The Chemistry and Applications of Metal-Organic FrameworksHiroyasu Furukawa et al.Science 341, (2013);DOI: 10.1126/science.1230444If you wish to distribute this article to others, you can order high-quality copies for yourcolleagues, clients, or customers by clicking here.Permission to republish or repurpose articles or portions of articles can be obtained byfollowing the guidelines here.The following resources related to this article are available online atwww.sciencemag.org (this information is current as of August 29, 2013 ):Updated information and services, including high-resolution figures, can be found in the onlineversion of this article 444.full.htmlSupporting Online Material can be found /29/341.6149.1230444.DC1.htmlThis article cites 358 articles, 13 of which can be accessed 30444.full.html#ref-list-1Science (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by theAmerican Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. Copyright2013 by the American Association for the Advancement of Science; all rights reserved. The title Science is aregistered trademark of AAAS.Downloaded from www.sciencemag.org on August 29, 2013This copy is for your personal, non-commercial use only.
REVIEW SUMMARYThe Chemistry and Applicationsof Metal-Organic FrameworksREAD THE FULL ARTICLE e this article as H. Furukawa et al.,Science 341, 1230444 (2013).DOI: 10.1126/science.1230444Hiroyasu Furukawa, Kyle E. Cordova, Michael O’Keeffe, Omar M. Yaghi*Background: Metal-organic frameworks (MOFs) are made by linking inorganic and organic unitsby strong bonds (reticular synthesis). The ﬂexibility with which the constituents’ geometry, size, andfunctionality can be varied has led to more than 20,000 different MOFs being reported and studiedwithin the past decade. The organic units are ditopic or polytopic organic carboxylates (and othersimilar negatively charged molecules), which, when linked to metal-containing units, yield architecturally robust crystalline MOF structures with a typical porosity of greater than 50% of the MOFcrystal volume. The surface area values of such MOFs typically range from 1000 to 10,000 m2/g,thus exceeding those of traditional porous materials such as zeolites and carbons. To date, MOFswith permanent porosity are more extensive in their variety and multiplicity than any other class ofporous materials. These aspects have made MOFs ideal candidates for storage of fuels (hydrogenand methane), capture of carbon dioxide, and catalysis applications, to mention a few.ARTICLE OUTLINEAdvances: The ability to vary the size and nature of MOF structures without changing their underlying topology gave rise to the isoreticular principle and its application in making MOFs with thelargest pore aperture (98 Å) and lowest density (0.13 g/cm3). This has allowed for the selectiveinclusion of large molecules (e.g., vitamin B12) and proteins (e.g., green ﬂuorescent protein) andthe exploitation of the pores as reaction vessels. Along these lines, the thermal and chemical stability of many MOFs has made them amenable to postsynthetic covalent organic and metal-complexfunctionalization. These capabilities enable substantial enhancement of gas storage in MOFs andhave led to their extensive study in the catalysis of organic reactions, activation of small molecules(hydrogen, methane, and water), gas separation, biomedical imaging, and proton, electron, and ionconduction. At present, methods are being developed for making nanocrystals and supercrystals ofMOFs for their incorporation into devices.Gas Adsorption for Alternative Fuels andSeparations for Clean AirExpansion of Structures by a Factor of 2 to 17Exceptionally Large Pore AperturesHigh Thermal and Chemical StabilityPostsynthetic Modiﬁcation (PSM):Crystals as MoleculesCatalytic Transformations Within the PoresProton Conductivity for Fuel Cell ApplicationsMOF NanocrystalsThe Materials BeyondSUPPLEMENTARY MATERIALSMaterials and MethodsFigs. S1 to S8Tables S1 to S5References (135–363)Related Web sitesCambridge Structural Database reference codesfor MOFsMetal-organic framework (MOF)structures are amenable to expansion and incorporation of multiplefunctional groups within their interiors. (A) The isoreticular expansion ofMOFs maintains the network’s topologyby using an expanded version of theparent organic linker. Examples ofcatalysis in MOFs are shown in the largespace created by IRMOF-74-XI; Me is amethyl group. (B) Conceptual illustration of a multivariate MOF (MTV-MOF)whose pores are decorated by heterogeneous mixtures of functionalities thatarrange in speciﬁc sequences. (Background) Optical image of zeolitic imidazolate framework (ZIF) crystals.The list of author afﬁliations is available in the full article online.*Corresponding author. E-mail: [email protected] AUGUST 2013 VOL 341 SCIENCE www.sciencemag.orgPublished by AAASDownloaded from www.sciencemag.org on August 29, 2013Outlook: The precise control over the assembly of MOFs is expected to propel this ﬁeld further intonew realms of synthetic chemistry in which far more sophisticated materials may be accessed. Forexample, materials can be envisaged as having (i) compartments linked together to operate separately, yet function synergistically; (ii) dexterity to carry out parallel operations; (iii) ability to count,sort, and code information; and (iv) capability of dynamics with high ﬁdelity. Efforts in this directionare already being undertaken through the introduction of a large number of different functionalgroups within the pores of MOFs. This yields multivariate frameworks in which the varying arrangement of functionalities gives rise to materials that offer a synergistic combination of properties.Future work will involve the assembly of chemical structures from many different types of buildingunit, such that the structures’ function is dictated by the heterogeneity of the speciﬁc arrangementof their constituents.Design of Ultrahigh Porosity
er materials and because they lead to the previously elusive synthesis of solids by design. Unlikeother extended solids, MOFs maintain their underlying structure and crystalline order upon expansion of organic linkers and inorganic SBUs, aswell as after chemical functionalization, whichgreatly widens the scope of this chemistry. Wereview key developments in these areas and discuss the impact of this chemistry on applicationssuch as gas adsorption and storage, catalysis, andproton conduction. We also discuss the conceptof MTV-MOFs in relation to the sequence of functionality arrangement that is influenced by theelectronic and/or steric interactions among thefunctionalities. Highly functional synthetic crystalline materials can result from the use of suchtechniques to create heterogeneity within MOFstructures.The Chemistry and Applications ofMetal-Organic FrameworksHiroyasu Furukawa,1,2 Kyle E. Cordova,1,2 Michael O’Keeffe,3,4 Omar M. Yaghi1,2,4*Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which createsstrong bonds between inorganic and organic units. Careful selection of MOF constituents canyield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristicsallow the interior of MOFs to be chemically altered for use in gas separation, gas storage, andcatalysis, among other applications. The precision commonly exercised in their chemicalmodification and the ability to expand their metrics without changing the underlying topologyhave not been achieved with other solids. MOFs whose chemical composition and shape ofbuilding units can be multiply varied within a particular structure already exist and may lead tomaterials that offer a synergistic combination of properties.*Corresponding author. E-mail: [email protected] (CSD)Extended (1D, 2D, 3D)MOFs (3D)12ln(No. of structures)60005000400010Doubling time9.3 years865.7 years43.9 years2300001975 1980 1985 1990 1995 2000 2005 ment of Chemistry, University of California, Berkeley,CA 94720, USA. 2Materials Sciences Division, Lawrence BerkeleyNational Laboratory, Berkeley, CA 94720, USA. 3Department ofChemistry, Arizona State University, Tempe, AZ 87240, USA.4NanoCentury KAIST Institute and Graduate School of Energy,Environment, Water, and Sustainability (World Class University), Daejeon 305-701, Republic of Korea.70001972TDesign of Ultrahigh PorosityDuring the past century, extensive work was doneon crystalline extended structures in which metalions are joined by organic linkers containing Lewisbase–binding atoms such as nitriles and bipyridines(8, 9). Although these are extended crystal structures and not large discrete molecules such as polymers, they were dubbed coordination “polymers”—a term that is still in use today, although we preferthe more descriptive term MOFs, introduced in1995 (10) and now widely accepted. Becausethese structures were constructed from long organic linkers, they encompassed void space andtherefore were viewed to have the potential to beof MOFs with ultrahigh porosity and unusuallylarge pore openings (5). (iii) Postsynthetic modification (PSM) of MOFs—incorporating organicunits and metal-organic complexes through reactions with linkers—has emerged as a powerfultool for changing the reactivity of the pores (e.g.,creating catalytic sites) (6). (iv) Multivariate MOFs(MTV-MOFs), in which multiple organic functionalities are incorporated within a single framework,have provided many opportunities for designingcomplexity within the pores of MOFs in a controlled manner (7).Below, we focus on these aspects of MOFchemistry because they are rarely achieved in oth-No. of MOF structureshe past decade has seen explosive growthin the preparation, characterization, andstudy of materials known as metal-organicframeworks (MOFs). These materials are constructed by joining metal-containing units [secondary building units (SBUs)] with organic linkers,using strong bonds (reticular synthesis) to createopen crystalline frameworks with permanent porosity (1). The flexibility with which the metalSBUs and organic linkers can be varied has ledto thousands of compounds being prepared andstudied each year (Figs. 1 and 2). MOFs have exceptional porosity and a wide range of potentialuses including gas storage, separations, and catalysis (2). In particular, applications in energytechnologies such as fuel cells, supercapacitors,and catalytic conversions have made them objects of extensive study, industrial-scale production, and application (2–4).Among the many developments made in thisfield, four were particularly important in advancing the chemistry of MOFs: (i) The geometricprinciple of construction was realized by the linking of SBUs with rigid shapes such as squaresand octahedra, rather than the simpler node-andspacer construction of earlier coordination networks in which single atoms were linked by ditopiccoordinating linkers (1). The SBU approach notonly led to the identification of a small numberof preferred (“default”) topologies that could betargeted in designed syntheses, but also was central to the achievement of permanent porosity inMOFs (1). (ii) As a natural outcome of the use ofSBUs, a large body of work was subsequentlyreported on the use of the isoreticular principle(varying the size and nature of a structure withoutchanging its underlying topology) in the designYearFig. 1. Metal-organic framework structures (1D, 2D, and 3D) reported in the Cambridge Structural Database (CSD) from 1971 to 2011. The trend shows a striking increase during this period forall structure types. In particular, the doubling time for the number of 3D MOFs (inset) is the highestamong all reported metal-organic structures.www.sciencemag.orgSCIENCEVOL 34130 AUGUST 20131230444-1Downloaded from www.sciencemag.org on August 29, 2013REVIEW
REVIEWAM2(CO2)4(M Cu, Zn, Fe,Mo, Cr, Co, andRu)M3O(CO2)6(M Zn, Cr,In, and M3O3(CO2)3(M Zn, Mg,Co, Ni, Mn,Fe, and OOHOCOOHOHCOOHXHOOHOCOOHCOOHOxalic acidFumaricacidH2BDCXCOOHHOOCCOOHH4DOTH2BDC-X(X Br, OH,NO2, and NH2)COOHCOOHCOOHXH3BTCH2BDC-(X)2(X Me, Cl,COOH, OC3H5,and OC7H7)XH3BTE (X C C)H3BBC (X C6H4)XHOOCCOOHHN NH2H2NNHNXOCOOHOHNHOOCNCOOHN OHCOOHGly-AlaNHOOCXH3BTB (X CH)H3TATB (X HOHOHClH6TPBTM (X CONH)H6BTEI (X C C)H6BTPI (X C6H4)NH6BHEI (X C C C C)DCDPBNH6BTTI (X (C6H4)2)H6PTEI (X C6H4 C C)H6TTEI (X C C-C6H4-C C)H6BNETPI (X C C C6H4 C C C C)H6BHEHPI (X (C6H4 C C)2)OOOO ONNIrOOOONONCOOHBPP34C10DACOOHIr(H2DPBPyDC)(PPy)2 HOHOCOOHH4DH9PhDCCOOHH4DH11PhDCFig. 2. Inorganic secondary building units (A) and organic linkers (B) referred to in the text. Color code: black, C; red, O; green, N; yellow, S; purple,P; light green, Cl; blue polyhedra, metal ions. Hydrogen atoms are omitted for clarity. AIPA, tris(4-(1H-imidazol-1-yl)phenyl)amine; ADP, adipic acid; zoate.1230444-230 AUGUST 2013VOL 341SCIENCEwww.sciencemag.orgDownloaded from www.sciencemag.org on August 29, 2013Na(OH)2(SO3)3In(C5HO4N2)4HOZr6O8(CO2)8
permanently porous, as is the case for zeolites. Theporosity of these compounds was investigated inthe 1990s by forcing gas molecules into the crevices at high pressure (11). However, proof of permanent porosity requires measurement of reversiblegas sorption isotherms