METAL-ORGANIC FRAMEWORKS FOR GAS ADSORPTION

20220056064 · 2022-02-24

    Inventors

    Cpc classification

    International classification

    Abstract

    Disclosed are metal organic frameworks (MOFs) for adsorbing guest species, methods for the separation of gases using the MOFs, and systems comprising the MOFs. The MOFs comprise a plurality of secondary building units (SBUs), each SBU comprising a repeating unit of one metal cation connected to another metal cation via a first moiety of an organic linker; a layer of connected adjacent SBUs in which a second moiety of the linker in a first SBU is connected to a metal cation of an adjacent SBU, and wherein adjacent layers are connected to each other via linker-to-linker bonding interactions

    Claims

    1. A method for the separation of a first species from a mixture, comprising contacting the mixture with a sorbent comprising a metal organic framework (MOF), wherein the MOF comprises: a plurality of secondary building units (SBUs), each SBU comprising a repeating unit of one metal cation connected to another metal cation via a first moiety of an organic linker; a layer of connected adjacent SBUs in which a second moiety of the linker in a first SBU is connected to a metal cation of an adjacent SBU, and wherein adjacent layers are connected to each other via linker-to-linker bonding interactions; and wherein the first species is selected from carbon dioxide, carbon disulfide, nitrous oxide, water, hydrogen sulfide, hydrogen cyanide, functionalised C1-3 hydrocarbons, and a combination thereof.

    2. The method of claim 1, wherein the the linker has the structure of Formula (I) or a salt or anion thereof: ##STR00005## wherein: A is selected from —COOR.sup.1, —C(O)R.sup.1, —CONR.sup.1.sub.2, —C(NR.sup.1)(NR.sup.1.sub.2), —NO.sub.2, —OC(O)NR.sup.1.sub.2, —OC(O)OR.sup.1, 'OC(O)R.sup.1, —N(R.sup.1)C(O)OR.sup.1, —N(R.sup.1)C(O)R.sup.1, —R.sup.2CO.sub.2R.sup.1, —R.sup.2C(NR.sup.1)(NR.sup.1.sub.2), —R.sup.2CONR.sup.1.sub.2, —R.sup.2NO.sub.2, —R.sup.2OC(O)NR.sup.1.sub.2, —R.sup.2OC(O)OR.sup.1, —R.sup.2OC(O)R.sup.1, —R.sup.2NR.sup.1C(O)OR.sup.1, —R.sup.2N(R.sup.1)C(O)R.sup.1, —SO.sub.3R.sup.1, —R.sup.2SO.sub.3R.sup.1, —R.sup.2OC(S)NR.sup.1.sub.2, —R.sup.2SC(O)NR.sup.1.sub.2, —SO.sub.2R.sup.1, —R.sup.2SO.sub.2R.sup.1, —R.sup.2(OR.sup.1).sub.2, —R.sup.2(OR.sup.1)(COOR.sup.1), —R.sup.2(OR.sup.1)(NR.sup.1.sub.2), —R.sup.2(OR.sup.1)(SR.sup.1), —R.sup.2(COOR.sup.1).sub.2, —R.sup.2(NR.sup.1.sub.2)(COOR.sup.1), —R.sup.2(SR.sup.1)(COOR.sup.1), —R.sup.2(SR.sup.1).sub.2, —R.sup.2(NR.sup.1.sub.2)(SR.sup.1), —R.sup.2(NR.sup.1.sub.2).sub.2, —R.sup.2(O).sub.2, —R.sup.2(OR.sup.1)(O), —R.sup.2(O)(COOR.sup.1), —R.sup.2(O)(NR.sup.1.sub.2), —R.sup.2(O)(SR.sup.1); B is selected from —OR.sup.1, —R.sup.2OR.sup.1, —NR.sup.1.sub.2, —R.sup.2NR.sup.1.sub.2, —SR.sup.1, R.sup.2SR.sup.1, —COOR.sup.1, —R.sup.2CO.sub.2R.sup.1, —CONR.sup.1.sub.2, —R.sup.2CONR.sup.1.sub.2; C is selected from —OR.sup.1, —R.sup.2OR.sup.1, —NR.sub.2, —R.sup.2NR.sup.1.sub.2, —COOR.sup.1, —C(O)R.sup.1, —CONR.sup.1.sub.2, —C(NR.sup.1)(NR.sup.1.sub.2), —NO.sub.2, —OC(O)NR.sup.1.sub.2, —OC(O)OR.sup.1, —OC(O)R.sup.1, —N(R.sup.1)C(O)OR.sup.1, —N(R.sup.1)C(O)R.sup.1, —R.sup.2CO.sub.2R.sup.1, —R.sup.2C(NR.sup.1)(NR.sup.1.sub.2), —R.sup.2CONR.sup.1.sub.2, —R.sup.2NO.sub.2, —R.sup.2OC(O)NR.sup.1.sub.2, —R.sup.2OC(O)OR.sup.1, —R.sup.2OC(O)R.sup.1, —R.sup.2NR.sup.1C(O)OR.sup.1, —R.sup.2N(R.sup.1)C(O)R.sup.1, —SO.sub.3R.sup.1, —R.sup.2SO.sub.3R.sup.1, —R.sup.2OC(S)NR.sup.1.sub.2, —R.sup.2SC(O)NR.sup.1.sub.2, —SO.sub.2R.sup.1, —R.sup.2SO.sub.2R.sup.1, —R.sup.2(OR.sup.1).sub.2, —R.sup.2(OR.sup.1)(COOR.sup.1), —R.sup.2(OR.sup.1)(NR.sup.1.sub.2), —R.sup.2(OR.sup.1)(SR.sup.1), —R.sup.2(COOR.sup.1).sub.2, —R.sup.2(NR.sup.1.sub.2)(COOR.sup.1), —R.sup.2(SR.sup.1)(COOR.sup.1), —R.sup.2(SR.sup.1).sub.2, —R.sup.2(NR.sup.1.sub.2)(SR.sup.1), —R.sup.2(NR.sup.1.sub.2).sub.2, —R.sup.2(O).sub.2, —R.sup.2(OR.sup.1)(O), —R.sup.2(O)(COOR.sup.1), —R.sup.2(O)(NR.sup.1.sub.2), —R.sup.2(O)(SR.sup.1); R.sup.1 is independently selected from hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl, aralkyl, heteroaryl, and wherein R.sup.1 is optionally substituted with one or more of alkyl, halogen, haloalkyl, amino, alkylamino, alkoxy, hydroxyl, alkylhydroxyl, thiol, alkylthiol, cyano and nitro; R.sup.2 is independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, alkyoxy, aryl, aralkyl, and heteroaryl, and wherein R.sup.2 is optionally substituted with one or more of alkyl, halogen, haloalkyl, amino, alkylamino, alkoxy, hydroxyl, alkylhydroxy, thiol, alkylthiol, cyano and nitro; A, B and C are bonded to core Q, wherein Q is selected from the group consisting of aryl, heteroaryl, heterocycloalkyl and cycloalkyl groups, and wherein Q is optionally further substituted with one or more substituents selected from hydroxy, halogen, haloalkyl, haloalkoxy, amino, nitro, cyano, aminoalkyl, dialkylamino, aminoalkenyl, alkyloxy, alkenyloxy, alkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heterocycloalkyl, cycloalkyl, carboxy, carboxyalkyl, carboxyalkenyl, thiol, alkylthio, arylthio, aralkylthio, nitro or cyano, each of which may be optionally further substituted.

    3. The method of claim 2, wherein the organic linker has the structure of Formula (II) or a salt or anion thereof: ##STR00006## wherein: A, B and C are as defined for Formula (I); and R3, R4 and R5 are independently selected from the group consisting of hydrogen, hydroxy, halogen, haloalkyl, haloalkoxy, amino, nitro, cyano, aminoalkyl, dialkylamino, aminoalkenyl, alkyloxy, alkenyloxy, alkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heterocycloalkyl, cycloalkyl, carboxy, carboxyalkyl, carboxyalkenyl, thiol, alkylthio, arylthio, aralkylthio, nitro or cyano, each of which may be optionally further substituted.

    4. The method of any one of the preceding claims, wherein the SBU has a formula of [ML.sub.2].sub.n, wherein M is the metal cation,L is the organic linker and n is an integer greater than 0.

    5. The method of any one of the preceding claims, wherein the metal is selected from Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Sc.sup.3+, Sc.sup.2+, Sc.sup.+, Y.sup.3+, Y.sup.2+, Y.sup.+, Ti.sup.4+, Ti.sup.3+, Ti.sup.2+, Zr.sup.4+, Zr.sup.3+, Zr.sup.2+, Hf.sup.4+, Hf.sup.3+, V.sup.5+, V.sup.4+, V.sup.3+, V.sup.2+, Nb.sup.5+, Nb.sup.4+, Nb.sup.3+, Nb.sup.2+, Ta.sup.5+, Ta.sup.4+, Ta.sup.3+, Ta.sup.2+, Cr.sup.6+, Cr.sup.5+, Cr.sup.4+, Cr.sup.3+, Cr.sup.2+, Cr.sup.+, Cr, Mo.sup.6+, Mo.sup.5+, Mo.sup.4+, Mo.sup.3+, Mo.sup.2+, Mo.sup.+, Mo, W.sup.6+, W.sup.5+, W.sup.4+, W.sup.3+, W.sup.2+, W.sup.+, W, Mn.sup.7+, Mn.sup.6+, Mn.sup.5+, Mn.sup.4+, Mn.sup.3+, Mn.sup.2+, Mn.sup.+, Re.sup.+, Re.sup.6+, Re.sup.5+, Re.sup.4+, Re.sup.3+, Re.sup.2+, Re.sup.+, Re, Fe.sup.6+, Fe.sup.4+, Fe.sup.3+, Fe.sup.2+, Fe.sup.+, Fe, Ru.sup.8+, Ru.sup.7+, Ru.sup.6+, Ru.sup.4+, Ru.sup.3+, Ru.sup.2+, Os.sup.8+, Os.sup.6+, Os.sup.5+, Os.sup.3+, Os.sup.2+, Os.sup.+, Os, Co.sup.5+, Co.sup.4+, Co.sup.3+, Co.sup.2+, Co.sup.+, Rh.sup.6+, Rh.sup.5+, Rh.sup.4+, Rh.sup.3+, Rh.sup.2+, Rh.sup.+, Ir.sup.6+, Ir.sup.5+, Ir.sup.4+, Ir.sup.3+, Ir.sup.2+, Ir.sup.+, Ir, Ni.sup.3+, Ni.sup.2+, Ni.sup.+, Ni, Pd.sup.6+, Pd.sup.4+, Pd.sup.2+, Pd.sup.+, Pd, Pt.sup.6+, Pt.sup.5+, Pt.sup.4+, Pt.sup.3+, Pt.sup.2+, Pt.sup.+, Cu.sup.4+, Cu.sup.3+, Cu.sup.2+, Cu.sup.+, Ag.sup.3+, Ag.sup.2+, Ag.sup.+, Au.sup.5+, Au.sup.4+, Au.sup.3+, Au.sup.2+, Au.sup.+, Zn.sup.2+, Zn.sup.+, Zn, Cd.sup.2+, Cd.sup.+, Hg.sup.4+, Hg.sup.2+, Hg.sup.+, B.sup.3+, B.sup.3+, B.sup.+, Al.sup.3+, Al.sup.2+, Al.sup.+, Ga.sup.3+, Ga.sup.2+, Ga.sup.+, In.sup.3+, In.sup.2+, In.sup.1+, Tl.sup.3+, Tl.sup.+, Si.sup.4+, Si.sup.3+, Si.sup.2+, Si.sup.+, Ge.sup.4+, Ge.sup.3+, Ge.sup.2+, Ge.sup.+, Ge, Sn.sup.4+, Sn.sup.2+, Pb.sup.4+, Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.2+, As.sup.+, Sb.sup.5+, Sb.sup.3+, Bi.sup.5+, Bi.sup.3+, Te.sup.6+, Te.sup.5+, Te.sup.4+, Te.sup.2+, La.sup.3+, La.sup.2+, Ce.sup.4+, Ce.sup.3+, Ce.sup.2+, Pr.sup.4+, Pr.sup.3+, Pr.sup.2+, Nd.sup.3+, Nd.sup.2+, Sm.sup.3+, Sm.sup.2+, Eu.sup.3+, Eu.sup.2+, Gd.sup.3+, Gd.sup.2+, Gd.sup.+, Tb.sup.4+, Tb.sup.3+, Tb.sup.2+, Tb.sup.+, Db.sup.3+, Db.sup.2+, Ho.sup.3+, Er.sup.3+, Tm.sup.4+, Tm.sup.3+, Yb.sup.3+, Yb.sup.2+, Lu.sup.3+, and any combination thereof.

    6. The method of any one of the preceding claims, wherein the metal is M.sup.2+.

    7. The method of any one of the preceding claims, wherein the metal cation has an octahedral coordination geometry.

    8. The method of any one of the preceding claims, wherein A is selected from —COOR.sup.1 and —R.sup.2CO.sub.2R.sup.1.

    9. The method of any one of the preceding claims, wherein B is selected from —NR.sup.1.sub.2 and —R.sup.2NR.sup.1.sub.2.

    10. The method of any one of the preceding claims, wherein C is selected from —COOR.sup.1 and —R.sup.2CO.sub.2R.sup.1.

    11. The method of any one of the preceding claims, wherein the linker to linker bonding interactions are non-covalent.

    12. The method of any one of the preceding claims, wherein the linker to linker bonding interactions comprise hydrogen bonding interactions.

    13. The method of any one of the preceding claims, wherein the linker to linker bonding interactions are between group C of the linker.

    14. The method of any one of the preceding claims, wherein the linker to linker bonding interactions comprise carboxyl-carboxyl bonding interactions.

    15. The method of any one of the preceding claims, wherein the mixture comprises anaesthetic gas, refrigerant or coolant gas, air, natural gas, liquefied petroleum gas, coal seam gas, syngas, or combinations thereof.

    16. The method of any one of the preceding claims, wherein the mixture comprises any of the following, or a combination thereof: hydrogen sulphide (H.sub.2S), oxygen (O.sub.2), nitrogen (N.sub.2), hydrogen (H.sub.2), helium, neon, argon, krypton, xenon, radon, ozone (O.sub.3), carbon monoxide (CO), nitric oxide (NO), and nitrogen dioxide (NO.sub.2), hydrocarbons (functionalised or non-functionalised), or derivatives thereof.

    17. The method of any one of the preceding claims, wherein the first species is carbon dioxide.

    18. The method of any one of the preceding claims, wherein the sorbent further comprises a material selected from polymeric materials, membranes, resins, biomolecules, clays, ceramics, carbon, inorganic oxides, and a combination thereof.

    19. A system for separating a first species from a mixture comprising: a chamber having an inlet adapted to direct the mixture into the chamber; and a sorbent comprising a metal organic framework (MOF) positioned within the chamber, wherein the MOF comprises: a plurality of secondary building units (SBUs), each SBU comprising a repeating unit of one metal cation connected to another metal cation via a first moiety of an organic linker; a layer of connected adjacent SBUs in which a second moiety of the organic linker in a first SBU is connected to a metal cation of an adjacent SBU, and wherein adjacent layers are connected to each other via linker-to-linker bonding interactions; and wherein the first species is selected from carbon dioxide, carbon disulfide, nitrous oxide, water, hydrogen sulfide, hydrogen cyanide, functionalised C1-3 hydrocarbons, and a combination thereof.

    20. The system of claim 19, wherein the the linker has the structure of Formula (I) or a salt or anion thereof: ##STR00007## wherein: A is selected from —COOR.sup.1, —C(O)R.sup.1, —CONR.sup.1.sub.2, —C(NR.sup.1)(NR.sup.1.sub.2), —NO.sub.2, —OC(O)NR.sup.1.sub.2, —OC(O)OR.sup.1, 'OC(O)R.sup.1, —N(R.sup.1)C(O)OR.sup.1, —N(R.sup.1)C(O)R.sup.1, —R.sup.2CO.sub.2R.sup.1, —R.sup.2C(NR.sup.1)(NR.sup.1.sub.2), —R.sup.2CONR.sup.1.sub.2, —R.sup.2NO.sub.2, —R.sup.2OC(O)NR.sup.1.sub.2, —R.sup.2OC(O)OR.sup.1, —R.sup.2OC(O)R.sup.1, —R.sup.2NR.sup.1C(O)OR.sup.1, —R.sup.2N(R.sup.1)C(O)R.sup.1, —SO.sub.3R.sup.1, —R.sup.2SO.sub.3R.sup.1, —R.sup.2OC(S)NR.sup.1.sub.2, —R.sup.2SC(O)NR.sup.1.sub.2, —SO.sub.2R.sup.1, —R.sup.2SO.sub.2R.sup.1, —R.sup.2(OR.sup.1).sub.2, —R.sup.2(OR.sup.1)(COOR.sup.1), —R.sup.2(OR.sup.1)(NR.sup.1.sub.2), —R.sup.2(OR.sup.1)(SR.sup.1), —R.sup.2(COOR.sup.1).sub.2, —R.sup.2(NR.sup.1.sub.2)(COOR.sup.1), —R.sup.2(SR.sup.1)(COOR.sup.1), —R.sup.2(SR.sup.1).sub.2, —R.sup.2(NR.sup.1.sub.2)(SR.sup.1), —R.sup.2(NR.sup.1.sub.2).sub.2, —R.sup.2(O).sub.2, —R.sup.2(OR.sup.1)(O), —R.sup.2(O)(COOR.sup.1), —R.sup.2(O)(NR.sup.1.sub.2), —R.sup.2(O)(SR.sup.1); B is selected from —OR.sup.1, —R.sup.2OR.sup.1, —NR.sup.1.sub.2, —R.sup.2NR.sup.1.sub.2, —SR.sup.1, R.sup.2SR.sup.1, —COOR.sup.1, —R.sup.2CO.sub.2R.sup.1, —CONR.sup.1.sub.2, —R.sup.2CONR.sup.1.sub.2; C is selected from —OR.sup.1, —R.sup.2OR.sup.1, —NR.sub.2, —R.sup.2NR.sup.1.sub.2, —COOR.sup.1, —C(O)R.sup.1, —CONR.sup.1.sub.2, —C(NR.sup.1)(NR.sup.1.sub.2), —NO.sub.2, —OC(O)NR.sup.1.sub.2, —OC(O)OR.sup.1, —OC(O)R.sup.1, —N(R.sup.1)C(O)OR.sup.1, —N(R.sup.1)C(O)R.sup.1, —R.sup.2CO.sub.2R.sup.1, —R.sup.2C(NR.sup.1)(NR.sup.1.sub.2), —R.sup.2CONR.sup.1.sub.2, —R.sup.2NO.sub.2, —R.sup.2OC(O)NR.sup.1.sub.2, —R.sup.2OC(O)OR.sup.1, —R.sup.2OC(O)R.sup.1, —R.sup.2NR.sup.1C(O)OR.sup.1, —R.sup.2N(R.sup.1)C(O)R.sup.1, —SO.sub.3R.sup.1, —R.sup.2SO.sub.3R.sup.1, —R.sup.2OC(S)NR.sup.1.sub.2, —R.sup.2SC(O)NR.sup.1.sub.2, —SO.sub.2R.sup.1, —R.sup.2SO.sub.2R.sup.1, —R.sup.2(OR.sup.1).sub.2, —R.sup.2(OR.sup.1)(COOR.sup.1), —R.sup.2(OR.sup.1)(NR.sup.1.sub.2), —R.sup.2(OR.sup.1)(SR.sup.1), —R.sup.2(COOR.sup.1).sub.2, —R.sup.2(NR.sup.1.sub.2)(COOR.sup.1), -R.sup.2NO2, -R.sup.20C(0)NR.sup.12, -R.sup.20C(0)0R.sup.1, -R.sup.20C(0)R.sup.1, -R.sup.2NR.sup.1C(0)01:2.sup.1, -R.sup.2N(R′)C(0)R.sup.1, —R.sup.2(SR.sup.1)(COOR.sup.1), —R.sup.2(SR.sup.1).sub.2, —R.sup.2(NR.sup.1.sub.2)(SR.sup.1), —R.sup.2(NR.sup.1.sub.2).sub.2, —R.sup.2(O).sub.2, —R.sup.2(OR.sup.1)(O), —R.sup.2(O)(COOR.sup.1), —R.sup.2(O)(NR.sup.1.sub.2), —R.sup.2(O)(SR.sup.1); R.sup.1 is independently selected from hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl, aralkyl, heteroaryl, and wherein R.sup.1 is optionally substituted with one or more of alkyl, halogen, haloalkyl, amino, alkylamino, alkoxy, hydroxyl, alkylhydroxyl, thiol, alkylthiol, cyano and nitro; R.sup.2 is independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, alkyoxy, aryl, aralkyl, and heteroaryl, and wherein R.sup.2 is optionally substituted with one or more of alkyl, halogen, haloalkyl, amino, alkylamino, alkoxy, hydroxyl, alkylhydroxy, thiol, alkylthiol, cyano and nitro; A, B and C are bonded to core Q, wherein Q is selected from the group consisting of aryl, heteroaryl, heterocycloalkyl and cycloalkyl groups, and wherein Q is optionally further substituted with one or more substituents selected from hydroxy, halogen, haloalkyl, haloalkoxy, amino, nitro, cyano, aminoalkyl, dialkylamino, aminoalkenyl, alkyloxy, alkenyloxy, alkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heterocycloalkyl, cycloalkyl, carboxy, carboxyalkyl, carboxyalkenyl, thiol, alkylthio, arylthio, aralkylthio, nitro or cyano, each of which may be optionally further substituted.

    21. The system of claim 19 or 20, wherein the organic linker has the structure of Formula (II) or a salt or anion thereof: ##STR00008## wherein: A, B and C are as defined for Formula (I); and R3, R4 and R5 are independently selected from the group consisting of hydrogen, hydroxy, halogen, haloalkyl, haloalkoxy, amino, nitro, cyano, aminoalkyl, dialkylamino, aminoalkenyl, alkyloxy, alkenyloxy, alkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heterocycloalkyl, cycloalkyl, carboxy, carboxyalkyl, carboxyalkenyl, thiol, alkylthio, arylthio, aralkylthio, nitro or cyano, each of which may be optionally further substituted,

    22. The system of any one of claims 19-21, wherein the sorbent further comprises polymeric materials, membranes, resins, biomolecules, clays, ceramics, carbon, inorganic oxides, and a combination thereof.

    23. The system of any one of claims 19-22, wherein the sorbent is positioned in an adsorption column.

    24. The system of any one of claims 19-23, wherein the sorbent is positioned on a fixed bed.

    25. The system of any one of claims 19-24, further comprising a pressure swing system for varying the pressure in the chamber.

    26. The system of any one of claims 19-25, further comprising a temperature swing system for varying the temperature in the chamber.

    Description

    BRIEF DESCRIPTION OF THE FIGURES

    [0087] FIG. 1 shows a molecular model of the SBU of MUF-16, wherein the octahedra are Co(II) cations. One-dimensional cobalt(II) chains are connected by μ.sub.2-bridging carboxylate groups of the Haip ligands (H.sub.2aip=5-aminoisophthalic acid), and nitrogen donor atoms from Haip ligands of adjacent SBUs coordinate at axial positions.

    [0088] FIG. 2 shows a molecular model of a part of a layer of four connected SBUs of MUF-16.

    [0089] FIG. 3 shows a molecular model of the inter-layer hydrogen bonding in MUF-16.

    [0090] FIG. 4 shows a molecular model of the structure of MUF-16, including a view down the 1-dimensional SBUs, pores and interlayer hydrogen bonding between the layers.

    [0091] FIG. 5 shows PXRD patterns of MUF-16, MUF-16(Mn) and MUF-(Ni) with comparisons between measurements on as-synthesized bulk samples and diffractograms predicted from single crystal x-ray diffraction (SCXRD) structures.

    [0092] FIG. 6 shows volumetric adsorption (filled circles) and desorption (open circles) isotherms of CO.sub.2, C.sub.2H.sub.2, C.sub.2H.sub.6 and CH.sub.4 measured at 195 K for MUF-16.

    [0093] FIG. 7 shows volumetric adsorption (filled circles) and desorption (open circles) isotherms of different gases by MUF-16(Mn) at 293 K.

    [0094] FIG. 8 shows volumetric adsorption (filled circles) and desorption (open circles) isotherms of different gases by MUF-16(Ni) at 293 K.

    [0095] FIG. 9 shows (a) Experimental H.sub.2, Ar, N.sub.2, CH.sub.4, O.sub.2, C.sub.2H.sub.2, C.sub.2H.sub.4, C.sub.2H.sub.6, C.sub.3H.sub.6 and C.sub.3H.sub.8 adsorption (solid spheres) and desorption (open spheres) isotherms of MUF-16 measured at 293 K. (b) Predicted IAST selectivities, displayed with a log scale, of MUF-16 for various gas mixtures at 293 K.

    [0096] FIG. 10 shows kinetic profiles of different gas uptake by MUF-16 at 293 K upon exposing an evacuated sample to a dose of gas equal to its measured total adsorption of that gas at 1 bar. q is the amount of uptake at time t and qo is the final uptake amount.

    [0097] FIG. 11 shows mixed-gas isotherms and selectivity of MUF-16 predicted by IAST for a mixture of 0.1/99.9 CO.sub.2/C.sub.2H.sub.2 at 293 K.

    [0098] FIG. 12 shows mixed-gas isotherms and selectivity of MUF-16 predicted by IAST for a mixture of 15/85 CO.sub.2/CH.sub.4 at 293 K.

    [0099] FIG. 13 shows mixed-gas isotherms and selectivity of MUF-16 predicted by IAST for a mixture of 15/85 CO.sub.2/CH.sub.4 at 293 K up to 50 bar.

    [0100] FIG. 14 shows mixed-gas isotherms and selectivity of MUF-16 predicted by IAST for a mixture of 1/99 CO.sub.2/N.sub.2 at 293 K.

    [0101] FIG. 15 shows mixed-gas isotherms and selectivity of MUF-16 predicted by IAST for a mixture of 20/80 CO.sub.2/H.sub.2 at 293 K.

    [0102] FIG. 16 shows mixed-gas isotherms and selectivity of MUF-16 predicted by IAST for a mixture of 50/50 CO.sub.2/C.sub.3H.sub.6 at 293 K.

    [0103] FIG. 17 shows mixed-gas isotherms and selectivity of MUF-16 predicted by IAST for a mixture of 50/50 CO.sub.2/C.sub.3H.sub.8 at 293 K.

    [0104] FIG. 18 shows IAST selectivity for a 50/50 mixture of CO.sub.2/N.sub.2 at 293 K for the MUF-16 family.

    [0105] FIG. 19 shows IAST selectivity for a 15/85 mixture of CO.sub.2/N.sub.2 at 293 K for the MUF-16 family.

    [0106] FIG. 20 shows IAST selectivity for a 50/50 mixture of CO.sub.2/CH.sub.4 at 293 K for the MUF-16 family.

    [0107] FIG. 21 shows IAST selectivity for a 50/50 mixture of CO.sub.2/C.sub.2H.sub.2 at 293 K for the MUF-16 family.

    [0108] FIG. 22 shows IAST selectivity for a 50/50 mixture of CO.sub.2/C.sub.2H.sub.4 at 293 K for the MUF-16 family.

    [0109] FIG. 23 shows IAST selectivity for a 50/50 mixture of CO.sub.2/C.sub.2H.sub.6 at 293 K for the MUF-16 family.

    [0110] FIG. 24 shows IAST selectivity for a 50/50 mixture of CO.sub.2/H.sub.2 at 293 K for the MUF-16 family.

    [0111] FIG. 25 shows a breakthrough apparatus used to measure the gas separation performance of the MOFs under dynamic conditions.

    [0112] FIG. 26 shows experimental breakthrough curves for a mixture of 0.4/99.6 CO.sub.2/N.sub.2 at 1.1 bar and 293 K in an adsorption column packed with MUF-16.

    [0113] FIG. 27 shows experimental breakthrough curves for a mixture of 50/50 CO.sub.2/H.sub.2 at 1.1 bar and 293 K in an adsorption column packed with MUF-16.

    [0114] FIG. 28 shows experimental breakthrough curves for a mixture of 15/85 CO.sub.2/CH.sub.4 at 1.1 bar and 293 K in an adsorption column packed with MUF-16.

    [0115] FIG. 29 shows experimental breakthrough curves for a mixture of 15/80/4/1 CO.sub.2/CH.sub.4/C.sub.2H.sub.6/C.sub.3H.sub.8 at 1.1 bar and 293 K in an adsorption column packed with MUF-16.

    [0116] FIG. 30 shows experimental breakthrough curves for a mixture of 15/85 CO.sub.2/CH.sub.4 at 9 bar and 293 K in an adsorption column packed with MUF-16.

    [0117] FIG. 31 shows experimental breakthrough curves for a mixture of 15/80/4/1 CO.sub.2/CH.sub.4/C.sub.2H.sub.6/C.sub.3H.sub.8 at 9 bar and 293 K in an adsorption column packed with MUF-16.

    [0118] FIG. 32 shows experimental breakthrough curves for a mixture of 5/95 CO.sub.2/C.sub.2H.sub.2 at 1.1 bar and 293 K in an adsorption column packed with MUF-16

    [0119] FIG. 33 shows experimental breakthrough curves for a mixture of 50/50 CO.sub.2/C.sub.2H.sub.4 at 1.1 bar and 293 K in an adsorption column packed with MUF-16.

    [0120] FIG. 34 shows experimental breakthrough curves for a mixture of 50/50 CO.sub.2/C.sub.2H.sub.6 at 1.1 bar and 293 K in an adsorption column packed with MUF-16.

    [0121] FIG. 35 shows simulated breakthrough curves for a mixture of 0.1/99.9 CO.sub.2/C.sub.2H.sub.2 at 1.1 bar and 293 K in an adsorption column packed with MUF-16.

    [0122] FIG. 36 shows simulated breakthrough curves for a mixture of 15/85 CO.sub.2/CH.sub.4 at 50 bar and 293 K in an adsorption column packed with MUF-16.

    [0123] FIG. 37 shows experimental breakthrough curves of CO.sub.2/N.sub.2 (15/85) mixture at different cycles at 293 K and 1.1 bar for MUF-16.

    [0124] FIG. 38 shows CO.sub.2 adsorption isotherms (293 K) of as-synthesized MUF-16 after four consecutive adsorption-desorption cycles, after exposing it to air with 80% humidity for 6 months, and after immersion in water for 24 hours.

    [0125] FIG. 39 shows PXRD patterns of MUF-16 showing that its structure remains unchanged after activation at 130° C. under vacuum, after isotherm measurements, after breakthrough experiments, after exposure to an air with relative humidity of >80% for at least 12 months and after immersion in water for two weeks.

    [0126] FIG. 40 shows thermogravimetric analysis curves of MUF-16, MUF-16(Mn), and MUF-16(Ni).

    [0127] FIG. 41 shows experimental breakthrough curves for a mixture of CO.sub.2/N.sub.2 (15/85) at 27° C. with and without water vapour. The water vapour is present at 82% relative humidity.

    [0128] FIG. 42 shows PXRD patterns of MUF-16 showing that its structure remains unchanged after making it into pellet with a PVDF binder.

    [0129] FIG. 43 shows CO.sub.2 adsorption isotherm of MUF-16 at 293 K showing that the inherent adsorption performance of the MOF toward CO.sub.2 remains unchanged after making it into pellet with a PVDF binder. The observed drop in capacity for the pellets arises from the 5 wt % PVDF, which is non-adsorbing.

    [0130] FIG. 44 shows experimental breakthrough curves for a mixture of CO.sub.2/N.sub.2 15/85 at 293 K and 1.1 bar in an adsorption column packed with MUF-16/PVDF pellets before and after being soaked in boiling water.

    DEFINITIONS

    [0131] Unless specifically defined otherwise, all technical and scientific terms used herein shall be taken to have the same meaning as commonly understood by one of ordinary skill in the art (for example, in materials science and chemistry).

    [0132] It is intended that reference to a range of numbers disclosed herein (e.g. 1 to 10) also incorporates reference to all related numbers within that range (e.g. 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

    [0133] The term “and/or”, e.g., “X and/or Y” shall be understood to mean either “X and Y” or “X or Y” and shall be taken to provide explicit support for both meanings or for either meaning.

    [0134] Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

    [0135] Throughout this specification, unless specifically stated otherwise or the context requires otherwise, reference to a single step, composition of matter, group of steps or group of compositions of matter shall be taken to encompass one and a plurality (i.e. one or more) of those steps, compositions of matter, groups of steps or group of compositions of matter.

    [0136] “Hydrogen” is intended to encompass isotopes of hydrogen, including deuterium.

    [0137] The term “hydrocarbon” means a saturated or unsaturated organic compound comprising a linear, branched or cyclic carbon structure, which may be functionalised or non-functionalised. Examples of non-functionalised hydrocarbons include methane (CH.sub.4), C2 and C3 hydrocarbons, including ethane, propane, butane, ethene, propene, 1-butene, 2-butene, ethyne (acetylene), propyne, 1-butyne and 2-butyne. Functionalised hydrocarbons are hydrocarbons that are substituted with one or more functional groups or heteroatoms. Examples of functionalised hydrocarbons include alcohols, aldehydes, amines, alkylhalides and alkylnitriles. The term “functionalised C1-3 hydrocarbon” means any functionalised hydrocarbon having up to three carbon atoms, and includes, for example, methanol, ethanol, propanol, formaldehyde, acetone, acetic acid, methyl bromide, methyl iodide, methylamine, ethylamine, hydrogen cyanide, cyanogen, and acetonitrile.

    [0138] The term “alkyl” means any saturated non-functionalised hydrocarbon radical and is intended to include both straight-chain and branched-chain alkyl groups. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, n-pentyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, 2-ethylpropyl, n-hexyl, and 1-methyl-2-ethylpropyl. The term “C1-C6 alkyl” means any alkyl radical having up to 6 carbon atoms.

    [0139] The term “alkenyl” means any non-functionalised hydrocarbon radical having at least one double bond, and is intended to include both straight- and branched-chain alkenyl groups. Examples of alkenyl groups include, but are not limited to, ethenyl, n-propenyl, iso-propenyl, n-butenyl, iso-butenyl, sec-butenyl, t-butenyl, n-pentenyl, 1,1-dimethylpropenyl, 1,2-dimethylpropenyl, 2,2-dimethylpropenyl, 1-ethylpropenyl, 2-ethylpropenyl, n-hexenyl, and 1-methyl-2-ethyl propenyl.

    [0140] The term “alkynyl” means any non-functionalised hydrocarbon radical having at least one triple bond, and is intended to include both straight- and branched-chain alkynyl groups. Examples of alkynyl groups include, but are not limited to, ethynyl, n-propynyl, iso-propynyl, n-butynyl, iso-butynyl, sec-butynyl, t-butynyl, n-pentynyl, 1,1-dimethylpropynyl, 1,2-dimethylpropynyl, 2,2-dinnethylpropynyl, 1-ethylpropynyl, 2-ethylpropynyl, n-hexynyl, and 1-methyl-2-ethylpropynyl.

    [0141] The term “alkylene” means a diradical corresponding to an alkyl group. Examples of alkylene groups include, but are not limited to, methylene and ethylene.

    [0142] The term “cycloalkyl” means a saturated or partially saturated non-aromatic carbocyclic group, having preferably from 3 to 8 ring carbon atoms. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

    [0143] The term “heterocyclyl” means a cycloalkyl group where one or more of the ring carbon atoms is replaced with one or more heteroatoms, e.g. nitrogen, oxygen or sulfur. Examples of heterocyclyl groups include, but are not limited to, pyrrolidinyl, pyrrolinyl, pyrazolidinyl, aziridinyl, thiiranyl, 1,2-dithietanyl, morpholinyl, furanyl, pyranyl, thiophenyl, isoxazolyl, furazanyl, tetrahydrofuranyl, thietanyl, piperidinyl, azetidinyl, oxiranyl, epoxide, and thiacyclohexyl.

    [0144] The term “alkoxy” means an alkyl group singular bonded to an oxygen atom.

    [0145] Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, n-butoxy, iso-butoxy, , sec-butoxy, and t-butoxy,

    [0146] The term “aryl” means an aromatic radical. Examples include monocyclic groups as well as fused groups such as bicyclic groups and tricyclic groups. Examples include, but are not limited to, phenyl, indenyl, 1-naphthyl, 2-naphthyl, azulenyl, heptalenyl, biphenyl, indacenyl, acenaphthyl, fluorenyl, phenalenyl, phenanthrenyl, anthracenyl, cyclopentacyclooctenyl, and benzocyclooctenyl.

    [0147] The term “heteroaryl” means a heterocyclic aromatic (heteroaromatic) radical. Examples include monocyclic groups as well as fused groups such as bicyclic groups and tricyclic groups. Examples include, but are not limited to, pyridyl, pyrrolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazolyl, tetrazolyl, benzotriazolyl, pyrazolyl, imidazolyl, benzimidazolyl, indolyl, isoindolyl, indolizinyl, purinyl, indazolyl, furyl, pyranyl, benzofuryl, isobenzofuryl, thienyl, thiazolyl, isothiazolyl, benzothiazolyl, oxazolyl, and isoxazolyl.

    [0148] The term “aralkyl” means an aryl group which is attached to an alkylene moiety, where aryl and alkylene are as defined above. Examples include benzyl group.

    [0149] “IAST” means “ideal adsorbed solution theory”, which can be used to predict mixed component adsorption isotherms from single component adsorption isotherms..sup.10

    DETAILED DESCRIPTION

    [0150] The inventors have developed a MOF showing the surprising property of being a nanoporous adsorbent with selectivity for CO.sub.2 over a broad range of other gases. It combines attractive non-covalent, physisorptive contacts between guest CO.sub.2 molecules and the pore surface with rapid diffusion kinetics, robustness and recyclability. While known MOF adsorbents may show selectivity for CO.sub.2 over one or two other gases, the breadth of selectivity exhibited by the MOFs of the present invention is an unusual and unexpected property.

    [0151] 1-Dimensional Chain

    [0152] The MOF of the present invention comprises a regular extended structure made from the connection of repeating metal-linker units. The repeating units comprise metal cations connected via organic linkers. Each organic linker comprises a first moiety that coordinates to and connects adjacent metal ions to form a 1-dimensional chain, also referred to herein as a secondary building unit (SBU). The MOF comprises a plurality of secondary building units (SBUs), each SBU comprising a linear chain of repeating metal-linker units.

    [0153] In an example, the SBU formula is M(L).sub.2, wherein M is a metal cation and L is the organic linker compound that links adjacent metal ions. In this example, the first moieties of two organic linkers bridge adjacent metal ions. The first moieties may coordinate at adjacent coordination sites of each metal cation.

    [0154] The first moiety comprises two donor atoms—one for coordinating to each of the adjacent metal ions. The first moiety bridges adjacent metal ions by coordination of one donor atom to each adjacent metal cation. In one example, the first moiety comprises a carboxylate group.

    [0155] FIGS. 1 to 4 show the structure of an exemplary MOF of the present invention, MUF-16, in which the linker is 5-aminoisophthalate and the metal is cobalt (II). The octahedra represent the metal (for MUF-16, this is Co(II)). FIG. 1 shows an SBU of MUF-16, wherein the repeating unit in the SBU is -[Mμ.sup.2(OCRO).sub.2Mμ.sup.2(OCRO).sub.2]— (where R symbolises the remainder of the organic linker). The Co(II) cations are linked by p.sup.2-bridging carboxylate groups of two 5-aminoisophthalate (Haip.sup.−) linkers.

    [0156] 2-Dimensional Layer

    [0157] Each organic linker in a first SBU comprises a second moiety comprising a donor atom that coordinates to a metal cation in an adjacent SBU. Coordination of the donor atom to the adjacent SBU forms a two-dimensional layer of SBUs.

    [0158] In the MOFs exemplified herein, the functional group of the second moiety is an amino group.

    [0159] FIG. 2 shows a section of a two-dimensional layer of SBUs of MUF-16. The amino group of the linkers in a first SBU coordinates to Co(II) ions in an adjacent SBU.

    [0160] 3-Dimensional Framework

    [0161] The three-dimensional framework structure is formed by the stacking of the two-dimensional layers. Adjacent layers are connected together via linker-to-linker hydrogen bonding interactions between H-bonding moieties of the organic linker.

    [0162] The H-bonding moiety of one linker, located in a first layer, forms a hydrogen bonding interaction with an H-bonding moiety of a linker located in a second layer adjacent the first layer.

    [0163] In MUF-16, the H-bonding moieties are carboxylic acid or carboxylate groups. Where the H-bonding moieties are carboxylate groups, some or all of these are protonated. These H-bonding interactions link the two dimensional layers into three-dimensional frameworks.

    [0164] FIG. 3 shows the inter-layer hydrogen bonding in MUF-16. Carboxylic acid groups of 5-aminoisophthalate (Haip.sup.-) hydrogen bond to each other to connect the 2-dimensional layers into a 3-dimensional framework.

    [0165] With reference to crystallographic axes and the visualisation of MUF-16 in FIG. 4, the three-dimensional framework can be described as comprising 1 dimensional chains (or SBUs) of carboxyl-bridged metal ions along one of the crystallographic axes; 2-dimensional layers of adjacent SBUs across a crystallographic plane formed in part by amine coordination to the metal; and the stacking of a plurality of 2-dimensional layers via carboxylic acid bridges. Pores are formed between adjacent 2-dimensional layers. The pores are co-axial with the SBU.

    [0166] Pores

    [0167] The porosity of the MOF is defined by open pores having a cross section diameter sufficient for guest species to enter. The pores are arranged in a substantially regular pattern. The geometry of the pores is defined by metal-linker interactions and linker-linker interactions (in particular, linker-to-linker hydrogen bonding). The pores may 3-dimensional, 2-dimensional or 1-dimensional pores. For example, the pores may be linear, substantially 1-dimensional, channels or interconnected networks of pores extending in 2- or 3-dimensions. In one example, the pores are linear channels.

    [0168] Guest species may enter the pore of the MOF and be adsorbed on the MOF. In this way, the MOF is able to capture, store, sequester and/or purify gases or mixtures of gases. The adsorption of molecules within the pores depends on the relative steric and electronic interactions between the MOF and the guest species. The cross section of the pores determines, at least in part, whether molecules may enter the pores of the MOF. Favourable electronic interactions, such as bonding, contribute towards MOF affinity and selectivity for adsorption of the guest species. Examples of favourable electronic interactions include: van der Waals interactions, hydrogen bonding, dipole-dipole and ion-dipole interactions.

    [0169] Referring to FIGS. 3 and 4, the pores of the MOF are defined between the 2-dimensional layers of connected SBUs and are substantially coaxial with the SBUs. In this way, the pores are defined in part by the interlayer distance, which is itself defined in part by the linker-to-linker bonding interactions. The pores of MUF-16 are elliptical in cross-section, having their longer dimension defined by the inter-layer linker-to-linker bonding. Single crystal x-ray diffraction (SCXRD) structural characterisation of the frameworks show one-dimensional channels running along a crystallographic axis with an approximate cross-section of approximately 6.8×2.9 Å, accounting for the van der Waals surfaces of the atoms, for MUF-16 and its Mn and Ni analogues.

    [0170] The pore environment may be selective for a particular guest species. Thus, the MOF can be used to adsorb one species of molecule from a mixture. Selectivity for a particular species arises because the MOF can interact, and form stabilising bonding interactions, with a first species more strongly than a second species. Thus, the target species can be captured (e.g., separated) from the gas mixture such that the concentration of the first species in the gas mixture is substantially reduced.

    [0171] Organic Linker

    [0172] As described in Example 1, an exemplary linker of the present invention is 5-aminoisophthalic a cid (H.sub.2aip) and negatively charged anions thereof (e.g. 5-aminoisophthalate, Haip.sup.−). With respect to 5-aminoisophthalate (Haip.sup.−), the first moiety is a carboxylate group, in which the two oxygen atoms of the functional group are donor atoms bridging two metal cations. The 1-dimensional propagation of metal/first moiety bonding forms a SBU with a formula of ML.sub.2 (see FIG. 1). The second moiety is an amino group, in which the nitrogen atom of the functional group is a donor atom which coordinates to a metal cation in an adjacent SBU. The propagation of metal/second moiety bonding forms a 2-dimensional layer of connected adjacent SBUs (see FIG. 2). The hydrogen bonding moiety is a carboxylic acid functional group, in which the carboxylic acid group hydrogen bonds to a carboxylic acid functional group of a linker in an adjacent 2-dimensional layer. H-bonding between carboxylic acids in adjacent 2-dimensional layers of MUF-16 allows the propagation of the structure along an axis orthogonal to the propagation of the 2-dimensional layer, wherein the linker-to-linker interaction comprises carboxyl-carboxyl bridges.

    [0173] Each organic linker in the MOF of the present invention coordinates to three metal ions. The linker coordinates to two metal ions via the donor atoms of the first moiety, and the linker coordinates to another metal ion via the donor atom of the second moiety. Each linker bonds to another linker via linker-to-linker interactions.

    [0174] Metal Cation

    [0175] As described in Example 1, MOFs have been synthesised with metal cations selected from Co.sup.2+, Mn.sup.2+ and Ni.sup.2+. Structural characterization of the exemplary MOFs shows that the structure is preserved where the metal cations are substituted. Gas adsorbance properties and selectivity for CO.sub.2 is also preserved. Based on this finding, the identity of the metal cation is not considered essential to the framework's selectivity for CO.sub.2. Accordingly, the metal cation, M, can include Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, Be.sup.2+, Mg.sup.2+, Sr.sup.2+, Ba.sup.2+, Sc.sup.3+, Sc.sup.2+, Sc.sup.+, Y.sup.3+, Y.sup.2+, Y.sup.+, Ti.sup.4+, Ti.sup.3+, Ti.sup.2+, Zr.sup.4+, Zr.sup.3+, Zr.sup.2+, Hf.sup.4+, Hf.sup.3+, V.sup.5+, V.sup.4+, V.sup.3+, V.sup.2+, Nb.sup.5+, Nb.sup.4+, Nb.sup.3+, Nb.sup.2+, Ta.sup.5+, Ta.sup.4+, Ta.sup.3+, Ta.sup.2+, Cr.sup.6+, Cr.sup.5+, Cr.sup.4+, Cr.sup.3+, Cr.sup.2+, Cr.sup.+, Cr, Mo.sup.6+, Mo.sup.5+, Mo.sup.4+, Mo.sup.3+, Mo.sup.2+, Mo.sup.+, Mo, W.sup.6+, W.sup.5+, W.sup.4+, W.sup.3+, W.sup.2+, W.sup.+, Mn.sup.7+, Mn.sup.6+, Mn.sup.5+, mn.sup.4+, Mn.sup.3+, Mn.sup.2+, Mn.sup.+, Re.sup.+, Re.sup.6+, Re.sup.5+, Re.sup.+, Re.sup.3+, Re.sup.2+, Re.sup.+, Re, Fe.sup.6+, Fe.sup.4+, Fe.sup.3+, Fe.sup.2+, Fe.sup.+, Fe, Ru.sup.8+, Ru.sup.7+, Ru.sup.6+, Ru.sup.4+, Ru.sup.3+, Ru.sup.2+, Os.sup.8+, Os.sup.7+, Os.sup.6+, Os.sup.5+, Os.sup.4+, Os.sup.3+, Os.sup.2+, Os.sup.+, Os, Co.sup.5+, Co.sup.4+, Co.sup.3+, Co.sup.2+, Co.sup.+, Rh.sup.6+, Rh.sup.5+, Rh.sup.4+, Rh.sup.3+, Rh.sup.2+, Rh.sup.+, Ir.sup.6+, Ir.sup.5+, Ir.sup.4+, Ir.sup.3+, Ir.sup.2+, Ir.sup.+, Ir, Ni.sup.3+, Ni.sup.2+, Ni.sup.+, Ni, Pd.sup.6+, Pd.sup.4+, Pd.sup.2+, Pd.sup.+, Pd, Pt.sup.6+, Pt.sup.5+, Pt.sup.4+, Pt.sup.3+, Pt.sup.2+, Pt.sup.+, Cu.sup.4+, Cu.sup.3+, Cu.sup.2+, Cu.sup.+, Ag.sup.3+, Ag.sup.2+, Ag.sup.+, Au.sup.5+, Au.sup.4+, Au.sup.3+, Au.sup.2+, Au.sup.+, Zn.sup.2+, Zn.sup.+, Zn, Cd.sup.2+, Cd.sup.+, Hg.sup.4+, Hg.sup.2+, Hg.sup.+, B.sup.3+, B.sup.2+, B.sup.+, Al.sup.3+, Al.sup.2+, Ga.sup.3+, Ga.sup.2+, Ga.sup.+, In.sup.3+, In.sup.2+, In.sup.1+, Tl.sup.3+, Tl.sup.+, Si.sup.4+, Si.sup.3+, Si.sup.2+, Si.sup.+, Ge.sup.4+, Ge.sup.3+, Ge.sup.2+, Ge.sup.+, Ge, Sn.sup.4+, Sn.sup.2+, Pb.sup.4+, Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.2+, As.sup.+, Sb.sup.5+, Sb.sup.3+, Bi.sup.5+, Bi.sup.3+, Te.sup.6+, Te.sup.5+, Te.sup.4+, Te.sup.2+, La.sup.3+, La.sup.2+, Ce.sup.4+, Ce.sup.3+, Ce.sup.2+, Pr.sup.4+, Pr.sup.3+, Pr.sup.2+, Nd.sup.3+,Nd.sup.2+, Sm.sup.3+, Sm.sup.2+, Eu.sup.3+, Eu.sup.2+, Gd.sup.3+, Gd.sup.2+, Gd.sup.+, Tb.sup.4+, Tb.sup.3+, Tb.sup.2+, Tb.sup.+, Db.sup.3+, Db.sup.2+, Ho.sup.3+, Er.sup.3+, Tm4+, Tm.sup.3+, Yb.sup.3+, Yb.sup.2+, Lu.sup.3+, and any combination thereof.

    [0176] In a more specific example, the metal cation is selected from the group consisting of Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Sc.sup.3+, Sc.sup.2+, Y.sup.3+, Y.sup.2+, Ti.sup.3+, Ti.sup.2+, V.sup.3+, V.sup.2+, Nb.sup.3+, Nb.sup.2+, Cr.sup.3+, Cr.sup.2+, Mo.sup.3+, Mo.sup.2+, Mn.sup.3+, Mn.sup.2+, Fe.sup.3+, Fe.sup.2+, Ru.sup.3+, Ru.sup.2+, Co.sup.3+, Co.sup.2+, Rh.sup.3+, Rh.sup.2+, Ni.sup.2+, Pd.sup.2+, Zn.sup.2+, Cd.sup.2+, B.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, Tl.sup.3+, Si.sup.2+, Ge.sup.2+, Sn.sup.2+, As.sup.3+, As.sup.2+, and any combination thereof.

    [0177] Method of Preparation

    [0178] The MOF of the present invention may be prepared by combining the organic linker with the metal ion in a solvent. Preferably, the MOF is prepared under conditions which allow the self-assembly of the framework.

    [0179] Example 1 describes the preparation of exemplary MOF frameworks of the present invention, in which the linker is 5-aminoisophthalate (H.sub.2aip) and the metal ion is selected from cobalt(II), manganese(II) and nickel(II). The linker and metal ion are dissolved in a solvent and heated in a sealed vessel under autogenous pressure. The resulting MOF with the formula [M(Haip).sub.2] (M=Co, Mn or Ni) precipitates from solution in high yields.

    [0180] In their as-synthesized form the pores of the MOF may contain occluded solvent (often water). Occluded solvents can be removed from the pores of the MOF by heating, or in vacuo, or by purging with a flow of dry air, or a combination of two or more of the aforementioned methods.

    [0181] Crystallinity and Macrostructure

    [0182] Referring to Example 2, SCXRD and powder XRD show that the MOF compounds are crystalline (See Tables 1 and 2).

    [0183] As shown in FIGS. 1-4, the metal ions adopt an octahedral geometry with four carboxylate and two amino donors, arranged trans to one another, from six different linkers. More specifically, M(II) atoms with octahedral geometry line up into a 1D chain along a crystallographic b axis through bridging carboxylate groups from Haip linkers. Two adjacent chains are linked together into 2D layers by Haip linkers. One of the two carboxylate groups of each Haip linker coordinates to M(II) and the other one acts as a hydrogen-bond acceptor and donor.

    [0184] Powder XRD of Co(II), Mn(II) and Ni(II) frameworks (shown in FIG. 5) confirms the crystalline structure of the MOF of the present invention, and further confirms that the framework is preserved with the substitution of metal ions.

    [0185] Adsorption and Selectivity

    [0186] The MOF frameworks are accessible to a range of incoming gases, including monoatomic and diatomic gases, carbon dioxide, and C1-C3 hydrocarbons. Referring to Example 3 and Table 3, nitrogen adsorption isotherms measured at 77 K gave BET surface areas of 215, 209 and 238 m.sup.2/g for MUF-16, MUF-16(Mn), and MUF-16(Ni), respectively. Total pore volumes of 0.11 cm.sup.3/g were measured for all three frameworks. These values are comparable with the geometric surface areas and pore volumes calculated from the crystallographic coordinates.

    [0187] The MOF of the present invention has particular use in the adsorption of carbon dioxide. The capacities of the MOFs of the present invention to host CO.sub.2 is considerable: both MUF-16 and MUF-16(Ni) take up 2.13 mmol/g (48 cm.sup.3/g) at 1 bar, and MUF-16(Mn) adsorbs 2.25 mmol/g (50.5 cm.sup.3/g). This equates to approximately 0.9 molecules of CO.sub.2 per metal site. CO.sub.2 adsorption isotherms for MUF-16, MUF-16(Mn) and MUF-16(Ni) (FIGS. 6 to 8) rise steeply at low pressures and nearly plateau towards 1 bar, which indicates a strong affinity of the frameworks for the CO.sub.2 guests.

    [0188] The pores of the MOF of the present invention are nearly saturated at 293 K and 1 bar, so CO.sub.2 uptake is only marginally higher at 273 K, showing that the MOF of the present invention can be readily used at, and above, ambient temperatures.

    [0189] Electronic interactions are physisorptive or non-covalent in nature. XRD analysis of the position and orientation of the CO.sub.2 in the pores of MUF-16(Mn) (see Example 2) suggests that one of the electronegative oxygen atoms of the CO.sub.2 molecule engages in N—H . . . O and C—H . . . O interactions with hydrogen atoms of amino and phenyl groups, respectively. Similarly, the electropositive carbon atom of the CO.sub.2 molecule contacts an oxygen atom of a non-coordinated carboxylate group. Therefore, the data suggests that the selectivity for CO.sub.2 is, at least in part, due to the complementary electronic interactions between the pore walls and the δ+ and δ' regions of carbon dioxide.

    [0190] The MOFs of the present invention are shown herein to preferentially adsorb carbon dioxide from a mixture of gases. Referring to Examples 3 to 5, the high uptake of CO.sub.2 by the MOFs of the present invention stands in contrast to other gases. Referring to FIG. 9(a), experimental adsorption isotherms of H.sub.2, Ar, N.sub.2, CH.sub.4, O.sub.2,C.sub.2H.sub.2, C.sub.2H.sub.4, C.sub.2H.sub.6, C.sub.3H.sub.6 and C.sub.3H.sub.8 showed that only modest quantities of these gases are adsorbed. For example, and as shown in Table 6, MUF-16 takes up just 1.32 and 1.20 cm.sup.3/g of N.sub.2 and CH.sub.4 at 1 bar and 293 K, respectively, which rises to the highest value amongst the measured adsorbates of 5.35 cm.sup.3/g for C.sub.3H.sub.6.

    [0191] The MOFs of the present invention have a selective uptake of CO.sub.2 over N.sub.2, having uptake ratios between 17.6 and 36.2 (see Table 5). The preferential uptake of CO.sub.2 over N2 for MUF-16 is comparable to the benchmark physisorbent [Cd.sub.2L(H.sub.2O)],.sup.11 and elevated beyond materials such as SIFSIX-2-Cu-i.sup.12 and DICRO-3-Ni-i.sup.13. While some materials that trap CO.sub.2 by chemisorption show higher uptake ratios, including for example the amine-functionalised framework en-Mg-dobpdc,.sup.14 such chemisorptive frameworks require significant energy input to desorb the captured CO.sub.2 and are therefore not suited for many CO.sub.2 separation applications.

    [0192] MUF-16 adsorbs more CO.sub.2 than C2 and C3 hydrocarbons, having uptake ratios of between 9.0 and 15.9 at 293 K and 1 bar (see Table 6). This contrasts with typical physisorbents, which show a preference for unsaturated hydrocarbons especially when bonding between the guest's pi-electrons and open metal sites can occur..sup.15

    [0193] While the low uptake of the monatomic and diatomic gases is a well-established function of their small polarizabilities and small (or zero) quadrupole moments, the diminished affinity for the larger (C1-3) non-functionalised hydrocarbon guests is notable. Without wishing to be bound by theory, the inventors believe that the diminished affinity for the C2-C3 hydrocarbon guests is due to the guests' electropositive regions around the termini of the hydrocarbons, which leads to repulsive interactions with the framework pore surface. For example, the positive electrostatic potential at the termini of ethyne, ethene, ethane and propane is in contrast with the negative electrostatic potential of the termini of CO.sub.2. The uptake of ethyne (and other non-functionalised hydrocarbons) in MUF-16 may be explained by relatively energetically unfavourable repulsive forces arising due to interactions between δ+ areas of ethyne and δ+ areas of MUF-16, and similarly repulsive interactions between 5-areas of ethyne and δ− areas of MUF-16, assuming the ethyne molecules were to occupy the sites crystallographically observed for the binding of CO.sub.2.

    [0194] Without wishing to be bound by theory, the inventors believe that the affinity and selectivity for CO.sub.2 in the MOF of the present invention is due to, firstly, the dimensions of the framework pores match the size of the CO.sub.2 molecules, which allows these molecules to be enveloped by multiple non-covalent contacts. Secondly, CO.sub.2 carries electronegative potential at its terminal oxygen atoms, compared to the electropositive central carbon atom. CO.sub.2 therefore has more favourable interactions with the pore surface.

    [0195] While the selectivity of the MOF of the present invention for CO.sub.2 in the presence of certain hydrocarbons, monatomic and diatomic gases has been exemplified herein, the inventors believe it is a reasonable extrapolation for the MOF of the present invention to have similar adsorptive properties for guest molecules with similar properties. Examples include carbon disulfide, nitrous oxide, and C1-C3 functionalised hydrocarbons (including hydrogen cyanide, acetonitrile, C1-C3 alcohols, C1-C3 aldehydes, C1-C3 nitriles, C1-C3 alkyl halides and cyanogen). It is a reasonable extrapolation for the MOF to be similarly selective for these compounds in the presence of non-functionalised hydrocarbons, monatomic and diatomic gases.

    [0196] The low affinity of the MOF of the present invention towards non-functionalised hydrocarbons and monatomic and diatomic gases exemplified herein means that, in addition to carbon dioxide, the MOF is also selective for small polar and polarisable compounds from a mixture further comprising non-functionalised hydrocarbons, monoatomic and diatomic gases. Accordingly, the inventors consider that the MOF will selectively adsorb carbon dioxide, carbon disulfide, nitrous oxide, water, hydrogen sulfide, hydrogen cyanide, cyanogen and C1-C3 functionalised hydrocarbons from a mixture that includes non-functionalised hydrocarbons.

    [0197] In order to rule out the possibility that the selectivity mechanism of the MOFs of the present invention rely on molecular sieving (i.e. size exclusion), the inventors measured gas adsorption isotherms at 195 K which revealed that MUF-16 is able to take up significant amounts of C.sub.2H.sub.6. FIG. 6 shows the volumetric adsorption and desorption isotherms of CO.sub.2, C.sub.2H.sub.2, C.sub.2H.sub.6 and CH.sub.4 for MUF-16, and clearly shows that each molecule can freely enter the pore network. FIGS. 7 to 9, which show volumetric adsorption/desorption isotherms of MOFs of the present invention at ambient temperatures, show that the uptake of ethyne, ethene, ethane, methane and nitrogen is low at ambient temperatures. FIG. 9(a) further shows low uptake of oxygen, argon, hydrogen, propane and propene. The kinetics of adsorption of guest molecules CO.sub.2, N.sub.2, CH.sub.4, C.sub.2H.sub.4, C.sub.2H.sub.6, C.sub.2H.sub.2 onto MUF-16 were measured by exposing an evacuated sample of the MOF to a dose of gas equal to its measured total adsorption of that gas at 1 bar. The results are shown in FIG. 10 (q is the amount of uptake at time t and q0 is the final uptake amount), which shows that all gases measured reach their equilibrium uptake in well under one minute and the uptake rates are similar for all gases. Therefore, thermodynamic rather than kinetic effects have the most decisive impact on the differential affinity of these gases for MUF-16.

    [0198] Iast—Gas Mixtures

    [0199] While the uptake ratios for the MOFs of the present invention provide an excellent indication of preferential affinity, the selectivity for a particular component of a gas mixture can be quantified by Ideal Adsorbed Solution Theory (IAST) calculations. IAST calculations for the MOFs of the present invention show exceptional preference for CO.sub.2 in the presence of Nz, H.sub.2, certain C1-C3 hydrocarbons and mixtures thereof.

    [0200] Referring to Example 4 and Table 6, the MOFs of the present invention have high selectivity for CO.sub.2 in the presence of N.sub.2, H.sub.2, CH.sub.4, C.sub.2H.sub.2, C.sub.2H.sub.4, C.sub.2H.sub.6, C.sub.3H.sub.6, and C.sub.3H.sub.8 (also see FIG. 9(b)). As the IAST data described herein show that CO.sub.2 can be separated from mixtures of hydrogen, nitrogen and certain C1-C3 hydrocarbons, and in light of the uptake data for 02 and Ar (see FIG. 9(a)), it is reasonable to expect that the MOFs of the present invention are highly selective for CO.sub.2 in the presence of other gases.

    [0201] FIGS. 11 to 24 show mixed gas isotherms and selectivity of MUF-16 predicted by IAST for combinations of gases. IAST calculations show the MOFs of the present invention remain highly selective for CO.sub.2 in the presence of H.sub.2, N.sub.2, and non-functionalised C1-3 hydrocarbons at pressures above 1 bar. For example, FIG. 13 shows both uptake data and IAST calculations demonstrating that the MOFs of the present invention remain highly selective for CO.sub.2 in the presence of methane at 50 bar (5,000 kPa).

    [0202] Breakthrough Testing

    [0203] The IAST data discussed herein are backed up by experimental data from breakthrough measurements showing performance of the MOFs under real operating conditions. An apparatus comprising a chamber for receiving the MOF of the present invention was assembled. The apparatus allowed the MOF to be exposed to a mixture of gases at particular pressures and temperatures. Pressure and temperature of the MOF could be varied by temperature and pressure controllers. Specific details of the breakthrough apparatus are described in Example 5 and shown in FIG. 25.

    [0204] Breakthrough separation measurements showed that MUF-16 selectively adsorbs CO.sub.2 from mixtures comprising H.sub.2, N.sub.2, and mixtures of non-functionalised C1-3 hydrocarbons. Breakthrough curves for separation of CO.sub.2 from gas mixtures are shown in FIGS. 26 to 37. Breakthrough data is shown in Table 9. The data show that MUF-16 efficiently retained CO.sub.2 and delivered pure N.sub.2 for CO.sub.2/N.sub.2 mixtures in proportions of 50/50, 15/85, 1/99 and 0.4/99.6. Similarly, CO.sub.2 is retained and pure hydrocarbon is delivered from hydrocarbon/CO.sub.2 mixtures, as shown by breakthrough data for the mixtures of 15/85 CO.sub.2/CH.sub.4, 5/95 CO.sub.2/C.sub.2H.sub.2, 50/50 CO.sub.2/C.sub.2H.sub.4 and 50/50 CO.sub.2/C.sub.2H.sub.6.

    [0205] The simulated breakthrough profile shown in FIG. 35 extends the experimental results by demonstrating that MUF-16 is capable of eliminating trace quantities of CO.sub.2 from C.sub.2H.sub.2 (i.e. 0.1% CO.sub.2 in an ethyne stream) to produce a stream of high-purity C.sub.2H.sub.2.

    [0206] The simulated breakthrough profile shown in FIG. 36 models the separation of CO.sub.2 from CO.sub.2/CH.sub.4 mixtures at high pressures (9 bar), and shows that CO.sub.2 is cleanly removed from the gas stream. The dynamic uptake capacity for CO.sub.2 is higher at 9 bar than that measured at 1 bar. Extrapolation of these data to pressures relevant to natural gas processing (˜40-60 bar) predicts that MUF-16 can efficiently sequester CO.sub.2 from raw natural gas streams.

    [0207] The breakthrough testing indicates that MUF-16 is an excellent adsorbent under dynamic conditions. The dynamic capacities for CO.sub.2 derived from these breakthrough measurements of MOF-16 are nearly identical to the equilibrium capacities at the corresponding partial pressures (see Table 9). This indicates that the MOFs of the present invention are an excellent adsorbent under dynamic conditions, which stems from a combination of (i) differential affinity for the two gases, (ii) the short time delay for the appearance of the non-adsorbed N.sub.2 and its near-vertical elution profile.

    [0208] Regeneration

    [0209] The MOFs of the present invention can be fully regenerated and recycled for CO.sub.2 capture. During breakthrough testing, complete CO.sub.2 desorption of MUF-16 was achieved by placing it under a dynamic vacuum or by purging with a flow of dry air (CO.sub.2 content <200 ppm) at room temperature and 1 bar. The CO.sub.2 profile in the eluent from the adsorption bed was measured to show the CO.sub.2 is released within 25 minutes.

    [0210] Alternatively, the adsorption bed could be regenerated under a dynamic vacuum (turbomolecular pump) for around 15-20 minutes at room temperature.

    [0211] Alternatively, the adsorption bed could be regenerated at elevated temperatures.

    [0212] FIG. 37 shows the recyclability of MUF-16; the MOF shows virtually no change in its separation activity after 200 breakthrough-regeneration cycles for the separation of CO.sub.2/N.sub.2. In line with its high stability, MUF-16 maintains its separation performance and uptake capacity over this period.

    [0213] Stability/Robustness

    [0214] The MOFs of the present invention also have extraordinary water resistance and thermal stability. FIG. 38 shows that the uptake of CO.sub.2 for MUF-16 remains substantially constant after four cycles, being exposed to air for six months, and after being immersed in water for 24 hours. Shown in FIG. 39, PXRD of MUF-16 samples shows that the MOF structure remains unchanged after activation at 130° C. under vacuum, after isotherm measurements, after breakthrough experiments, after exposure to an air with relative humidity of >80% for at least 12 months and after immersion in water for two weeks. MUF-16(Mn) and MUF-16(Ni) have similar stability in the presence of water, humidity and temperatures of 130° C. under vacuum.

    [0215] Thermogravimetric analysis demonstrated the thermal stability of MUF-16, and its Mn and Ni analogues beyond 330° C. under nitrogen (FIG. 40).

    [0216] The ability of the MOF to capture CO.sub.2 from gas mixtures is unaffected by the presence of water vapour in the gas mixture. FIG. 41 shows a breakthrough curve for a mixture of CO.sub.2 and N.sub.2 (15/85) at 27° C. in the presence of water vapour (82% relative humidity) compared to the same gas mixture without water vapour, and demonstrates that MUF-16 efficiently retains CO.sub.2 and delivers pure N.sub.2 in the presence of water.

    [0217] Pelletisation/Incorporation Into Other Materials

    [0218] Incorporation of the MOF of the present invention into other materials improves the handling of the MOF and widens the potential uses for their gas capture properties. These components may include materials such as, but not limited to, polymers, biomolecules, resins, ceramics, carbon (e.g. activated carbon) and inorganic oxides. The composite material may take the form, for example, of a pellet, membrane, sheet, or monolith. For example, the MOF may be combined with further components to form a membrane, such as gas separation membranes.

    [0219] As an additional measure to render the MOF more compatible with typical large-scale gas separation processes, Example 8 describes the incorporation of a MOF of the present invention into a composite. MUF-16 was combined with a quantity of polyvinylidene fluoride (PVDF) to make composite pellets. The PXRD profile of the pellets comprising MUF-16 was substantially the same as the profile for MUF-16, indicating that the crystalline structure of the material is preserved on the molecular scale (see FIG. 42). The pellets exhibit the same adsorption profile as MUF-16, showing that the gas adsorption characteristics are unchanged. For example, FIG. 43 shows that MUF-16/PVDF exhibits the same CO.sub.2 adsorption isotherms compared to MUF-16 (the observed drop in capacity for the PVDF pellets arises from the 5 wt % PVDF, which is non-adsorbing). The pellets maintain the stability and robustness observed for MUF-16, as shown by FIG. 44 which illustrates that the pellets retain their CO.sub.2/N.sub.2 separation performance even after the pellets are soaked in boiling water.

    EXAMPLES

    [0220] All starting compounds and solvents were used as received from commercial sources without further purification unless otherwise noted.

    Example 1: Preparation of MUF-16, MUF-16(Mn), and MUF-16(Ni)

    [0221] ##STR00003##

    [0222] Synthesis of MUF-16:

    [0223] A mixture of Co(OAc).sub.2.4H.sub.2O (0.625 g, 2.5 mmol), 5-aminoisophthalic acid (1.8 g, 10 mmol), methanol (80 mL) and water (5 ml) were sonicated for 20 min in a sealed 1000 mL Schott bottle, which was then heated in a pre-heated oven at 70° C. for 2 hours under autogenous pressure.

    [0224] After cooling the oven to room temperature, the resulting pink crystals were isolated by decanting off the mother liquor, then washed with methanol several times and dried under vacuum at 130° C. for 20 h. Yield: 0.98 g (94% based on cobalt) of guest-free MUF-16.

    [0225] Alternative Synthesis of MUF-16:

    [0226] A mixture of Co(OAc).sub.2.4H.sub.2O (5.0 g, 20 mmol), 5-aminoisophthalic acid (12 g, 68 mmol), methanol (490 mL) and water (40 ml) were sonicated for 20 min in a sealed 2000 mL Schott bottle, which was partly (˜20%) prefilled with glass beads. The bottle was then heated in a pre-heated oven at 70° C. for 5 hours under autogenous pressure. After cooling the oven to room temperature, the resulting pink crystals were isolated by decanting off the mother liquor, washed with methanol several times and dried under vacuum at 130° C. for 20 h. Yield: 7.8 g (92% based on cobalt) of guest-free MUF-16.

    [0227] Synthesis of MUF-16(Mn) and MUF-16(Ni):

    ##STR00004##

    [0228] A mixture of M(ClO.sub.4).sub.2.6H.sub.2O (where M=Mn or Ni) (1.25 mmol), 5-aminoisophthalic acid (2.50 mmol, 0.45 g), and NH.sub.4NO.sub.3 (2.50 mmol, 0.20 g) with a mixed-solvent of CH.sub.3CN (20 mL) and CH.sub.3OH (15 mL) were sonicated for 20 min and sealed in a 100 mL Teflon-lined stainless-steel reaction vessel and heated at 160° C. for two days under autogenous pressure. After cooling the oven to room temperature, the resulting brownish crystals were isolated by decanting off the mother liquor, washed with methanol several times and dried under vacuum at 130° C. for 20 h. Yields: 0.21 g (40% based on Mn) of guest free MUF-16(Mn), and 0.28 g (53% based on Ni) of guest-free MUF-16(Ni).

    Example 2: Structural Characterisation

    [0229] Single crystal X-ray diffraction characterisation of MUF-16, Mn and Ni analogues was performed using a Rigaku Spider diffractometer equipped with a MicroMax MM007 rotating anode generator (Cu. radiation, 1.54180 Å), high-flux Osmic multilayer mirror optics, and a curved image plate detector was used to collect SCXRD and PXRD data.

    [0230] MOF crystals were analysed after washing with methanol. Room temperature data collections produced better refinement statistics than low temperature data collections. All atoms were found in the electron density difference map.

    [0231] All atoms were refined anisotropically, except hydrogen atoms and certain atoms of the water molecules in the pores. A solvent mask was calculated for MUF-16(Ni) and 124 electrons were found in a volume of 308 Å.sup.3 in 1 void per unit cell. This is consistent with the presence of three disordered water molecules per asymmetric unit, which account for 120 electrons per unit cell.

    [0232] The SCXRD data were integrated, scaled and averaged with FS Process Rigaku (Rigaku Corporation: Tokyo, J., 1996). SHELX,.sup.16 under OLEX.sup.17, was used for structure solution and refinement.

    [0233] For PXRD measurements, unless otherwise noted, samples were kept damp with solvent prior to and during measurements. The two-dimensional images of the Debye rings were integrated with 2DP to give 2θ vs I diffractograms. The data were obtained from freshly prepared MOF samples that had been washed several times with methanol. Predicted powder patterns were generated from single crystal structures using Mercury™.

    TABLE-US-00001 TABLE 1 Crystal data and structure refinement details for MUF-16, MUF-16(Mn), and MUF-16(Ni). MUF16(Mn), MUF-16(Ni). MUF-16(M = Co) (M = Mn) (M = Ni) Formula Co(Haip).sub.2 .Math. 2H.sub.2O Mn(Haip).sub.2 .Math. 3H.sub.2O Ni(Haip).sub.2 .Math. 3H.sub.2O Empirical formula C.sub.16H.sub.16CoN.sub.2O.sub.10 C.sub.16H.sub.18MnN.sub.2O.sub.11 C.sub.16H.sub.18N.sub.2NiO.sub.11 Formula weight 455.24 471.28 473.3 Temperature/K 292 292 293 Crystal system monoclinic monoclinic monoclinic Space group I2/a I2/α I2/a a/Å 15.3514(15) 25.2367(14) 15.4963(11) b/Å 4.4232(4) 4.57990(10) 4.5780(2) c/Å 25.614(4) 15.4895(11) 25.230(2) α/° 90 90 90 β/° 94.294(10) 96.046(8) 96.177(8) γ/° 90 90 90 Volume/Å.sup.3 1734.4(4) 1780.34(17) 1779.5(2) Z 4 4 4 ρ.sub.calc/g cm.sup.−3 1.743 1.758 1.564 μ/mm.sup.−1 8.357 6.682 2.02 F(000) 932 972 856 Resolution range for data/Å 0.81 0.81 1 Reflections collected 7472 14132 6610 Independent reflections 1594[R.sub.int = 0.0918, 1668 [R.sub.int = 0.1054, 925 [R.sub.int = 0.0917, R.sub.sigma = 0.0917] R.sub.sigma = 0.1158] R.sub.sigma = 0.0852] Data/restraints/parameters 1594/2/136 1668/1/149 925/0/126 Goodness-of-fit on F2 1.301 1.152 1.649 Final R indices[I > 2σ(I)] R.sub.1 = 0.1185, R.sub.1 = 0.0740, R.sub.1 = 0.1517, wR.sub.2 = 0.3035 wR.sub.2 = 0.1821 wR.sub.2 = 0.3672 Final R indices[all data] R.sub.1 = 0.1576, R.sub.1 = 0.1350, R.sub.1 = 0.2061, wR.sub.2 = 0.3785 wR.sub.2 = 0.2421 wR.sub.2 = 0.4467 Largest diff. peak/hole/eÅ.sup.−3 0.93/−1.26 0.57/−0.51 0.77/−0.83

    [0234] The MOF of the present invention was characterized with SCXRD in a glass capillary both under vacuum and loaded with CO.sub.2 (about 1.1 bar). SCXRD data for MUF-16(Mn) under vacuum and loaded with CO.sub.2 is shown in Table 2.

    TABLE-US-00002 TABLE 2 SCXRD data and refinement details of guest-free and CO.sub.2-loaded MUF-16(Mn) MUF-16(Mn) CO.sub.2-loaded in vacuo MUF-16(Mn) Formula Mn(Haip).sub.2 Mn(Haip).sub.2 .Math. CO.sub.2 Empirical formula C.sub.16H.sub.12MnN.sub.2O.sub.8 C.sub.17H.sub.12MnN.sub.2O.sub.10 Formula weight 415.22 459.23 Temperature/K 292 292 Crystal system monoclinic monoclinic Space group I2/a I2/a a/Å 15.4872(11) 15.5719(10) b/Å 4.51930(10) 4.52010(10) c/Å 25.4913(13) 25.438(2) α/° 90 90 β/° 97.080(16) 97.108(8) γ/° 90 90 Volume/Å.sup.3 1770.56(17) 1776.7(2) Z 4 4 ρ.sub.calc/g cm.sup.−3 1.558 1.717 μ/mm.sup.−1 6.512 6.646 F (000) 844.0 932.0 Data range for refinement/Å 0.90 1.08 Reflections collected/ind. 7515/1214 8177/713 [R.sub.int = 0.1632, [R.sub.int = 0.1104, R.sub.□ = 0.1964] R.sub.□ = 0.0804] Data/restraints/parameters 1214/0/129 713/90/136 Goodness-of-fit on F.sup.2 0.862 1.216 Final R indexes[I >= 2σ (I)] R.sub.1 = 0.0510, R.sub.1 = 0.0868, wR.sub.2 = 0.0954 wR.sub.2 = 0.2280 Final R indexes[all data] R.sub.1 = 0.1341, R.sub.1 = 0.1278, wR.sub.2 = 0.1112 wR.sub.2 = 0.2915 Largest diff. peak/hole/eÅ.sup.−3 0.35/−0.48 0.56/−0.58

    Example 3: Uptake—Adsorption/Desorption Isotherms

    [0235] Unless otherwise stated, CO.sub.2 adsorption isotherms were collected at 293 K. The isotherms rise steeply at low pressures and nearly plateau towards 1 bar, which indicates a strong affinity of the frameworks for the CO.sub.2 guests.

    [0236] The as-synthesized samples were washed with anhydrous methanol several times and 50-1000 mg was transferred into a pre-dried and weighed sample tube. Large sample quantities were used to measure isotherms of the weakly-adsorbing gases to ensure reliable results. To activate the sample, it was heated at rate of 10° C./min to a temperature of 130° C. under a dynamic vacuum with a turbomolecular pump for 20 hours.

    [0237] A CO.sub.2 adsorption isotherm at 77 K established the permanent porosity of MUF-16 and gave a BET surface area of 215 m.sup.2/g and a pore volume of 0.11 cm.sup.3/g (Table 3)..sup.18 Similar results for MUF-16(Mn) and MUF-16(Ni) are shown in Table 3. These values are consistent with the geometric surface area of about 310 m.sup.2/g and pore volume of 0.1 cm.sup.3/g calculated from the crystallographic coordinates.

    [0238] The isosteric heat of adsorption (Q.sub.st) of CO.sub.2 was calculated by the implementation of virial method..sup.19 The isosteric heat of adsorption (Q.sub.st) at zero-coverage was calculated to be around 33-37 kJ/mol (see Table 5), increasing at higher loadings which is consistent with gradual expansion of network structure (energy consumed) during adsorption.

    TABLE-US-00003 TABLE 3 Calculated and experimentally determined properties of the MUF-16 family. MUF-16 MUF-16(Mn) MUF-16(Ni) Geometric surface area 313 315 313 (m.sup.2/g, Zeo + +) BET surface area (m.sup.2/g, from 215 209 238 experimental N.sub.2 isotherm/77 K) Calculated void fraction 17.3 17.0 16.7 (%, RASPA2) Calculated pore volume 0.10 0.11 0.11 (cm.sup.3/g, RASPA2) Pore volume 0.11 0.12 0.11 (cm.sup.3/g, from experimental N.sub.2 isotherm/77 K) Largest cavity diameter (Å) 3.63 3.58 3.61 Pore limiting diameter (Å) 2.95 2.95 2.96

    TABLE-US-00004 TABLE 4 Uptake capacity of CO.sub.2 at 293 K and 1 bar of MUF-16. Uptake (wt %) MUF-16 9.38 MUF-16(Ni) 9.41 MUF-16(Mn) 9.90

    TABLE-US-00005 TABLE 5 Metrics relevant to CO.sub.2/N.sub.2/CH.sub.4 separations for MUF-16 (293K, 1 bar) CO.sub.2 | N.sub.2 | CH.sub.4 IAST selectivity uptakes Q.sub.st(CO.sub.2) Uptake ratio CO.sub.2/N.sub.2 CO.sub.2/CH.sub.4 CO.sub.2/H.sub.2 Material (cc/g) (kJ/mol) CO.sub.2/N.sub.2 CO.sub.2/CH.sub.4 (15/85) (50/50) (20/80) MUF-16 47.8 | 33 36.2 39.8 631 6686 9695 1.3 | 1.2 MUF-16(Mn) 50.5 | 38 17.6 16.3 256  470  301 2.9 | 3.1 MUF-16(Ni) 48.0 | 37 20.8 17.3 281 1215 6828 2.3 | 2.8

    Example 4: IAST Selectivity

    [0239] Mixed gas adsorption isotherms and gas selectivities for different mixtures of CO.sub.2/C.sub.2H.sub.2, CO.sub.2/C.sub.2H.sub.4, CO.sub.2/C.sub.2H.sub.6, CO.sub.2/N.sub.2, CO.sub.2/CH.sub.4 and CO.sub.2/H.sub.2 at 293 K were calculated based on the ideal adsorbed solution theory (IAST) proposed by Myers and Prausnitz..sup.20 The pyIAST package was used to perform the IAST calculations..sup.21 In order to predict the sorption performance of MUF-16 toward the separation of binary mixed gases, the single-component adsorption isotherms were first fit to a Dual Site Langmuir or Dual Site Langmuir Freundlich model as below:

    [00001] q = q 1 b 1 P 1 + b 1 P + q 2 b 2 P 1 + b 2 P q = q 1 b 1 P 1 / t 1 1 + b 1 P 1 / t 1 + q 2 b 2 P 1 / t 2 1 + b 2 P 1 / t 2

    [0240] Where q is the uptake of a gas; P is the equilibrium pressure and q.sub.1, b.sub.1, t.sub.1, q.sub.2, b.sub.2 and t.sub.2 are constants. These parameters were used subsequently to carry out the IAST calculations.

    [0241] A summary of the gas adsorption data and IAST-calculated selectivities for the MUF-16 family is provided in Table 6.

    TABLE-US-00006 TABLE 6 Summary of gas adsorption data and IAST-calculated selectivities for the MUF-16 family at 1 bar and 293 K. MUF-16 MUF-16(Mn) MUF-16(Ni) Gas(es) (M = Co) (M = Mn) (M = Ni) Uptake.sup.a CO.sub.2 47.78 50.5 47.97 N.sub.2 1.32 2.86 2.30 CH.sub.4 1.20 3.10 2.77 H.sub.2 0.64 1.10 0.78 C.sub.2H.sub.2 3.99 9.69 7.53 C.sub.2H.sub.4 3.17 8.31 5.42 C.sub.2H.sub.6 3.06 8.81 5.67 C.sub.3H.sub.6 5.35 — — C.sub.3H.sub.8 4.82 — — Selectivity CO.sub.2/N.sub.2.sup.b 630 260 280 CO.sub.2/CH.sub.4.sup.c 6690 470 1220 CO.sub.2/H.sub.2.sup.d 9690 300 6830 CO.sub.2/C.sub.2H.sub.2.sup.c 510 31 46 CO.sub.2/C.sub.2H.sub.4.sup.c 600 600 130 CO.sub.2/C.sub.2H.sub.6.sup.c 600 55 110 CO.sub.2/C.sub.3H.sub.6.sup.c 260 — — CO.sub.2/C.sub.3H.sub.8.sup.c 84 — — .sup.aIn cm.sup.3/g. .sup.b15/85 ratio at 1 bar and 293 K as calculated by IAST. .sup.c50/50 ratio at 1 bar and 293 K as calculated by IAST. .sup.d20/80 ratio at 1 bar and 293 K as calculated by IAST.

    Example 5: Breakthrough Testing

    [0242] The feasibility of CO.sub.2 separations under dynamic condition using the MOF of the present invention was investigated using an adsorption bed in a breakthrough apparatus in accordance with the apparatus shown in FIG. 25.

    [0243] In a typical breakthrough experiment, activated MUF-16 (0.9 g) was placed in an adsorption column (6.4 mm in diameter×11 cm in length) to form a fixed bed. The adsorbent was activated at 130° C. under high vacuum for 7 hours and then the column was left under vacuum for another 3 hours while being cooled to 20° C. The column was then purged under a 20 mLN/min flow of He gas for 1 hr at 1.1 bar prior to the breakthrough experiment.

    [0244] Gas mixtures of CO.sub.2/N.sub.2, CO.sub.2/CH.sub.4, CO.sub.2/H.sub.2 and CO.sub.2/CH.sub.4 C.sub.2H.sub.6+C.sub.3H.sub.8 in varying proportions were introduced to the column at 1.1 bar (and 9 bar for CO.sub.2/CH.sub.4 and CO.sub.2/CH.sub.4+C.sub.2H.sub.6+C.sub.3H.sub.8) and 20° C.

    [0245] A feed flowrate of 6 mLN/min was set (10 mLN/min for 0.4/99.6 CO.sub.2/N.sub.2 mixture, and 6.85 mLN/min for 5/95 mixture of CO.sub.2/C.sub.2H.sub.2). The operating pressure was controlled at 1.1 or 9 bar with a back-pressure regulator. The flowrate of He in the feed was kept constant at 2 mLN/min for all the experiments unless otherwise stated. The outlet composition was continuously monitored by a SRS UGA200 mass spectrometer. The CO.sub.2 was deemed to have broken through from the column when its concentration reached 600 ppmv.

    [0246] The adsorbates (primarily CO.sub.2) were stripped from the column to regenerate the adsorbent by purging with dry air at ambient temperature (20° C.) and a flow rate of 20 mLN/min at 1.1 bar. The effluent from the adsorption bed was monitored by mass spectrometry to show that all of the CO.sub.2 was removed at 20° C. over a period of around 25 minutes, with no further loss of CO.sub.2 observed at 40, 60, 80 or 130° C.

    [0247] Experimental breakthrough separation test results are summarised in Table 9.

    [0248] Simulated breakthrough experiments were performed to investigate separations at low CO.sub.2 concentrations, such as trace concentrations. First, the mass transfer coefficient used for the simulated breakthrough curves was empirically tuned based on experimental breakthrough curves. This produced a match between simulated and experimental breakthrough curves. Using this mass transfer coefficient, breakthrough curves were predicted for feed compositions of 0.1/99.9 CO.sub.2/C.sub.2 hydrocarbons at 1.1 bar and 293 K. FIG. 35 shows the simulated breakthrough curve of 0.1/99.9 CO.sub.2/C.sub.2H.sub.2. Simulated breakthrough curves for C.sub.2H.sub.4 and C.sub.2H.sub.6 are substantially identical. These calculations revealed MUF-16 is capable of eliminating trace quantities of CO.sub.2 from C2 hydrocarbons.

    [0249] The simulation of breakthrough curves was carried out using a previously reported method..sup.22 A value for the mass transfer coefficient (k) was obtained by empirical tuning the steepness of the predicted breakthrough curves to match the experimental curve. The mass transfer coefficient tuned in this way was later used to predict breakthrough curves for other feed mixtures and operating pressures. A summary of adsorption column parameters and feed characterizations are presented in Table 7. The simulation of breakthrough curves for CO.sub.2/C.sub.2 hydrocarbons was carried out using the method reported above. A summary of adsorption column parameters and feed characterizations are presented in Table 8.

    TABLE-US-00007 TABLE 7 Adsorption column parameters and feed characterizations used for the simulations for MUF-16. Adsorption bed Feed Length: 110 mm Flow rate: 6 mL.sub.N/min Diameter: 6.4 mm Temperature: 293 K Amount of adsorbent in the bed: 0.9 g Pressure: 1.1 bar Adsorbent density: 1.674 g/cm.sup.3 Carrier gas flow rate: Adsorbent average radius: 0.2 mm No carrier gas was used k.sub.CO2: 0.029 s.sup.−1 k.sub.CH4: 0.00021 s.sup.−1

    TABLE-US-00008 TABLE 8 Adsorption column parameters and feed characterizations used for the simulations for MUF-16. Adsorption bed Feed Length: 110 mm Flow rates: Diameter: 6.4 mm 6 mL.sub.N/min for equimolar and 0.1/99.9 mixtures, and 6.85 Amount of adsorbent mL.sub.N/min for the 5/95 mixture. in the bed: 0.9 g Bed voidage: 0.84 Temperature: 293 K Adsorbent average radius: Pressure: 1.1 bar 0.2 mm k.sub.CO2: 0.021 s.sup.−1 Carrier gas (He) flow rate: 2 mL.sub.N/min. k.sub.C2H2: 0.024 s.sup.−1

    Example 6: Regeneration of the Adsorbent

    [0250] The adsorption bed used in Example 5 was subsequently regenerated by purging with with a flow of air, and the breakthrough experiment was repeated. As shown in FIG. 37, breakthrough curves were substantially unchanged after 200 exposure/purge cycles of exposure to a CO.sub.2/N.sub.2 15/85 gas mixture (6 mL/min).

    TABLE-US-00009 TABLE 9 Summary of inlet gas feed streams, outlet compositions and associated data for experimental breakthrough tests using a MUF- 16 adsorbent bed. Upper limit CO.sub.2 concentration Inlet CO.sub.2 for CO.sub.2 in effluent at Dynamic Equilibrium Total partial concentration Breakthrough breakthrough adsorption adsorption pressure pressure Flowrate in effluent point in CO.sub.2 point capacity capacity Gas Mixture (bar) (bar) (mL.sub.N/min) (ppmv) (min) (ppmv) (mmol/g) (mmol/g) CO.sub.2/N.sub.2 (50/50) 1 0.5 6 500 10.6 600 1.57 1.85 CO.sub.2/N.sub.2 (15/85) 1 0.15 6 520 24.1 600 1.08 1.23 CO.sub.2/N.sub.2 (1/99) 1 0.01 6 530 40.7 600 0.12 0.17 CO.sub.2/N.sub.2 (0.4/99.6) 1 0.004 10 500 28.5 600 0.06 0.09 CO.sub.2/CH.sub.4 (50/50) 1 0.5 6 500 10.6 600 1.53 1.85 CO.sub.2/CH.sub.4 (15/85) 1 0.15 6 520 25.6 600 1.13 1.23 CO.sub.2/CH.sub.4 (15/85) 9 0.15 6 360 44.8 600 2.01 — CO.sub.2/CH.sub.4 +C.sub.2H.sub.6 + C.sub.3H.sub.8 1 0.15 6 520 24.6 600 1.09 1.23 (15/80/4/1) CO.sub.2/CH.sub.4 +C.sub.2H.sub.6 + C.sub.3H.sub.2 9 0.15 6 390 42.5 600 1.93 — (15/80/4/1) CO.sub.2/C.sub.2H.sub.2 (50/50)* 1 0.33 6 500 12.3 600 1.23 1.64 CO.sub.2/C.sub.2H.sub.2 (5/95) 1 0.035 6.85 540 15.1 600 0.18 0.46 CO.sub.2/C.sub.2H.sub.4 (50/50)* 1 0.33 6 500 11.9 600 1.19 1.64 CO.sub.2/C.sub.2H.sub.6 (50/50)* 1 0.33 6 500 12.2 600 1.22 1.64 CO.sub.2/H.sub.2 (50/50) 1 0.5 6 500 10.8 600 1.62 1.85 CO.sub.2/H.sub.2 (15/85) 1 0.5 6 510 24.4 600 1.11 1.85

    Example 7: Stability

    [0251] Aging experiments of the MOFs of the present invention were performed as follows: as-synthesized samples were analysed with PXRD after washing several times with methanol, after activation at 130° C. under vacuum, after isotherm and breakthrough measurements (See Examples 3 and 5), after exposure to air at >80% relative humidity for 10 months, and after immersion in water for two weeks. Results are shown in FIG. 39.

    [0252] Thermogravimetric analysis measurements were performed as follows: Freshly prepared MOF samples were washed with methanol, and then activated at 130° C. under vacuum for 10 hours. Samples were exposed to air for 1 hour and then transferred to an aluminium sample pan, and then TGA measurements were commenced under an N.sub.2 flow with a heating rate of 5° C./min. Results of thermogravimetric analysis for MUF-16, MUF-16(Mn) and MUF-16(Ni) are shown in FIG. 40.

    [0253] PXRD and isotherm measurements were performed according to the parameters described herein.

    Example 8: Pelletisation

    [0254] MUF-16 was incorporated into pellets using polyvinylidene difluoride (PVDF) as a binder according to the following method: [0255] 1. MUF-16 (-0.5 g) was gently ground using mortar and pestle. [0256] 2. The ground sample was transferred to a 20 ml vial and 0.5 ml of DMF was added. A viscous suspension was obtained after sonicating for half an hour. The suspension was stirred for another 30 mins. [0257] 3. PVDF powder ( 50 mg) was gradually added over the course of 1 hour to make a viscus paste. [0258] 4. The paste was transferred into a plastic syringe using a spatula and pressed it out in one thin noodle onto a glass slide.

    [0259] 5. The noodle was cut into small pellets and dried under vacuum at 120° C. for 4 hours.

    [0260] The inventions described and claimed herein have many attributes and embodiments including, but not limited to, those set forth or described or referenced in the Summary of the Invention. It is not intended to be all-inclusive and the inventions described and claimed herein are not limited to or by the features or examples identified in the Summary of the Invention, which is included for purposes of illustration only and not restriction.

    [0261] Although the invention has been described by way of example, it should be appreciated that variations and modifications may be made without departing from the scope of the invention as defined in the claims. Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred in this specification. The specific compositions and methods described herein are representative of preferred examples and are exemplary and not intended as limitations on the scope of the invention. Other aspects and examples will occur to those skilled in the art upon consideration of this specification, and are encompassed within the spirit of the invention as defined by the scope of the claims. It will be readily apparent to one skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, or limitation or limitations, which is not specifically disclosed as essential. Thus, for example, in each instance described or used herein, in embodiments or examples of the present invention, any of the terms “comprising”, “consisting essentially of”, and “consisting of” may be replaced with either of the other two terms in the specification. Also, the terms “comprising”, “including”, “containing”, etc. are to be read expansively and without limitation. The assays and methods illustratively described herein suitably may be practiced in differing orders of steps, and that they are not necessarily restricted to the orders of steps indicated herein or in the claims. Further, as used or described herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Under no circumstances may the patent be interpreted to be limited to the specific examples or embodiments or methods specifically disclosed herein.

    [0262] The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intent in the use of such terms and expressions to exclude any equivalent of the features shown and described or portions thereof, but it is recognised that various modifications are possible within the scope of the invention as claimed. Thus, it will be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts disclosed herein may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as described herein, and as defined by the appended claims.

    [0263] The invention has been described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the invention. This includes the generic description of the invention with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein. Other embodiments are within the following claims.

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