanisms to control composite properties through both bonding and molecular orientation in interfacial regions.     

Electroactive Metalorganic Frameworks

Crystalline and porous framework materials with appreciable charge carrier mobility hold promise as a new semiconducting platform. Through the concepts of reticular chemistry, numerous two- and three-dimensional crystalline and porous frameworks with encoded properties enabling significant electrical conductivity are in reach. Prominent members of this group are the metal-organic frameworks (MOFs), which recently created scientific excitement as highly conductive materials. Herein, we discuss the recent prominent examples reported for electrically conducting MOFs with regards to their synthesis, structural and electronic properties and possible applications. We frame our discussion according to structural features of the MOFs, covering both layered 2D and 3D frameworks.     

New Application of Hydroxyl Groups: Ligands for High Density Metal Organic Frameworks

Energetic metal organic frameworks (MOFs) with energetic anions as ligands can be used as new‐generation explosives. Many powerful anions have been introduced into energetic MOFs to improve the properties; however, the hydroxyl as a common group for energetic MOFs has rarely been studied. In this article, we present two examples of energetic MOFs ([Cu(atz)(NO₃)(OH)]_n) and [Zn(ata)(OH)] (atz=4‐amino‐1,2,4‐triazole; ata=5‐amino‐1H‐tetrazole) with the hydroxyl group as the ligand. Crystal structure analyses reveal that the two compounds possess compact two‐dimensional (2‐D) structures with densities up to 2.41 g cm⁻³ and 2.54 g cm⁻³, respectively. These two compounds have excellent physicochemical properties. The results demonstrate that a hydroxyl group as the ligands could commendably increase the densities of energetic MOFs, thereby enhancing the detonation performance. It is anticipated this work will open a new direction for the development of energetic MOFs.     

Flame‐based synthesis and in situ functionalization of palladium alloy nanoparticles

Flame‐driven synthesis and functionalization of palladium‐containing nanoparticles is demonstrated using a high temperature reducing jet (HTRJ) process that decouples flame chemistry from particle formation chemistry and provides a reducing environment that enables synthesis of metal nanoparticles from low‐cost aqueous precursors. Nanoparticles with controlled palladium, copper, and silver content were synthesized and functionalized with amine‐containing ligands using both in situ and ex situ approaches. For in situ functionalization, octylamine was sprayed into the quench section of the HTRJ reactor to cap the nanoparticles in the gas phase. For the ex situ approach, the “bare” nanopowders were heated in various amines (hexylamine, octylamine, and oleylamine) to form stable dispersions. Use of oleylamine at high temperature allowed modification of the nanoparticle size and shape while maintaining the alloy composition. These in situ and ex situ functionalization methods provide flexibility to tailor particles for specific applications such as electrocatalysis or hydrogen purification. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3826–3834, 2018     

金属有机骨架固载离子液体复合材料研究进展

离子液体是一种由阴离子和阳离子共同组成的有机熔融盐，其挥发性低、热稳定性和化学稳定性好、电化学窗口宽、结构可调变，近年来在诸多领域具有广泛的应用。但由于其黏度大不便于输送和操作，合成成本较高、回收利用率低等缺点，其发展受到了一定的限制。金属有机骨架 (MOFs) 材料是由金属离子/团簇和有机配体通过配位键自组装形成的具有分子内孔隙结构的有机-无机杂化材料。以MOFs为载体固载离子液体，不仅可以保留离子液体的优势，还可以赋予离子液体而很多新的特性。本文从MOFs固载离子液体的理论计算和实验应用研究出发，综述了MOFs固载离子液体的起源和固载方式，分析了MOFs和离子液体之间的兼容性、固载形式和相互作用，并对MOFs固载离子液体的瓶颈问题进行了分析，对发展方向进行了展望。     

Reverse selectivity of zeolites and metal-organic frameworks in the ethane/ethylene separation by adsorption

Major advances in the ethane/ethylene separation will be related with the discovery of adsorbents that present preferential adsorption of ethane over ethylene. Metal-organic frameworks (MOFs) are crystalline materials consisting of metal ions, or ion clusters, and organic ligands. Gas chromatography (GC) is most informative for materials screening for the ethane/ethylene separation since it needs only few mg of sample and gives selectivity results at various temperatures. This is illustrated by the methodology presented in this work where materials from two types of families (zeolites and MOFs) were used to show the reversed selectivity that can be found towards the ethane/ethylene separation.     

金属有机框架材料中的质子传导及其在质子交换膜中的应用

质子交换膜（proton exchange membrane，PEM）是保证燃料电池安全、高效运行的关键部件。当前，Nafion及部分Nafion衍生物PEM被广泛应用于燃料电池、电解制氢、传感检测、液流电池等领域。但是，其仍存在制造成本过高、高效温度范围狭窄（\mathrm{约}\mathrm{20}~\mathrm{80}℃）等问题。近年来，部分金属有机框架材料（metal-organic frameworks，MOFs）因具有结晶性、可设计性和高比表面积等优点，作为潜在的新型质子导体，被用于修饰、改进现有高分子质子交换膜，或直接被作为主要质子传导介质制成质子交换膜，取得了一系列重要进展。本文详细介绍了在MOFs中五种质子传导的常见方式，综述了近年来国内外在高性能质子传导MOFs领域的代表性成果，总结了质子传导MOFs在质子交换膜中的三类常见应用方法，指出MOFs材料在提高PEM质子电导率、降低PEM成本、拓宽PEM高效工作区间等方面具有巨大的发展潜力。最后，本文提出现有MOFs在质子交换膜中的应用还存在稳定性、耐久性、有害物质逸出等方面的问题，这为新型MOFs质子交换膜的开发提供了参考与思路。     

纳米MOFs及其衍生物在超级电容器中的研究进展

金属有机框架（MOFs）材料因其大的比表面积、可调控的孔道结构和丰富的活性位点引起了国内外学者们的广泛关注。近年来MOFs基材料广泛应用于能量储存与转化领域,但大多数MOFs基材料的低稳定性和低导电性等缺陷限制了其实际应用。通过对MOFs基材料进行改性,如采用共轭度高的有机配体以增加MOFs材料的稳定性,或MOFs衍生物以提高其氧化还原活性位点和导电性,从而达到提高MOFs基电极材料的电化学性能。主要介绍了原始MOFs及其衍生材料如碳材料、金属氧化物、金属硫化物、金属氢氧化物和金属磷化物等在超级电容器电极材料中的最新研究进展。研究表明,多金属MOFs材料或多金属MOFs衍生物有利于提高电极材料的电化学性能,而导电MOFs材料或MOFs衍生物中的碳材料有利于提高电极材料的导电性。最后对MOFs基电极材料在电化学储能领域中的研究做出了展望,指出MOFs基材料的形貌、组分和导电性是未来研究的发展方向。     

疏水性金属-有机骨架材料的研究进展

金属-有机骨架（metal-organic frameworks, MOFs）材料是一种由金属离子和有机配体通过自组装形成的新型多孔材料,具有优异的物理及化学性能,因而在气体吸附储存、气体分离以及工业催化等方面表现出良好的应用潜力。但在应用的过程中,无处不在的水分子会影响MOFs骨架的稳定性和吸附性能,极大地制约了其实际应用。本文介绍了近年来疏水性MOFs材料的研究进展,重点论述了金属离子和有机配体对调控MOFs亲疏水性的影响以及通过配体后修饰和疏水性物质复合等提高疏水性的方法,分析了MOFs材料的亲疏水性机理,同时提出了实验结合计算机模拟技术筛选疏水性MOFs的手段。最后,指出目前疏水性MOFs材料合成存在的问题及解决方法,期望为今后拓宽MOFs材料在高湿环境中的应用提供一些有用的参考。     

Tuning the topology and functionality of metal-organic frameworks by ligand design

Metal-organic frameworks (MOFs)-highly crystalline hybrid materials that combine metal ions with rigid organic ligands-have emerged as an important class of porous materials. The organic ligands add flexibility and diversity to the chemical structures and functions of these materials. In this Account, we summarize our laboratory's experience in tuning the topology and functionality of MOFs by ligand design. These investigations have led to new materials with interesting properties. By using a ligand that can adopt different symmetry conformations through free internal bond rotation, we have obtained two MOFs that are supramolecular stereoisomers of each other at different reaction temperatures. In another case, where the dimerized ligands function as a D(3)-Piedfort unit spacer, we achieve chiral (10,3)-a networks. In the design of MOF-based materials for hydrogen and methane storage, we focused on increasing the gas affinity of frameworks by using ligands with different geometries to control the pore size and effectively introduce unsaturated metal centers (UMCs) into the framework. Framework interpenetration in PCN-6 (PCN stands for porous coordination network) can lead to higher hydrogen uptake. Because of the proper alignment of the UMCs, PCN-12 holds the record for uptake of hydrogen at 77 K/760 Torr. In the case of methane storage, PCN-14 with anthracene-derived ligand achieves breakthrough storage capacity, at a level 28% higher than the U.S. Department of Energy target. Selective gas adsorption requires a pore size comparable to that of the target gas molecules; therefore, we use bulky ligands and network interpenetration to reduce the pore size. In addition, with the help of an amphiphilic ligand, we were able to use temperature to continuously change pore size in a 2D layer MOF. Adding charge to an organic ligand can also stabilize frameworks. By ionizing the amine group within mesoMOF-1, the resulting electronic repulsion keeps the network from collapsing, giving rise to the first case of mesoporous MOF that demonstrates the type IV isotherm. We use dendritic hexacarboxylate ligands to synthesize an isoreticular series of MOFs with (3,24)-connected network topology. The cuboctahedral cages serve as building blocks that narrow the opening of the mesocavities into microwindows and stabilize these MOFs. The resulting materials have exceptionally high surface areas and hydrogen uptake capacities. Despite the many achievements in MOF development, there is still ample opportunity for further exploration. We will be continuing our efforts and look forward to contributing to this blossoming field in the next decade.