WO2015035123A2 - Tunable rare-earth fcu-metal-organic frameworks - Google Patents

Abstract

Metal organic framework compositions can have a face centered cubic structure.

Description

TUNABLE RARE-EARTH CU-METAL~ORGAMC FRAMEWORKS

CLAIM OF PRIORITY

This application claims priority to U.S. Patent Application No, 14/01 ,51 1 , iikd September 3, 20.13, which is incorporated by reference its entirety.

TECHNICAL FIELD

This invention relates to rnetal-organk frameworks having tunable structures.

BACKGROUND etal-orgaaie framework ( QF) materials can have tunable properties based on their structure, including porosity. Unique porous structures ca» allow the material to be used in applications including gas sequestration, storage and separation or scrubbing.

SUMMARY

A metal- organic framework composition can have a face centered cubic (fca) structure. The composition can include a metal ioa component and a bidentate ligand component having two anionic binding groups. The two anionic binding groups are oriented 180 degrees from each other. A plurality of the metal ion component and the bidentate ligand component associate to form a 12-coanected face-centered cubi network.

A method of making a metal organic f amework composition can include contacting a metal, ion. component with a bidentate ligand component having two anionic binding groups, wherein the two anionic binding groups are oriented 180 degrees from each other, wherein the metal ion component and the bidentate ligand component associate to form a face-centered cubic network.

In. some embodiments, the metal ion component includes a rare earth (RE) metal ion. For example, the rare earth metal ion. is La, Ce, Pr, Nd, Sm, Eo, Od, Dy, Ho, Er, Tm, Yb, La, Tfe or Y, for example, terbium <Tb^3*) or yttrium (¥^"'' ^'}.

in some embodiments, the two anionic binding groups can be the same, in some embodiments, the two anionic binding groups can be the different. In certain

circumstances, each of the anionic binding groups, independently, is carboxylate or tetrazolate. Irs some embodiments, the two anionic binding groups can be linked by an aromatic group.

In some em odime ts, the aromatic group can. include a hydrophobic group. For example, the hydrophobic group can be a fluoro group. The hydrophobic group can assist in the assembly of the feu structure.

Other aspects, embodiments, ami features will be apparent from the following description, the drawings, and the claims.

DESCRIPTION OF DRAWINGS

Figure I is a drawing representing ball-and-stick and schematic representation of 1 : From top to bottom, organic and inorganic MBBs, FTZB^';~ and the i2-cormected Tb- based cluster, respectively, which can be viewed as a linear connection and enboetahedrors. node to afford the augmented feu net, consisting of octahedral and tetrahedral cages shown as blue and pink truncated polyhedron, respectively. Hydrogen atoms and coordinated water molecules are omitted for clarity- Tb ^»· green, C ~^; gray, N™ blue, O™ red, F ^{~ :} purple.

Figure 2 are graphs representing PXRD patterns for compound I : (a) after exposure to water and (b) variable temperature under a vacuum.

Figure 3 are graphs representing (a) CO? data for 1 and 2 at 298 K and (b) <¾_* in 1 and 2 for CO? calculated from the 258, 273 and 298 K isotherms.

Figure 4 are graphs representing (a) (¾, for C0₂ of compound ! in. sites 1, II, and ill compared to the total «· as determined by the TSL model and CO; adsorption isotherms of compound I .for sites 1 (b), 11 (c), and II! (d) using the TSL model.

Figure 5 are graphs representing (a) COj selectivity over resulted from, the interaction with site I at 298 . at different total pressures in 0.5-2.0 bar range calculated using i^'AST for compound 1 and (b) experimental breakthrough test of traces ( .1000 ppm) CX^'h in mi ture with N? on compound 1.

Figures 6 A and 6B are graphs representing PXRD patterns of the as-synthesized, calculated and solvent-exchanged compounds 1-2, indicating the phase purity of as- synthesized and methanol-exchaiiged products.

Figure 7 is a graph representing PXRD patterns of the as-synthesized, calculated and solvent-exchanged compound 3, indicating the phase purity of as-synthesized and methanol-exehanged product . Figures 8A and 8B are graphs representing FXRD patterns of the as-synthesized, calculated and .solvent-exchanged compounds 4-5, indicating the phase parity of as- synthesized and solvent-exchanged products.

Figure 9A and 9B are graphs representing FXRD patterns of the as-synthesized, calculated and solvent-exchanged compounds 6-7, indicating the phase purity of as- synthesized and solvent-exchanged products.

Figure 1 is a graph representing PXRD patterns of the as-synthesized compounds 1 and 2 compared with the La, Eu and Yb fcu-MOF analogs.

Figure 1 1 is a graph representing PXRD patterns for compound 2 alter exposure to water, indicating a highly chemical stability in aqueous media.

Figures 12A and 12B are graphs representing TGA plots of the as-synthesized and methanol -exchanged compounds 1 -2.

Figure 13 are graphs representing TGA plots of the as-synthesized and meihanol- exchanged compound 3,

Figures 14A and 14B are graphs representing TGA plots of the as-synthesized and solvent-exchanged compounds 4-5.

Figures 15A and 1 SB are graphs representing TGA plots of the as-synthesized and solvent-exchanged compounds 6-7.

Figure .16 is a graph representing variable-temperature (VT) PXRD of compound 2, revealing the thermal stability up to 275 degree C.

Figure 7 is a ball-and-stick representation of compound 1 _> constructed from the assembly of I2-connected earboxylate tetfa¾oiaie-based molecular building blocks (MBBs) linked together via a Unear and heterofunctionai FTZB organic linker, to give a 3-per.iodi.c fcu-MOF with two types of polyhedral cages: i.e. tetrahedral. and octahedral.

Figure 18 is a ball-and-stick re resentation of compound 6, constructed from the assembly of 12-conneefed carboxyiaie-based MBBs linked together via a ditopic FBFDC organic linker, to give a 3-periodk fcu-MOF with two types of polyhedral cages.

Figure 19 is a synergetic effect representation of a C(¾ surrounded by an open metal site, uncoordinated nitrogen atoms of tetrazofate and polarizable fiuoro atom as well as hydroxo moieties.

Figure 20 are graphs representing Ar sorption isotherms collected at 7 K (a), pore s e distribution analysis (b) tor compound 1. Figure 21 are graphs representing l¾ sorption data for compound I ; (a) fully reversible ¾ isotherms collected at 77 and 87 and (b) (¾* for Hj calculated from the cojresponding isotherms.

Figure 22 are graphs representing C<¾ sorption data for compound 1 : (a) fully re versible VT COs Isotherms and (b) j¾t for COj calculated from the corresponding isotherms

Figure 23 are graphs representing Ar sorption, isotherms collected at 87 (a), pore size distribution analysis (b) for compound 2.

Figure 24 are graphs representing ¾ sorption date for data for compound 2; (a) fully reversible ¾ isotherms collected at 77 and 87 K and (b) Q_s( for % calculated from the corresponding isotherms.

Figure 25 are graphs representing CO? sorption data for compound 2: (a) fully reversible VT C.X¾, isotherms and (h) Q_sl for CO? calculated from, the corresponding isotherms.

Figure 26 are graphs representing CO? adsorption isosters for compounds 1. (a) and Z (b), confirming the accuracy of the O_a determined from VT C€½ adsorption isotherms as evidenced by the linearity in the isosters.

Figure 27 is a graph representing Q_si for€<¼ of compound 2 in sites !, II and II compared to the total {¾■ as determined by the TSL model,

Figures 28A-28C are graphs representing€€¾ adsorption isotherms of compound

2 for sites Ϊ, II. and ΪΪΪ using the TSL model

Figure 29 are graphs representing Ar sorption isother s collected at 87 K (a), pore size distribution analysis (b) for compound 3.

Figure 30 are graphs representing i¾ sorption, data for data for compound 3; (a) fully reversible % isotherms collected at 77 and 87 K and (b) J¾ for Ha calculated from the corresponding isotherms.

Figure 3.1 are graphs representing COj sorption data for compound .1: (a) fully reversible VT C<¾ isotherms and 0>) Q_® for CO¾ calculated from the corresponding isotherms.

Figure 32 is a graph representing ^!'^'F NMR spectrum of compound 3 digested in

HQ and DMSO, showing the presence of the modulator, 2-flnorobenzoic acid, and thus resulting in a reduced pore volume compared to the theoretical SCXRl) data (i.e. 0.39 vs 0.55 cnr^* g^"J). Figure 33 are graphs representing Ar sorption isotherms collected at 87 K (a), pore size distribution analysis (h) for compound 4.

Figure 34 are graphs representing ¾ sorption data for compound 4: (a) fully reversible ¾ isotherms collected at 77 and 87 K and (b) <¾. ibr Efe calculated from the corresponding isotherms.

Figure 35 are graphs representing CO? sorption, data for compound 4: (a) fully reversible VT C(¾ isotherms and (b) for CC½ calculated from the corresponding isotherms.

Figure 36 are graphs representing Ar sorption isotherms collected at 87 (a) and pore ize distribution analysis (b) for compound 5.

Figure 37 are graphs representing % sorption data for compound 5: (a) folly reversible Ih isotherms collected at 77 and 87 . and (¾_f for ih calculated from the corresponding isotherms.

Figure 38 are graphs representing C⁽¾ sorption data for compound.5: (a) fully reversible VT C(¾ isotherms and (b) Q _t for CO2 calculated from, the corresponding isotherms

Figure 39 are graphs representing Ar sorption isotherms collected at 87 K (a), pore size distribution analysis (b) ibr compound ii

Figure 40 are graphs represen ting ¾ sorption data ibr compound 6: (a) fully reversible ¾ isotherms collected at 77 and 87 . and (b) Q_M for ¾ calculated, from the corresponding isotherms.

Figure 41 are graphs representing CO₂ sorption data for compound. 6: (a) fully reversible VT C<¾ isotherms and (b) (¾, for CX¾ calculated from the corresponding isotherms.

Figure 42 are graphs representing Ar sorption isotherms collected at 87 K (a), pore size distribution analysis (b) ibr compound 7.

Figure 43 are graphs representing ¾ sorption, data for compound 7: (a) fully reversible i¾ isotherms collected at 77 and.87 K and (h) for i¾ calculated from the corresponding isotherms.

Figure 44 are graphs representing€<¾ sorption data for compound 7: (a) fully reversible VT CO? isotherms and (b) <¾ for€<¾ calculated from the corresponding isotherms.

Figure 45 are graphs representing€€ adsorption isosters tor compounds 4 (a) and 5 (fo). Figure 46 are graphs representing COj adsorption isosiers for compounds 3 (a) and 6 (b).

Figure 47 are graphs representing <¾_; for€<½ of compounds 3 (a) and 6 (b) in sites 1 and II compared to the total {¾ as determined by the DSL model.

Figure 48 are graphs representing€£¾ adsorption isotherms of compound 3 for sites Ϊ and 11 using the DSL model.

Figure 49 are graphs representing CC¾ adsorption isotherms of compound 6 for sites ί and 11 using the DSL model

Figure 50 is a schematic diagram representing the ubotherm gravimetric- dens iroe trie apparatus.

Figures 1A-51F are graphs representing excess high-pressure sorption isotherms for compound 1: ¾ CO?, CI¾, Na and Oj, The adsorption and desorption branches are represented as solid and open symbols, respectively.

Figure 52A-52F are graphs representing excess high-pressure sorption isotherms for compound 2: ¾_> C<¾, CR*_> z and <¾. The adsorption and desorption branches are represented as solid and open symbols, respectively.

Figures 53A and 53B are graphs representing water vapor sorption isotherms collected at 298 for compound 1 (top) and compound 2 (bottom) with adsorption (solid symbols) and desorption (open symbols) points, showing that both materials are tolerant to water. Note that the last desorption point corresponds to the coordinated water molecules in each material, i.e.. 5.50 water per Tb6 cluster and 5.76 water per Y6 cluster.

Figure 54 is a graph representing C<½ adsorption kinetics curve for compound 2 at 0.2 bar and 298 (collected during adsorption measurements).

Figure 55 are graphs representing CX¾ selectivity over ^"h½ resulted from the interaction with site I at 298 K at different total pressures in 0.5-2 barrange calculated using lAST for compound I.

Figure 56 is a graph representing experimental breakthrough test of traces (1 000 ppm) C(¾ in mixture with ]"½ on compound 1.

Figure 57 is a graph representing CC over N?. selectivity for compound. 1. and 2 calculated using !AST for CO_?/N¾: 10/90 gas mixture at 298 ,

Figure 58 is a collection of images representing SEM image for compound I (top), showing the uniform polyhedral morphology of fhe crystals and the optical images for compound 3 with different sizes due to varying the ethanoi concentration during synthesis (bottom). DETAILED DESCRIPTION

A metal- organic framework^' composition can have a face centered cubic (feu) structure composed of metal ions and bidentate h^'gands. The metal ions and bidetitate Hgands for molecular building blocks thai further form the fca structure.

The molecular building block (MBB) approach has recently emerged as a powerful strategy for the design and construction of solid-state materials. See, e.g., Stein et al_> Science 1 93, 259, 1558-1564; Ferey, G, J. Solid State Chem. 2000, 152, 37-48; Eddaoudi et al. Science 2002, 295, 469-472; Kitagaws et al, Angew. Chem. int. Ed. 2004, 43, 2334-2375; Mouiton et at, Chem. Rev. 2001 , 301 , 1629- 1.658; Eddaoudi et ai , Ace. Chem, Res. 2001, 34, 319-330; and U.S. Pat. No. 6,624,31 8 (each of which is incorporated by reference herein in its entirety). The molecular building block joins or otherwise associates with other molecular building blocks to form supramoiecuiar structures. The raoleeiilar building block can. be a 1.2-coanected molecular building block. The I2-connected molecular building block can have 12 sites for ligand attachment to neighboring structures.

The metal ions can form a metal ion component of the composition. The metal ion can be an. electron rich metal ion. For example, the metal ion can be a RE metal ion, tor example, a !anihanide elements, such as an ion of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy; Flo, Er, Tm, Yb, Lu, or Y. In certain circumstances, the metal ion is terbium or yttrium, e.g., Tb^:i o Y^:'.

The bidentate ligand can form, a bidentate ligand component of the composition. The bidentate ligand has two anionic binding groups. The two anionic binding groups, point awa from each other. Specifically, the two anionic binding groups can be oriented 180 degrees from each other. The bidentate ligand can have the structure:

A l— L- -A2 (I) in formula (1), each. A 3 can. be carboxyl, tetrazolyi, sulfony!, or phosphoryi;

in formula (I), each A2 can be carboxyl, teirazolyl, sulfonyl, or phosphoryi;

In preferred embodiments, A 1 and A2 are each, independently, carboxyl or ietra oiyl. Irs formula (I), L ean be a divalent aryl heteroaryi, carhoeyciyL o heterocydyL In preferred embodiments, L ears be a 3- to 14 membered divalent monocyclic

he erocyclyL a 3- to 14 membered divalent aryl, or a 3- o 14 embered divalent heteroaryL la preferred embodiments, L is substituted with 1 , 2, 3, or 4 halo or halomethyl groups. For example, L can be an. ortho substituted iluoro phenyiene, naphthylene or diphenylene group.

The term "aryl" refers to monocyclic, bicyclic or tricyclic aromatic hydrocarbon groups having from 6 to 14 carbon atoms in the ring -portion. In one embodiment, the term aryl refers to monocyclic and bicyclic aromatic hydrocarbon groups having from 6 to 10 carbon atoms. Representative examples of aryl groups include phenyl, naphihyi, fluorenyh and anthraeeny

The term "ary l" also refers to a bicyclic or tricyclic group in which at least one ring is aromatic and is rosed to one or two non-aromatic hydrocarbon ring(s). Nonlimiilng examples include tetrahydronaphthalene, dihydronap^'hthalenyl and indanyl

As used herein, the term "heterocycly refers to a saturated or unsaturated, non- aromatic monocyclic, bicyclic or tricyclic ring system which has from 3- to 15-ring members at least one of which is a heteroatom, and up to 10 of which may be heteroatoms, wherein the heteroatoms are independently selected, from 0„ S and N, and wherein and S can be optionally oxidized to various oxidation states. In one embodiment, a

heieroeyelyl is a 3-8-membered monocyclic, in another embodiment, a heterocyclyl is a 6~^'12-membered bicyclic. In yet another embodiment, a heterocyclycyl is a 10- 15- menibered tricyclic ring system. The heterocyelyl group can be attached at a heteroatom or a carbon atom. Heterocyolyls include fused or bridged ring systems. The term

''.heieroeyeiy)" encompasses heterocyeloalky.1 groups. The term "heteroeycloalky refers to completely saturated monocyclic, bicyclic or tricyclic heterocyelyl comprising 3- 15 ring members, at least one of which is a heteroatom, and up to 10 of which may be heteroatoms, wherein the heteroatoms are independently selected from O, S and N, and wherein N and S can be optionally oxidized to various oxidation states. Examples of faetetocyclyls include dihydrofuranyl, [1 ,3]dioxoiane, 1,4-dioxaae, 1,4-difhiane, piperazinyh 1,3-dioxoiane, inudazolidirsyl, irnklazoSinyL pyrrolidine, dihydropyran, oxat oSane, dithioiane, 1,3-dioxane, .1 ,3-dithiany.l oxatbi.anyl, thiomorpholinyl, oxiranyl, aziridinyl. oxetanyf azetidiny!, tetrahydrofuranyl, pyrrolidinyl. tetrahydropyranyl, piperidinyl, morpholinyl, piperazinyi, azepinyl, oxapinyl oxazepinyl and diazepinyl. The term, "spireheterocycloalkyr as used herein, Is a heterocycioalkyl that has one ring atom in common with the group to which it is attached, Spiroheteroeydoalkyl groups may have from 3 to 15 ring members. In a preferred embodiment, die

spiroheterocyeloalkyl has from 3 to 8 ring atoms selected from carbon, nitrogen, sulfur and oxygen and is .monocyclic.

As used herein, the term "heteroaryl" refers to a 5-14 raembered monocyclic-, bicyciic-, or tricyclk-ring system, having 1 to 10 heteroatoms independently selected from ^' _» O or S, wherein N and S can be optionally oxidized to various oxidation states, and wherein at least one ring in the ring system is aromatic, in one embodiment, the heteroaryl is monocyclic and has 5 or 6 ri ng members. Examples of monocyclic heteroaryl groups include pyrid l, thienyi, fu anyl, pyrroiyl, pyrazolyi, imidazoyL, oxazolyl, isoxazoiyi, ihiazolyl, .isoti.riaz.oiyi, tr.iazol.yl, oxadiazolyl, thiadiazolyl and ieirazoivf In. another embodiment the heteroaryl is bicyciic and has from 8 to 10 ring members. Examples of bkyeSic heteroaryl groups include indolyl, benzo&ranyl, quioolyf isoquinolyi indazolyi, indolinyk isotndolyi, indolmnyL, benzamida¾olyl, qiunolinyl, 5 ,7,8 eirahyd.roquino!.ine and 6 7~dmydro-5H-pym}io[3,2~d]pyrimid e.

As used herein, the term "carbocyclyi" refers to saturated or partially unsaturated (but not aromatic) monocyclic, bicyciic or tricyclic hydrocarbon groups of 3- 14 carbon atoms, preferably 3-9, or more preferably 3-8 carbon atoms. Carbocyciyls include fused or bridged ring systems. The term "carbocyclyi' ' encompasses cycloalkyl groups. The term "cycloalkyl" refers to completely saturated monocyclic, bicyciic or tricyclic hydrocarbon groups of 3 - 12 carbon atoms, preferably 3-9, or more preferably 3-8 carbon atoms. Exemplary monocyclic carbocyclyi groups include, but are not limited to, cyciopropyl, cyclobutyl, eyelopentyi, eyc.lopenten.yl, cyclohexyl or eyelo.besen.yl, Exemplary bicyciic carbocyclyi. groups include hornyL deeahydronaphthyi,

cyelo[2J .l ]hexyl, bicyelo[2.2.i]heptyi, bieyclo[2.2J]heptenyl, 6,6- dimethy1bicyclo[3.1. Ijheptyl, 2,6,6-i.rir.ueihylbieyei.o[3.1. Ijheptyl, or bieyelo[2,2.2]oetyi. Exemplary tricyclic carbocyclyi groups include adamantyl.

As used herein, the term "halocycloalkyl" refers to a cycloalkyl, as defined herein, that is substituted. by one or more halo groups as defined herein. Preferably the halocycloalkyl can be monohatocycioalkyl, dihaloeycloalkyi or polyhalocycloalkyl including perha!oeye!aalkyi. A monohaiocyeloalkyl can have one iodo, bromo, chio.ro or tluofo substituea Dihalocycloalkyl and polyhalocycloalkyl groups can be substituted with two or more of the same halo atoms or a combination of different halo groups. The terra "aryP also refers to a bieyeKc or tricyclic group in which at least one ring is aromatic and is fused, to one or two .non-aromatic hydrocarbon ring(s). Nonlimitmg examples include tetra ydronapbthalene, dihydronaphtfaalenyl and indanyt

The term "aryialk P refers to an alfcyl group substituted with a aryl group, Representative examples of arylalkyi groups include, for example, benzyl, pieot.yk and the like.

The terra "phenylene" refers to a divalent phenyl.

The molecular building block can include bridging iigands, such as, for example, oxy, hydroxy!, suiihydryl, or amino groups.

in the synthesis of the molecular building blocks, the molecular building block can have an overall ionic charge. Thus the molecular building block can be an anion or a cation and have one or more corresponding cou.nie.nous, such as. for example, 11^" , Li^*, Na\ K.\ Mg/ Ca^{' '} , S/ . ammonium (including monoalkyl, dialkyl. irialkyl or tetraalkylaikyi ammonium}, or one or F, CT, Br\ Γ, CIO^", CIO , CIO/, CIO/, Off, NO/, NO/, 50/\ SO ; P0 ^3", CO$ borate (including monoalkyl, dialkyl irialkyl or tetraalky!a!ky! borate) or and organic eounterions such as acetate or Inflate.

The A I and A2 groups are oriented at 180 degrees from each other. For example, when L is arylene, Ai and A2 are in a " a a" or substantially "para" relative position, in a pheay!ene structure, I and A2 are at posi tions 1 and 4 on the ring; in a hiphenylene structure, A 1 and A2 are at positions 4 and 4^*.

The method of making a MOF composition, cau include contacting a metal ion component with a bidentate ligand component having two anionic binding groups. A salt of the metal .ion can be dissolved in a solvent and combined with the bidentate ligand. Optionally, other salts can. be added to provide othe counter ions in the final structure, The material is then crystallized from the combined solution. The presence of a.

hydrophobic group in the bidentate ligand, for example, a fluoro group ortho to the binding group, contributes to formation, of the desired fcu structure. The bidentate ligand having a hydrophobic group can be present in a catalytic amount during formation of the final MOF.

A series of feu-MOFs based on RE metals and linear fl uorinated «o»-fl uorinated, homo- hetero-functional Iigands can be targeted and synthesized. This particular feu- MOF platform was selected due to its uni ue structural, characteristics combined with the ability/potential to dictate and regulate its chemical propert ies (e.g., tuning of the electron-rich rare-earth metal ions and high localised charge density, a property arising from the proximal positioning of polarizing tetrazolate moieties and fluoro-groups that decorate th exposed inner surfaces of the confined conical cav ies). These features permitted a systematic gas sorption study to evaluate/elucidate the effects of distinctive parameters on COj- OF sorption energetics. It shows the importance of the synergistic effect of exposed open metal sites and proximal highly localized charge density toward materials with enhanced C(¾ sorption energetics.

in recent years, there has been a strong scientific drive to minimize greenhouse gas emissions especially€<¾. See, for example, Cms, S. Science 2009, 325, 1599, which is incorporated by reference in its entirety. The release of CO> from fine gas and the automobile industry are the major contributors, and myriad efforts are underway to economically separate and capture the effluent C€½. See, for example, The Center for Climate and Energy Solutions (C2ES), Reducing Greenhouse Gas Emissions from U.S. Transportation, 201 1 , Arlington; Sumida, K..; Rogow, D, I,.; Mason, J. A.; McDonald, T. M; Bloch, E. D.; . Herns, Z. R,; Bae, T.-H.; Long, J. . Chem. Rev. 2-012, 112, 724.781, Vaidhyanathan, R. Iremonger, S. S.; Shiraizu, G. . II; Boyd, P. G.; Alavi, S.; Woo, T. K. Science 201 1, 330, 650-653, each of which is incorporated by reference in its entirety. Highly porous sorhent materials have emerged as a plausible solution, and considerable efforts have been put forth to develop suitable materials. An optimal adsorbent for CO; separation should. In addition to high adsorption uptake and suitable kinetics, exhibit high affinity toward C<¾ to be translated itvto high interaction, which in turns plays a critical role in determining the adsorption selectivity and the energy required to release C(¼ during the regeneration step. Accordingly, the ideal isosteric heat of adsorption (<¾} should permit reversible physical adsorplion-desorption operation in a pressure or vacuum swing adsorption. (PSA. or VSA) process (i.e., C(¾- so.rbenf interactions are neither too strong nor too weak).

OFs, a relatively new class of porous materials, appear well-poised to address th CO;- challenge due to their mild synthesis conditions, relatively high thermal stability, large pore volumes, potentially exposed inner surface with high localized charge density, and readily programmable and modular construction (i.e., a given structure with the desired net topology ; runctionahxab!e isoreticular structures) from predesigned molecular building blocks (MBBs), See, for example, flobson, A. J. Chem. Sac., Dalton Trans. 2090, 3735-3744; Percy, G. J. Solid Siate Chem,, 1MHI 152, 37-48; Eddaoudi, M.; Moler, D.B.; Li H.; Chen, B.; Reineke, T.M.; O'KeefXe, M.; YaghL O.M, dec Chem, Res. 2001 , 34, 319-330; Chun, H.; Dybtsev, D. ; Kim, H.; Kim, K. Chem. Eur. J. 2005, II, 3521-3529; Metal-Organic Frameworks: Design and Application; MacGiliivray, L, R., Ed.; Wifey-VCH: Weinheim, Germany, 2Mi> Kiiagawa, S.; Kitaura, PL; Noro, S.-I. Angew. Chem., int. Ed. 2884, 43, 2334-2375; Ferey, G. Chem. -See. Rev. 2«08, 37, 191- 214, each of which is incorporated by reference in its entirety. As such, considerable effort has been dedicated to ascertaining the ideal COj-MOF interactions/energetics-, but minimal systematic studies of finely-toned MOFs have been reported. See, for example, Sutnida, ,; Rogow, D. L.; Mason, J. A.; McDonald, T. M.; Bloch, E, D.; Eerm, Z. R.; Bae, T.~B.^* Long, J. R. Chem. Rev. 2012, 112. 724-7 1 ; Vaidiryanainan, R.; ircmonger, S. S,; Shimizu, G. K. !:L; Boyd, P. G; AJavi, S.; Woo, T, K. Science 2010, 330, 650-653, each of which is incorporated by reference in its entirety.

Development and isolation of novel MBBs can facilitate the rational construction of targeted functional MOFs. See, for example, Li a, Y.; Eubank, J. F.; Cairns, A. I;

Eckert, J. ; ravtsov, V, Ch.; Luebke, R.; Eddaoodi, M. Angew. Chem., Int. Ed 2887, 46, 3278-3283, each of which is incorporated by reference in its entirety. The discovery of novel modular and rigid inorganic MBBs and establishing reaction conditions that permit to generate a specific inorganic BB consistently in situ can be a vital

crtterion prereqiiisite for the prospective design and rational construction of desired MOFs.

With the aim to construct porous MOFs with high localised charge density, a potential attribute to promote/enhance the CX¾ sorption energetics, porous MOFs with high localized charge density, a potential attribute to promote/enhance the CO* sorption energetics, can be prepared based on meta -ligand directed assembly of electron-rich RE metal ions and no.n-centrosymmelric hetero-functional Iigands containing carboxylase and terazolate moieties. Hcxasuciear RE~based (Tly Y^{' r}) MBBs, generated in. situ, to construct a series of 1.2-eonneeted MOFs can possess face centered cubic (feu) topology. The MBBs are bridged in a linear fashion through an assortment of iluoro and or tetra oiate funetionaiked organic Iigands, as outlined in Scheme i . Systematic gas sorption studies on these materials have elucidated the effects of distinctive parameters on COj-MOF sorption energetics.

Scfeeme 1. Representation of the organic linkers present in com ounds 1-7.

EXAMPLES

A series of fca- OFs based on rare-earth naetals and functional igands

Reactions are based on solvot ermal reactions between RE metal, salts (RE - Y, Tb) and asymmetric hetero-functionai ditopic linkers (e.g., 2-ffnoro-4-(i H-tetrazo I- yl)benzoic acid (H₂FFZB) and 4-< lH-tetrazol~5^«yi)benzoic acid (H₂TZB» In various solvent mixtures. Reaction between R TZ8 and Tb(N0₃)r5¾0 in an NJ - diraethyifonT5amide 5 F)/ethanol/c !orobenzene solution yielded transparent polyhedral crystals, formulated by single -cry si ai x-ray diffraction (SCXRD) studies a

!{C¾)₃NH₂l2rr ₆(^ OHMFTZB)_{;(H₂0},] · (I).

Compound I crystallizes in the cubic space group Fm~3m, In the crystal structure oil, each 1V~ metal ion i surrounded by four OH groups, four oxygen and/or nitrogen atoms from statistically disordered carboxylase groups and/or tetra¾olate rings from four independent FTZB"^" .Uganda, leaving the ninth coordination site occupied by a water .molecule (Figure ^'!.)· The adjacent Tb ions are bridged via ij-OH and deprotonated carhoxylate and/or tetrazolate groups in a. bis-xnonodentate fashion to give a

MBB. Each hexanuciear MBB is bridged through FTZB^2" to produce a 3-periodie MOF. Stractural/topologicsl analysis of Hie resulting crystal structure reve ls that ί is a MOF with the face-centered cubic (feu) topology (i.e., an fea-MOF) constructed from the bridged hexanuclear clusters, ¾_&( ί_ί- Η)<₅(()₂θ-)ί_!( ₄0}_ί}] MBBs, where the carbon atoms of the coordinated carboxyiate and teirazolate moieties, acting as points of extension, coincide with the cuboctahedron. vertex figure of the quasireguiar fee net, the only 12-connected edge transitive net. Edge transitive nets possess only one kind of edge, and are ideal targets in crystal chemistry. See, for example, Friedrichs, 0. 0«; 0¾effe, M.; Yaghi, O. M. Acta Ctysia!iogr. 2093, A59, 22-27: Friedrichs, O. ϋ,; O'keeffe, M.; Yaghi, O. M. Acki Cryskii gr, 2003, A5 515-525; Robinson, S. A. K.; Mempm, M.-V. L.; Cams, A. 1,; Hobnan, . T. J. Am. Chem, Soc, 201.1., J33, 1634-1637; asciocchi .; Galls, S. Colombo, V,; Maspcro, A.; Palmisaao, G,; Seyyedi, B.; Lamberti, C; Bordiga, S. j. Am. Chem. Soc. 2010, 132, 7902-7904, , each of which is incorporated by reference in its entirety. Replacement of the metal salt with Y( ⁽¾);r6H₂0 in the same reaction mixture, resulted in the analogous fcu-MOF, (CHs NHsJa Y^- OH)a(FTZB)_!,(HjO)_<i.]-(H:50)52 (2). Similar reaction conditions for the non-fluoriaated linker, !¾TZB, resulted in clear solutions. Howe ver, introduction of a fluormated modulator, 2-flaorobenzoie acid, has permitted the successful construction of the desired TZB-based isostr uctural fen-MOF,

(3). as determined by SCXRD studies. Under the present reaction conditions, a fiuoro- substnuent located in the alpha (a) position relative to the carboxyiate moiety can be necessary for the formation of the 12-eonneeted RE-based MBB. The present hexanuclear clusters, based oa mixed carboxylates and tetrazolates, are unprecedented., though a corresponding pure carboxyiate molecular cluster based on cerium recently appeared hi the open literature. See, for example, Mereaere, V.; Ako, A. .; Akhtar, M. .;

Lindemann, A.; Anson, C. E; Powell, A. K. tfelv, Chim. Ada 2009, 92, 2507-25.24; Das, It; Sarraa, R.; Baruah, I. B. norg. Chem. Comm. 2010, 13, 793-795, each of which is incorporated by reference in its entirety.

Occurrence of other analogous hexanuclear clusters in MOF chemistry is limited to a single Zf-based 12-eoordkate MBB, where isosiruetaral Zr^! -based fca-MOFs (e.g., UiO-66) based on Ζ¾(0} 0Η) ί0₂<;-)π] MBBs are linked together via linear homo- functional dicarboxylate ligands. See, for example, Cavka, J. FL; Jakobsen, S.; Oisbye, tJ.; Guillou, N.: Lamberti, C; Bordiga, S.; Lilierud, . P. J. Am. Chem. Soc. 2008, ISO, 13850-13851 ; Schaate, A.; Roy, P.; Godt, A.; Lippke, J,; Waltz, F.; Wiebcke, M. an Behrens, P. Chem, Eur. J. 2011, 17, 6643-665 L each of which is incorporated by reference in its entirety.

fc«~MOFs based on. RE metals can be constructed, and the [ E^C^-O^^OsC- MBB, RE Tb and Y can be consistently generated in situ. Such attributes combined with the fact that me feu net is the only edge transitive net for the assembly of 12-connected cuboctahedron building units, permit the practice of reticular chemistry par excellence, rational MOF design, and thus access to a new MOF platform based on the feu topology, where the metal ions and ligami functional groups and size to perform a .systematic stud on. the effect of the structural changes on CO;?-MOF energetics can be methodically modified,

The fctt-MOF structure encloses two polyhedral cages, i.e., octahedral and tetrahedrat with effective accessible diameters estimated to he, in. the case of compound 1, 145 and 9, 1 A (considering van der Waais radii), respectively. Access to the cages is permitted through shared triangular windows, ca. 5-6 A, which are of suitable size for the adsorption of small gas molecules, e.g., Ar, !-¾>„ CO?, etc. The corresponding solvent accessible tree volumes tor 1 and 2 were estimated to be 63.0% and 63.8%, respectively, by summing voxels more than 1 .2 A away from the framework using PLATON software. See, for example, Spek, A. L. Acta Crysialhgr. 1990, 46, c34, which is incorporated by reference in its entirety.

In order to achieve maximum and accurate sorption results, the phase purity of the porous material can first be verified. The phase purity of the balk crystalline materials for 1 and 2 was independently confirmed by similarities between the calculated and as- synthesized powder X>ray diffraction (PX D) patterns (Figures 6A and 6B). In addition, both compounds also show favorable water and thermal stability (Figures 2,. 1.1. and 16), which is an important parameter for potential practical deployment of porous MOFs in carbon capture applications.

Argon gas adsorption studies performed on the methanoi-exchanged samples show folly reversible type-! isotherms, representative of micro-porous materials (Figures 20 and 23). The apparent BET surface area and pore volume for 1 and 2 were estimated to be ! 220 m^{i !} and 0.51 cm^'* g", and Di O nf g ^! and 0.56 cm⁵ g^"', respectively.

In order to evaluate the performance of compounds Ϊ and 2, an initial ¾

adsorption study at lo pressure was performed. The I¾ adsorption uptake was assessed to he 1.96 and 2.19 wt% at 760 tort and 77 K (Figure 21 (a) and 824(a)), while Q_xt for ¾ was determined and estimated to be 8,7 and 92 kJ ηκ Γ^} at. zero coverage for ! and 2, respectively (Figures 21 (b) and 24(b)}.

To farther this study, the C<¾ sorption was investigated, and it was found that ! and 2 reversihiy adsorb a significant amount of COj under ambient conditions, Le., 3.5 o.rniol g^"5 (1.5.6 %) and 4.1 mrool g^'5 (18.1 %), respectively, at 298 K and 760 tarr (Figure 3(a)). Interestingly and in contest to most MOFs, a steep slope is observed in the low pressure region for both materials, a feature that is indicative of enhanced CQr^'MOF interactions. Indeed, the for CX calculated ftom the corresponding variable temperature adsorption isotherms was 58.1 and 46.2 ki mol^"1, for 1 and 2, respectively, at low loading (Figure 3(b)). In fact, these results are discerned as amongst the highest reported thus far for fully reversible CX¼ sorption on MOFs in the absence of any postsynthetic modification and/or surface area reduction. The accuracy of the Q_vt

determination was confirmed across the entire loading range by verifying the linearity of C<¾ adsorption isosters (Figure 26). At the exception of Mg-MOF-74, the CO_% uptake at low pressure (0.01 bar and 298 K) for 1 and 2 (Table 1 ) is the highest reported thus far for MOFs (including amme-functionalked MOFs) with relatively fast CO? adsorption kinetics (Figure 54).

Table J . CO? uptake in compounds 1 and 2 as compared to other MOFs reported in the literature.

Mg- OF-?4 ; Casfcey, 8. R.; Wgii«-Foy, A. Q; M w . A, I J Am. Chem Sac IMS, 1 , miiMiW i Mmm-Oa BT n; Mc n ld, ML: VA eutoo, D. M; Kr¾h»a, R.; Long, Ϊ. R. Cham. Set 2911,

In order to pinpoint and understand the different energetic levels associated with the unique CX¾ adsorption properties observed in 1 and 2, particularly at low pressures, we performed an in-depth g« analysis study using a multiple site Langrauir model (MSL). In tact, three energetic sites were clearly identified and derived from the best fit and convergence obtained when using the triple site Langrnuir model (Figure 27). The observed energies tor sites ! and III were found to be identical k I and- 2, ca. 60 and 25- 26 k. moi^"', respectively. The former energetic site can be attributed to the localized high concentration of charge density resultant front the mutual presence of both a fhroro substUuent and th nitrogen-rich ietrazolate moiety in proximal vicinity of the open metal si te, while she III is simply doe to the effect of pore filling. See, for example. Sumida, .; Rogow, D, L.; Mason, J. A.; McDonald, T. M,; Bloch, E. D,; Herm, Z, R.; Bae, ^'ΪΑΜ,; Long, L R. Chem. Rev. 2812, 112, 724-781 ; Lin, J.-B.; Zhang, i.-P.; Chen, X.-M. J. Am. Chem. Soc. 2010, 132_t 6654-6656; tin, Q.; Wo, T.; Zheng, S.-T.; Bu, X.; Feng, P. J, Am. Chem, Soc. 2012, 134, 784-787; Burd, S. IX; Ma, S. Q,; Perman, J. A.; Sikora, 8. 1.; Snurr, R. Q.; Thallapally, P. ..; Tian, J.; Wojtas, L.; Zaworotko, M J. J Am. Chem. Soc. 2012, 134, 3663-3666; Eueoke, R.; Eubank, .1. F.; Cairns, A. .?.; Be! abkhout, Y.; Wojtas, L,; Eddao di, M. Chem. Comrmm., 2012, 48, 1455-145?, each of which is incorporated by reference in its entirety. Differences arising from the choice of metal ion are evident in site II, where energetic levels of 47 and 35 ki moP were determined for compounds I and 2, respectively. The recorded {¾t is likely the average energy of these sites, while the total C0₂ uptake is the summation of adsorption isotherms for sites 1, 11 and ill (Figures 4B-4D and 28A-2SC). The presence of conical pockets (i.e., tripodal and quadrapodaS narrow size cavities), decorated with .fluoro moieties and tetraaolate groups, can create a high localized charge density and promote synergetic effects favorable for enhanced C<¾ sorption at low loadings. Using site I parameters for compound I, Ideal adsorbed solution theory (1AST; see Myers, A. L. & Praasniiz, j. M. A!ChE I 11 , 1965, 121-127, which is incorporated by reference in. its entirety) prediction of adsorption at various trace concentration of CO* (from 100 ppm to 1%) in a mixture with > , mimicking vacuum swing operational mode at various working pressures, revealed an exceptionally high adsorption selectivity (ca. 370) for CQi over Nj (Figure 5A). This finding was -further confirmed experimentally using a column breakthrough test with a€¾Φ½:0 4/ .99% mixture (Figure 57), showing an even higher selectivity (ca. ί 051 ).

The II 2 and CO , as well as other gas, sorption properties were further investigated at high pressure, it was found that at 77 . and 4(3 bar 1 and 2 store 3.9 and 4.4 w†% of¾, respectively, while for C<¾ 7.1 ramol g^*3 (31.2 %) arid 9.3 ramoi g^"5 ( 1.1 %) were adsorbed, respectively, at 298 . and 25 bar (Figures 5 IA-5I F and 52A-52F), Though these values are lower than those recorded for g-MOF- 4, they are among the highest COj uptakes per surface unit reported at 25 bar. Markedly, when, sites I are fully saturated at lower CC pressures, the less energetic sites (11 and Hi) dominate the€(¾ adsorption at moderately higher C(¾ concentration arid pressure as reflected by the relatively reduced C0j/N₂ selectivity to ca. 16 at 10% vs. 370 at 0.01%, as determined by (AST (Figure 58), The predominance of site Ϊ, the COs sorption high energetic site, can permit efficient C(¼ separation at intermediate (10%, flue gas) and high (30-50%, biogas) C<¾ concentration.

The successful isolation of reaction conditions that consistently permit the in situ generation

MBB„ and corresponding fcu-MOF platform, offer potential to assess the distinctive role of the flaoro substituent and teraxolate moiety on the adsorbate-MOF mteraetions. Accordingly, various

anaiogotts/isoretieuiar fcu-MOF s were targeted and synthesized, including other RE metal ions (e.g.. La^'"^', Eir and Yb^{J '}) (Figure 10) and diverse mono-/poly 1aorinated, hetero-Zhomo- functional, and extended Ugands.

In the first example, the organic Baker was expanded from ¾F1^'ZS to 3-fl«o.ro-4'- (2H etrazol-5-yi)biphenyl-4-carboxylie acid (H₂FTZBP) (Scheme 1) and reacted with Tb or Y nitrate salts to give the expected isoreticuiar compounds,

OH)₈(FrZBP),(¾0)_s]-s:(solvOTt) (4) or

OH FTZBP HjO.kj-xisolvent) (5), respectively. As expected, the analogous fluori saied dicaroo.xy.late linker. 3-fiiion>biphen.yl-4_s4^,-dicarboxyl.ate (FBPDC, Scheme I ), which is generated in situ via hydrolysis of4^,-cyano-3-<luorobiphenyl-4-carboxylk acid, and 3 ^,-difluorobipheny1"4_s4'-diearboxyiic acid (BVDFBPDC, Scheme 1) react with Tb to give the isoreticular analog of 1, denoted as (CHs^NH jslTbsOr

OFI)«(FBPDC ¾0)_&] ^(solvent) (6) and {(CH₃)₂NH₂]2{. b

OH)_s(DFBPDC)_¾Cri₂i¾] -.K(solver!|) (7). respectively. The CO; sorption properties were assessed for compounds 3-7, and, as expected. fc«-MOFs constructed from the elongated iluormated aeiero-t nciiooal ligand (i.e., 4 and 5) revealed a lower adsorption capacity and reduced (¾ values (36,7 and 27.2 kl mof ^!, respectively) compared to fee parent feu- MOF based on the shorter and conjugated F^'I^'ZS ligand. This study clearly supports that reducing the electronic density (by increasing the distance between the fhioro and teirazokie substituents; i.e., by not having both of them on the same phenyl ring) affords a weaker COs-framework affinity,, which is also directly reflected by the reduced CX¾ uptake. Likewise, 3, 6, and 7, f om TZB*\ FBPDC^2" and DFBPDC^2"Kgands, respectively, have less localized electronic charge density when compared to 1. based on the more polarized FTZB"^' ligand, and thus show reduced CO₂ adsorption uptakes and relatively lower Q_a values &r CO_∑ adsorption at Sow loading (39.1-46.6 vs 58.1 ki mot¹ for I). Additionally, MSL analysis performed on. the COj sorption data for 3 and 6 showed that the best fit and convergence was attained only when the dual site Langrauir was applied (Figure 48), suggesting the presence of merely two energetic adsorption sites instead of lite three energetic sites originally observed in the parent tetrazolate-based fcu- DFs (e.g., ί and 2).

Given the unique structural features of this RE-based fea-MOF platform, the following synergistic combination of effects is likely responsible for the notable CX¾ capacity and high affinity towards COj. These include (i) a high concentration of localized electron-rich vacant metal sites; (ii) the presence of polar groups (Le>, -F, -OH) and nitrogen-rich tetrazolate rings in a confined narrow space and at a proximal vicinity of the open metal sites, favoring rnuiii ali (multi-sites) interactions with a single COj molecule, allowing their interaction with€X > in a synergistic .fashion.

Reaction conditions that consistently permit the in situ generation of the R£¼(/t3* ΟΗ)κ{θ3€-)ή(Ν€-)_ή]: and RE^w OHMOsC-)^] hexanucfear MBBs were isolated and successfully employed for the construction of a series of robust and water stable .12- connected RE-based fce-MOFs based on fluorinated non-fluortnated and hetero-Zliomo- ikoctional iigands. Trivalent RE metal clusters can be assembled into highly-connected MOFs, in this case fea-MOFs, displaying diverse adsorption energetics toward CC¾. The utilisation of polarised iigands containing tetrazolate and iluoro moieties afforded enhanced sorption energetic and uptakes due to their unique special positioning, in a narrow proximal vicini ty of the open metal sites, offered by the unique fea-MOF

.structure. The high CO? affinity vs. N_; , particularly at low pressure, as well as the favorable tolerance to water and high thermal stability, -certainly renders 1 and 2 promising prospective adsorbents for low€<¾ concentration purification involving multicomponent gas adsorption. Studies are underway to further employ the newly isolated 12-conn.ected [[RE«{ j-OH)8{0₂C-)e( 4C-¾j and

MBBs for the construction of highly connected MOFs based on hetsro-Zhomo- Afunctional and tetraiunctional Iigands with the main objecti ve to increase the concentration per unit surface of the highly energetic sites for CC¼ sorption in a wide range- of pressures.

Examples

Materials and Methods. The organic iigands used in this study, i.e., 2-t!uoro^«4^« (lll-tetrazol-S-yl) benzoic acid (FhFTZB) and 4«{2Hte&¾zol«S«yI) benzoic acid C¾TZB). were synthesized from 4-cyaao-2-fiuorobenzoio acid and 4-cyaao e.azoie acid, respectively, with 67 and 74% yields using the Demko-Sharpiess method. ^w The organic ligaod 3-tluoj )-4'-(2H-tetta¾ol-5~yl)biphe«yl-4-carl5oxyIic acid (¾FI.Z8P) was synthesized from 4'-cyatto-3-ftuorob.iphenyl-4-cai¾ xyiic acid according to literature methods.⁵ The organic iigand 3,3^,-dil1uorobip!ieByi-4,4'-dicar oxylic acid (iijDFBPDC) was synthesized from the following Suzuki homocoupiing reaction; A mixture of 4- horono~2-i1uorohenzok acid (2.0 g, 10 mmol), potassium carbonate (1.5 g) and 5% unreduced palladium on carbon (2.0 g) in ethanol (20 ml) was heated at 85 °C for 24 h under nitrogen. The mixture was filtered through a Ceiite pad, and the solvent was evaporated. Five milliliters of 1.0 sodium hydroxide were added to dissolve the solid, The solution was acidified by Ϊ.0 M HQ after filtering and extracted in ethyl acetate, dried over ajSO , and filtered, and the voiatiles were removed under reduced pressure to yield fljDFBPDC as a white crystalline solid (0.5 g, 36% yield). ^lH NMR (500 MH¾r, DMF-d?): 3 - 7,97 it J - 7.6 Hz, 2 H), 7,69 (q, J - 6.4 Hz, 2 H)» 7.3.1-7.39 (m, 2 H). Ail other reagents were obtained from commercial sources and used without further purification,

Fourier-transform infrared (FT-iR) spectra (400O-600 cm ^!) were collected in the solid state on a N.icolet 700 FT-iR spectrometer. The peak intensities are described in each of the spectra as very strong (vs), strong is), medium (m), weak (w), broad (br) and shoulder (s.h).

Powder X-ray diffraction (PX.RD) measurements were performed on a

PANalytical X' Pert PRO MPD X-ray diffracto eter at 45 kV, 40 mA for Cu Κ ( - I ..5418 A) equipped with a variaMe-temperature stage, with a scan speed of 2'Vmin. The sample was held at the designated temperatures for at least 10 mm between each scan. High resolution dynamic hermogravimetrie analysis (TGA) were performed under a continuous _:> flow and recorded on a TA instruments hi-res TGA Q500

thermogravimetric analyzer with a heating rate of 5 °C per xninute. Low pressure gas sorption measurements were performed on a full automated Autosorb-lC gas sorption analyzer (Qoantachrome instruments). High pressure gas sorption studies were performed on a magnetic suspension balance marketed by Rubotherm (Germany) .The SEM image was recorded on a Quanta 600 PEG scanning electron microscope at 30 kV, and the optical image were taken on a C.MM-55 microscope. Water vapor sorption measurements were conducted at room temperature on a VTI--SA symmetrical vapor sorption analyzer.

Synthesis ofCompoitn&s. Synthesis of Tb-FTZS-MOF (J ).

B-TTZB ( 13,6 Big, 0.0653 mraol), Tb{N0₃)r5H,0 (18,9 mg, 0.0435 mmoi), DMF (1.0 ml), QH₅GH (0.5 ml), aad chiorobensene (0.5 BIL) were combmed in a 20 ml scintillation vial, sealed and heated to 1 15 °C for 72 h and cooled to room

temperature. The colorless polyhedral crystals were collected and air dried. FT R

(4000-600 cm^"5 ): 3379 (br), 1651 (s), 161 1 (m), 1388 (vs), 1251 (w), 1097 (m), 905 (m). 797 (m), 746 (m), 656 (rn).

Synthesis of Y-FTZB-MOF (2). H₂FTZB ( 13.6 m , 0.0653 mmoi),

Y( O?)r6¾0 (1 .7 nig, 0.0435 mmoi), DMF (1.0 mL)₅ C¾Fl₅OH (0.5 mL), and chlorobcBzene (0,5 mL) were combined in a 20 ml scintillation viaL sealed a»d were heated to 115 °C for 72 h. The colorless polyhedral crystals were collected and air-dried. FT-i^' (4000-600 cm^"'}: 3385 (br), 1.658 (s), 1612 (m), 1.391 (vs), 1204 (w), 1090 (si 904 (s), 800 (m), 750 (ml 656 (ml

Synthesis of Tb-TZB-MOF (3). HjTZB (1.6.5 mg, 0.087 mmoi), l¾(N¾)y5H₃<) (18.9 mg_s 0.0435 mmoi), 2-iIuorobenzoie acid (48.7 mg, 0.348 mmoi), DMF ( L0 mL), CJHJOH (1.5 ml) were combined i« a 10 mL microwave tube, sealed and heated to 115 ^¾C for ^"2 h and cooled to room temperature. The colorless polyhedral crystals were collected and air-dried. FT-IR (4000-600 cm^"1}: 3358 (br), 1656 ( ), 1603 (vs), 1659 (s), 1497 (w), .1397 (vs), 1281 (w), 1255 (w), 1 176 (w), 1099 (s)_t 1058 (w), 101 1 (m), 878 (w), 840 iw), 801 (m), 7 1 is), 701 (w), 663 (w).

Synthesis of Tb-FTZBP- OF (4). H₂FTZBP (24.7 mg, 0.087 mmoi),

Tb(N0₃b-5I:½0 (18.9 mg, 0.0435 mmoi), DMF (1.0 ml), Q¾OH (0.5 mL), and chlorobenzene (0.5 mL) were combined in a 2 mL scintillation vial, sealed and heated to 115 °C for 72 h and cooled to room temperature. The brown polyhedral crystals were collected and air-dried. FT-IR (4000-600 cm^"!): 3358 (br), 1650 (vs), 1610 (m), 141 1 (m), 1385 (m), 1254 (w>, 1099 (s), 1009 (w), 905 (w), 843 (w), 796 (m), 765 (m), 660 (w).

Synthesis of Y-FTZBP-MOF (5). H₂FTZBP (24.7 mg, 0.08? mmoi),

Y(N0₃)₃ ^■ 6¾0 ( 1 .8 mg, 0.0435 mmoi), DMF (.1.0 mL),€₂¾OB (0.5 mL), and chloroben ene (0.5 mL) were combined irs a 20 ml, sc ntilladoB vial, sealed and heated to 1 .15 *C for 72 h and cooled to room temperature. The brown polyhedral crystals were collected and air-dried. FT-IR (4000-600 cm^"'): 3363 (br), 1657 (vs), 1611 (v), 1499 (m). 14.12 (m). 1385 (s), 1251 (w), 1097 (s), 1058 (w), 1007 ( 906 (w), 845 (w), 796 (m)_t 765 cm), 660 (w).

Synthesis of b-FBFDC- OF (6). 4 ;yaBO"3~tIaorobip¾e:ny!4-carboxylk acid (41.9 mg, 0.174 mmol), Tb(NO_s)r5H₂0 (37.8 mg, 0,087 mmol), DMF (1.5 mL),

CjHjOH (0,5 mL), and chlorobenzene (0.5 mL) were combined i a 20 mL scmtillation vial, sealed and heated to 1 15 °C for 72 h and cooled to .room temperature. The colorless polyhedral crystals were collected and air-dried, FT-iR (4000-600 cm^"'5): 3350 (or), 1655 (w), 1 584 (vs_.), 1528 (w), 1382 (vs), 1 188 ( ), 1109 (m), 1014 (w), 907 (ffi), 846 (m), 779 (s), 697 (w), 662 (w).

Synthesis of Tb-DFBFDC~MOF (7). HjDFBFDC 08.2 mg, 0.065 rnmol),

Tb( 0₃)r5H₂0 (18,9 mg, 0.0435 mmoi), DMF (1 , mL), C2H5OH (0.5 mL), and chkiroheozene (0,5 mL) were combined m a 20 mL scmtillation vial, sealed a»d heated to 115 °C for 60 h and cooled to room temperature. The colorless polyhedral crystals were collected and air-dried. FT-iR (4000-600 cm^"5): 3338 (br). 1651. (w), 1582 (vs), 1493 (w), 1528 (w), 1385 (vs), 1253 ( )« 1209 (w), 1102 (m)_? 1061 (w), 954 <w), 861 <m), 843 (ra), 784 (m), 695 (m).

Low-Press tire Gas Adsorption Measurements

Low pressure gas adsorption studies were conducted on a felly automated micropore gas analyzer Autosorb-IC (Quantachrome Instruments) at relative pressures up to 1 atm. The cryogenic temperature was controlled using liquid nitrogen and argon baths at 77 K and 87 , respectively. The bath temperature for the CCh sorption measurements was controlled using a recirculating bat containing an ethylene glycol/HjO mixture. The apparent surface areas were determined from the argon adsorption isotherms collected at 87 by applying the Branauer immeit-Teller (BET) and Langmuir models. Pore size analyses were performed using a cylindrical/spherical NLDFT pore model system by assuming an oxidie (zeolitic} surface. The determination of the isosterk heats of adsorption (Q_$) for ¾ and C<¼ was estimated by applying the Ciausins-Clapeyron expressioa using the ¾ sorption isotherms measured at 77 and 87 and the C(¾ isotherms measured at 258, 273 and 298 unless otherwise noted,

Homogenous microcr stailine samples of compounds !~7 were activated by washing the as-synthes&ed crystals with 3 x 20 nil, of DMF followed by solvent exchange in methanol (Compounds 1-3) or ethanol (compounds 4-7) for 3 days. The solution was refreshed several times daily during this time period, In a typical experiment, 30 to 40 mg of each activated sample was transferred (dry) to a 6-mm large bulb glass sample eel! aad firstly evacuated at room temperature using a turbo molecular vacuum pump am! then gradually heated to 16CFC for 1, 2, 3 and 7, 12CFC for 4-5 {incteasmg at a rate of PC/roin), held for 16 h and cooled to room temperature. Data are presented in Table 2.

Table 2. Low ressure sorption data summary for compounds ί-7. α.<ινφί.«>ιηί BET P. V. H. CO, ⁽ -.-, fer

<:·»·^' g ') Uptake" (ki ssel '} O,

(«'('!<,! (fcJT m...l ^! i ϊ 1220 1510 ft.51 1 .90 8.69-5.39 7.53, S.S6 5SJ.-2S.0 asvd. 3.S4

2 1310 U 40 0.56 2. Ϊ9 S.53, 6.46 46.1 -24.0 aad 4. S 2

3 5145 1 .47 S .45-5 5? 5 ,.><·= 4.55 40.6-23 S a«d 2.50

4 2200 2560 0 > o ^• 53 :^ 1 .2.75 56.7-20.3 sad I 64

5 24 If) 2820 ; .:· : S.52-4,9 1 4.0 L 2.81 27.2^,4.9 5

:;!::! 1 .59

6 5.940 2.330 0.7$ 1.57 6. -5.06 3.50, .2.40 ^•9. i 53.5

.:Γ.ύ 1.37

7 1SS4 2161 0.72 13» 7.05-4 «9 3.91, 2.63 41.6-20.7

;i»d t .56

* u iiiks? at 77 K and 760 torr; * ~ CCK uptake .wfcjasttissd at 25% 273 and 29S mp i eiy CO₂ Adsorption <¾. Analysis on. Compounds 1 and 2 Using Multiple-site

Laagrmtir model (MSL)

Equation for MSL: n^:::: n»cm*btp/l +bip + ¾_¾w^*½ -*·½?+ .... + i*bip I+b$> The best fi t and convergence were obtained with the triple site Langmuir (TSL) model The parameters extracted from the best TSL fit were used to recalculate the adsorption isotherms and the evolution of the Q^ fm each energetic site (site 1, site H aad site .III) using the C!ausius-Clapeyron. equation. Table $2. Triple s te La«amuir parameters (Compound D

Temperature / K

Parameters

273 298

Adsorption 0.33956 0.27756 0.2691 Site I

t> 147.49445 4SU5585 5.50219

Adsorption 0.37026 0,40104 0.42S27 Site 11

/> > 4.91024 1.5S224 0.22432

Adsorption 10.86539 11 JS52 15.24316 Site III

0.01703 0.00865 0.00231

Ta&fte S3, Triple sits Lang uir parameters (Compound 2}

Temperamre / .

Parameters

258 273 298

0.39195 0,35252

Adsorption 0.29521.

Site 1 i 259.98806 80.03201 2X96898

0.52812 0..5334 0.62601

Adsorption

Site II bz 9.75852 2.64722 0.83725

ί 1.82402 12.0789 12.99557

Adsorption 0.01696 0.00859 0.00326

S Iil

High-Pressure Gas Adsorption Measurements

Adsorption equilibrium measurements for the pure gases were performed using a Rubotherm graviraetric-densimetric apparatus (Bochum, Germaxjy) (Figure 50), composed mainly of a magnetic suspension balance (MSB) and a aetwork of valves, mass flo wmeters and temperature and pressure sensors. The MSB overcomes the disadvantages of other commercially available gravimetric instruments by separating the sensitive mlerobalanee from the sample and the measuring atmosphere and is able to perform adsorption measurements acros a wide pressure range, Le, 0 to 200 bar. Moreover, the adsorption temperature can be controlled in the range of 77 K to 423 K, in a typical adsorption experiment, the adsorbent is precisely weighed ami placed m a basket suspended by a permanent magnet through an electromagnet. The ceil in which the basket is housed is then closed ami vacuum or high pressure is applied. The gravimetric method allows the direct measurement of the reduced gas adsorbed amount Q. Correction for the buoyancy effect is required to determine the excess adsorbed amount using equation l_s where V^^s and V_ss refer to the volume of the adsorbent and the volume of the suspension system, respectively. These volumes are determined, using the helium isotherm, method fay assuming that helium penetrates in ail open pores of the materials without being adsorbed. The density of the gas is determined using efprop equation of state (EOS) database and checked experimentally using a voluine-calibrated titanium cylinder. By weighing this calibrated volume in the gas atmosphere, the local density of th gas is also determined. Simultaneous measurement of adsorption capacity and gas phase density as a function of pressure and temperature is therefore possible. The excess uptake is the only experimentally accessible quantity and there is no reliable experimental method to determine the absolu te uptake. For this reason, only the excess amounts are considered in this work,

Ω - m_:._w /¾,. ί ί ^_;,,_κί - F { i)

The pressure is measured using two Drocks high pressure transmitters ranging from 0.5 to 34 bar and Ϊ to 200 bar, respectively, and one low pressure transmitter ranging from 0 to 1 bar. Prior to each adsorption experiment, about 1 0 mg to 300 mg sample is outgassed at 433 K at a residual pressure 10 mba.r. The temperature during adsorption measurements is held constant by using a thermosiated circulating fluid.

Figure 55 shows the selectivity of CX¾ over 1 at 298 , calculated (using I AST)[c] from levels of a few ppm to I %, assuming CO? interaction with compound 1 are completely governed by adsorption on site I. The selectivity was calculated assuming different total pressures tor the mixtures (i.e., 0.5, I and 2 bar). The purpose of the total pressure variation, is to .mimic vacuum swing adsorption (VSA) regeneration mode conditions supposing 0.2, 0,5 and 1 ba as the working adsorption pressure aod vacuum as the desorption pressure. As was expected, the CO* selectivity over 1% was high (ea. 370) in the domain when interaction with site Ϊ are the most dominant Prediction of CO2/N2 selecti vity at variable total pressures from 0.5 bar and up to 2 bar showed that the CO_{2 2} separation decreased by increasing the total pressure and concentration due to the quick saturation of most of energetics sites (site I) available. Therefore a way to maintain high selectivity is to increase the density of site 1. In. order to confirm thk finding,

breakthrough adsorption experiments were carried out using a mixture containing

1000 pprn of CO; at 298 K and a total pressure of 1 bar. The purpose of using such low concentration is lo explore experimentally the separation performance of the compound .1 where the adsorption is .mostly governed by the most energetic site (site J).

interestingly, the breakthrough test shows that the C ¾ was retained in the bed for ca. 5250 s while ₂ breakthrough occurred almost after few second (Figure 56), The gas uptake for CCh and N₂ at breakthrough was 0.262 and 0.249 ramo! g. Therefore, the COj/N? selectivity was exceptionally high (ca. 1051} exceeding the predicted selectivity using lAST, This finding is extremely important as it shows that materials with high density of adsorption site 3 will certainly lead to suitable separation agents for€€½ removal .from gas streams with even higher C<¾ concentration (.10-30%) in order to produce useful commodities such as C¾ <¾ and ¾> wit higher efficiency. Ongoing work is focusing on. the design of new OFs with such attributes.

Single Crystal X-ray Crystallography. Single-crystal X-ray diffraction data were collected using a ruker-AXS SMART-APEX2 CCD diffractoraeter (Cu Κα, X = 1.54178 A) for compounds 1 and 2, Bruker X8 PROSPECTOR APBX2 CCD (Cu Κα, λ - 1. 4178 A) for compounds 3 and 5 -7, and Oxford Supernova Atlas CCD (Mo « ^::: 0,71073 A) or compound 4. Indexing was performed using APEX2 (Difference Vectors method).16 Data integration and. reduction were^•performed using SaintPlos 6.01. Broker SAINT, Data Reduction Software; Bruker AXS, Inc.: Madison, Wl, 2009, which is incorporated by reference in its entirety. Absorption correction was performed by mulliscao method implemented in SADAB^'S. Sfae rick, G. M. SADABS, Program .fo Empirical

Absorption Correction; University ofGotringen: Oottingen, Germany, 2008, which is incorporated by reference in its entirety. Space groups were determined using XP EP implemented in APBX2. Bruker AP.BX2; Bruker AXS, Inc.: Madison, Wl, 2 10, which is incorporated by reference in its entirety. Structures were solved using SHELXS- 7 (direct methods) and refined using SHBLXL-97 ( l-matrix least-squares on F2) contained, in APEX216 and WmGX vl .70.01 programs packages. See, for example, (a) Farrugia, L. I. App!. Crystsdlogr. 1 99, 32, 837-838. and Sheldriek, G. M. SHELXL-97, Program for the Refinement of Crystal; University of Gottmgen; Gottingen, Germany, 1997, (c) Sheldriek, G. M. Acta Crystailogr. 1990, A46, 467-473. (d) Sheldriek, G, , Acta CrystaHogr. 2008, A64, 1 12-122, each of which is incorporated by reference in its entirety, CrysAlk Pro package was used to process diffraction images for compound 4, CrysAlis Pro; Oxford Diffraction: Abingdon, U.K., 2009, which k incorporated by reference in its entirety. For all compounds the iigand moiety was disordered and atoms were refined using geometry .restraints. Restraints were also used to refine anisotropic displacement parameters of disordered atoms. Disordered cations and solvent molecules were refined isotropically. Relatively high residual electron density observed in a μ~ΟΗ position (leading to very small value of ihermal parameters for μ-ϋίί oxygen) are most likely attributed to "electron transfer (...) directed from <:/~orbitais to the oxygen 2p orbitals", which is observed hi yttrium-oxide clusters. Pramann, A.; Nakamura, Y.; Nakijama, A.; Kaya, K. I. Phys. Chem. A 2001, 105, 7534-7540, which is incorporated by reference In its entirety. Hydrogen atoms were placed in geometrically calculated positions and included in the .refinement process using riding model with isotropic ihermal parameters: ¾»(H) - 1.2tJeq(-OH, "CM).

The crystal of compound 7 was twinned, twinning law -Q.66 ).33/0.66]

[0.66/- 0,66/0.33] [0.33/0.66/0.66]. Two reciprocal lattices have been identified using XPREP (APEX2); diffraction data have been integrated using SAINT and

scale 'corrected using TWINABS. Shekirick, G. M. TW^'f ABS; Broker AXS, inc.; ^'Madison, Wl, 2002, which is incorporated by reference in its entirety. Refinement has been carried using B LF 5 style reflection data containing reflection from both domains (BASF ^» 0.12). Distance restraints have been used to refine disordered benzene rings.

Disordered atoms have been refined isotropically. For compounds 3-7, the contribution of heavily disordered solvent molecules was treated as diffuse using Squeeze procedure implemented hi Platon program. Spek, T, L. Acts Crysta!logr. 1 90, A.46, .194-20.1 , which is incorporated by .reference in. its entirety. Crystal data and refinement conditions are shown in Tables 3 S..

TaMe Crystal d¾fe and ¾¾n¾ct»t¾ rftfi a i½- eoropetaid Y-FT2B-MOF (2)

Rtei&akoii co e

Empirical ibnmda C_a¾F*N_¾€½Ys

Fon&ulst eght .2902.38

Wavelesgth 1.54178 A

Cm&! ¾ &ί&, s i e r Cubic, Fm-3m

s == 23.4365(4) A. alpha - 90 dsg. b - 2.5.4365(4) A bets ·-· 9 c - 23.4365( } A suiinsa - 90 feg

12875,0(4) A ^:?

Z. Cakalatsd dsn-sty 4. !.49SMa¾v^?

Ahwrpioa eoeSkiajit 4.52? sua; ⁵

F(OOO) 5096

Crystal slz« 0,10x0.10x0.10 mm

Theta j sa e for dats collect »a 5.34 to 0.3.48

Litems: isKlce* ~27 -h -25. 8 -% - 7, ~17 =4 - 10

5335/ 75 CR(uii)- 0,0313]

Coa¾ *fea*«s to slse - 63.48 97.0 %

S¾»s-&3Spinc i iVoin squiva!ems as. l mm, toa*ram.to» 0.6603 A 06003

Rei ssserst method Full-matrix k&s-si atss <m F^"

Data rc-stokifrs / parameters 575 69 / 88

GooAeSS~«£-i¾ Oil F² 1.052

FioaJ i fi e* [l 2«asBil)] Ri 0.0395, ¼¾^»0.H 60

R indices (all data) 0.0414, > ¾-0.HS3

I.S49 a»d -0.597*. A^"3

I Table ..7. Crystal data asd structure refinement for compound IZB-MOF (3)

Id ntification code 3

Empirical formula < :,·$ H 5₂ zi <½ I s

Formula weigh 2826.43

lemperatare 100(2)

Wavelength 1.54178 A

Crystal s stem, space group i ^'abi.. Fm~3m

Unit ceil dimensions - 23.5195(5) A alpha - 90 deg.

23.5195(5) A beta -90 deg. c * 23.5 i 95(5) A gamma * 90 deg.

Volume 13010.2(5) A ^s

2, Calculated density 4. 1.439 M n

Absorption ctKsfficieat 16.428 mm^{' s}

F(000) 5336

Crystal size OJOx .lOxO.I mm

Thera range for data collection 5.32 to 67.93 deg.

Limiting indices -26 -h -22 -20 -k<-18. -22<H -2?

Reflecti ns collected unique 10330/ 624 l^' (int)- 0,0380]

Completeness So thefts ~ 65.9 99.0 %

Absorption correction. Semi-empirical from equivalents

Max, aad mm. tuttismission 0.2904 and 0,2904

Refinement method Full-matrix least-squares on F^;

Dat ! restraints parameters 624 / i / 64

Goodness-of-ist on F^" 1.086

Final R indices p 2sigma(i)j R, - 0.0340, - 0.1028

R. indices (all data) R: -0.0343, - 0.1031

Largest dill peak and hole Li 61 and -0.493 e. Λ '

Ideatifiation code 5

Harp-irical i raraia C^H^FeNiAsY*

Fomyrte weight 2450.88

Temper te© 100(2} K

aveieagth 15 178 A

Crvstsl system, s ce group Cubic. P -3m

a 29,447(3) A alpha === 90 d g. h - 29.447(3) A beta - 90 deg.

- 29.447(3) A samsB - 90 des.

Vhsms 25535(4) A⁵

2, Calculated daosit 4, 0.638 Mg¾r

A sorpion coeSkieirf 2.074 ami¹

F( Ofi) 4840

Crystal Hi 0.20 x 0.20 x 0,20 mar

Theta rssnge for data collector* 6.01 to 65.64 deg.

Limiting iadiees -3 -¾ -2 , -3 -k<-34. >23<^~i<^~33

Reiectioos collect**! / oaiq»e 20849⁽1148 iRiiat}- 0.09S]

Completeness to ikeia ~ 65.64 98.3 %

Absorption correction Serai-eas iricai from quialents

Max. aad m tmmn . 0.6818 mid 0.6818

R&finsm&m. ethod l-matrix 2east~ecjuare& on F^J

Data resrairits / arameters 1148 ( 71 / 89

Goodaes.4.-of-i¾ on F^'; 1059

Final ^"R indices I>2¾gms(i)| ¾ - 0.0337. w¾ - 0.1010

iadiees (all data) & - 0,0340, ¾9?>- 0.101 β

Lmmsi diil v&sk. and hole 0.675 ;UKI -0,283 e.. ⁵

l..^^dl ^¾k¾ndho]e 0,839 and -0. 16 e. A^"5

T&bk It . Crystal d ta sad siuct re refine ent for eompouad Tb-1> BFDC- 0F (?) i e«u4icark>n code 7

Emp irieai .formula (-,_sib,S^;-< lh,

Formula weight 2962.6

Te perature 1002) K.

1.54178 A

Crystal system, s ac goup Cubic, :m-3n

Unk cell dimensions if - 27.4756(7} A aioha - 90 dee,

6 -27.4756(7} A bei»- 0dsg.

e™ 27.4756(7) A gam a™ 90 deg.

lume 2074 i . (0) A ^:

¾ Calculated density 4, 0,949 Mwm

Absorption coefficient 10.332 mm¹

Fi CiO) 5624

Crysal si¾e 0,15 s 0.15 s 0.15 mm

Theta range for data ci.41eeiion 4,55 f 67.93 cleg.

iJmitmg indices -23<-h<-31 _s -32 ^« <;-29, ~2S -K-31

Reflections collected / unique 5524/ 524 (R(im)- 0.004)1

C mpleeness to i eta ^« 66.60 98.7 %

Absorption corection Semi-empirical from equivalents

Max. sad mm. transmission 0.3063 and 0.3063

Refinement m thod Fulknmtrix least-squares on F"

Data estrains parameters 5524/4/38

Gooduess-oMt on F' 1.051

Final R indices [l 2sigma >| - 0.0732, wR, ^» 0.2048

indices (ail dats)

Largest άϊϊΐ peak arid hole 1. 37 and -!. 39e, A^~:? j

A number of em odiment of the mvention have been described. Nevertheless, tt will be understood that various modifications- may be made without departing from the spirit and scope of the .mvention. Other embodiments are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1 , A metal organic framework composition comprising:

a metal ion component; and

a bidentate ligand component having two anionic binding groups, wherem the two anionic binding groups are oriented i 80 degrees ftom each other;

wherein the metal ion component and the bidentate ligand component associate to form a face-centered cubic network.

2. The metal organic fraoiework composition of claim I , wherein the metal ion component includes a rare earth metal ion.

3. The metal organic framework composition of claim L wherein the .rate earth metal, ion is La, Ce, Pr, Nd. Sra, Eu. CM. Dy_s Ho, Br, Tm, Yb, Lo, Tb or Y

4, The metal organic frame work composition of claim I , wherein the two anionic binding groups are the same,

5, The metal organic framework composition of claim L wherein the two anionic binding groups are different.

6. The metal organic framework composition of claim !, wherein each of the anionic binding groups, independently, is earboxylate or tetraxolate.

7. The metal organic framework composition of claim I , wherein the two anionic binding groups are linked by an aromatic group.

8, The metal organic framework composition of claim L wherein the aromatic group includes a hydrophobic group.

9. The metal organic framework composition, of claim 8, wherein hydrophobic group is a f!uoro group. ί 0, The me al organic framework composition of claim ! , wherein the metal ion component and the hidemate ligand form a 12-conn.ected molecular building block.

1.1. A method of making a metal organic framework composition comprising: contacting a metal sort component with a bidentate li and component having two anionic binding groups, wherein the two anionic binding groups are oriented 1 SO degrees from each other;

wherein the metal ion component and the bidentate ligand component associate to form a face-centered cubic network.

12, The method of clai m 11, wherein the bidentate ligand includes a hydrophobic group.

13; The method of claim 12, wherein hydrophobic group is a rJuoro group.

14. The method of claim 1 i , wherein the metal ion component includes a rare earth metal ion,

! 5. The method of claim 11 , wherein the rare earth metal ion is La, Ce, P.r, Nd, Sm, En, Gd, Dv, Ho, Er, Tm, Yb, Lu. Tb or Y.

16. The method of claim 1 1 , wherein the two anionic binding groups are the same,

17. The method of claim 1 ! , wherein the two anionic binding groups are different.

18. The method claim 11. wherein each of the anionic binding groups, independently, is carboxylate or tetrazelate.

1 . The method of claim 1 ί , wherein the two anionic binding gronps are linked by an aromatic group. 20 , The method of claim I I , wherein t he metal ion component and the bide aie iigand form a 1.2-eo.ra>ected molecular building block.