Crystal Engineering: Metal Organic Frameworks PDF

Chapter 16 Crystal Engineering: Metal Organic Frameworks Objectives: Coordination polymers and crystal engineering MOFs with polydentate polypyridyl derivatives MOFs with carboxylate linkers MOF with polynuclear building nodes Interpenetrating MOF’s Porous coordination polymers 1 Coordi...

Chapter 16 Crystal Engineering: Metal Organic Frameworks Objectives: Coordination polymers and crystal engineering MOFs with polydentate polypyridyl derivatives MOFs with carboxylate linkers MOF with polynuclear building nodes Interpenetrating MOF’s Porous coordination polymers 1 Coordination Polymers Coordination polymers (CPs) are rapidly emerging inorganic–organic solid state materials. First Coordination Polymer (Robson: 1990) They are constructed from assembling of metal ion or metal cluster with organic ligands through coordination bonds to form one-, two-, and three-dimensional structures. They have widespread application such as gas storage/separation, catalysis, ion exchange, drug delivery, and optoelectronics. 2 Crystal Engineering Making crystals by design, with specific and predicted properties Crystal engineering: Organic or Inorganic Hoskins and Robson (1987): demonstrated that network with predictable architectures can be engineered by related strategy based on the interaction of metals with ligand. 3 Strategies in Coordination Chemistry 4 Building Block approach or node-and-spacer approach Generate CP using simple extension of transition metal or metal cluster coordination chemistry (Zaworotko et al.) Multifunctional ligands Metal act as a node and ligand acts as linker 5 6 Examples of ligands (Connectors) 7 Schematic representation of some of the simple 1D, 2D, and 3D coordination polymers formed from the metal “nodes”(red) and organic “spacers” (blue): (a) cubic, (b) cubic diamondoid, (c) hexagonal diamondoid, (d) square grid, (e) molecular ladder, (f) zigzag chain, and (g) helix. A. M. P. Peedikakkal,* N. N. Adarsh “Porous Coordination Polymers”, Functional Polymers. Polymers and Polymeric Composites: A Reference Series. Springer, Cham, (2018), P. 181-223. 8 Analysis of Frameworks: Topology A.F. Wells notation Honeycomb : (6,3) topology 6 is the number of nodes in the shortest circuit and 3 is the connectivity of each node Uniform net: (n,p) notation: n is the size of smallest circuit and p is the connectivity of nodes Non uniform net: Schlafli symbol 9 {p,q} dodecahedron is a regular polyhedron with Schläfli symbol {5,3}, having 3 pentagons around each vertex. 10 Wells notation (n,p) for uniform nets n is the size of smallest circuit and p is the connectivity of nodes 3 Common architectures based on hexagons, squares and triangles 11 Examples of non regular 2D networks 12 3D MOFs Topologies: Most common: diamond and primitive cubic (alpha-Po) structures Dimond cubic structure primitive cubic (alpha-Po) Structure Other topologies: PtS, CdSO4, CaB6, NbO, rutile, etc. 13 MOF with Polypyridyl ligands 14 1D MOF with Polypyridyl ligands 15 2D MOF with Polypyridyl ligands 16 2D sheet with 4,4’-bpy Figure. [Zn(4,4’-bipyridine)2(H2O)2·SiF6]n 17 Metal-Organic Rotaxane Frameworks 18 3D MOFs examples Td nodes: [Cu(bpy)2]PF6 – Diamondoid topology Oh nodes: – [Ag(pyrazine)2](SbPF6) – [Sc(bpy-NN-dioxide)3]X3 (X=NO3-, CF3SO3-, ClO4-) – α-polonium topology Layer-pillared 3D – [M(pyz)2(NO2)]ClO4 (M=Co, Cu) : (4,4) sheet of M-pyz connected by bridging nitrito Tritopic ligands: 1,3,5-tricyanobenzene (TCB): – [Ag(TCB)(CF3SO3)] Honycomb sheet 19 Diamondoid topology Td nodes: [Cu(bpy)2]PF6 Diamondoid topology 20 Diamondoid topology TCTPM= 4,4′,4′′,4′′′ tetracyanotetraphenylmethane + Cu(I) 21 TCB + Ag Ag(I) Layer-pillared 3D MOF using bpy [Zn(4,4’-biypyridyl)2(SiF6)]n viewed along the b- and c-axis, respectively Layer-pillared 3D MOF using bpy Pictoral representation of pillared square grids to form permanently porous, high surface area materials. Octahedral node and α-polonium topology 25 3D MOFs Example with an octahedral node and α-polonium topology 26 Flexible Bis-Pyridyl Derivatives More structural Diversity 27 MOFs with carboxylate ligands Oxalate – 0D to 3D – [M2(Ox)3]2-, [MIMIII(ox)3]2-, [MIIMIII(ox)3]- -can form 2D, 3D homo and bimetallic networks – 2D and 3D depends on the choice of counter ions – When counterion is NR4+, 2D layers of hexagonal honeycomb is formed (Fig. 16.12) 28 Oxalate based MOFs Dimensionality : 1-3 29 MOFs based on benzene 1,4-dicarboxylate – 1D to 3D – Porous networks 30 Example: MOF-5 Yaghi et al. 2003 31 MOFs based on Benzene tricarboxylic acids BTC, Benzene tricarboxylic acid, trimesic acid, eg: HKUST-1 – Porous multidimensional networks – Flexible tripodal benzene-1,3,5-triacetic acid 32 Btc coordination modes 33 MOFs with Polynuclear Building Nodes Introduction of metal clusters into MOFs leads to new functional solid-state materials Carboxylic acid ligands provides wide range of rigid network due to their ability to aggregate metal ions into clusters termed as secondary building units (SBU) Common SBUs: – – – – square paddle wheel [M2(COO)4] Octahedral basic zinc acetate cluster Trigonal prismatic oxo-centered trimers Trigonal planar 34 Common SBUs paddle wheel 35 Dinuclear building nodes (Square paddle wheel) 36 Cu(NO3)2.3H2O + [Cu3(BTC)2(H2O)3]n Synthesis of Cu-BTC 37 Peedikakkal et al., ACS Omega 2020, 5, 28493−28499 PtS Reticular chemistry Yaghi and co-workers introduced SBU units with large rigid vertices joined by rigid organic links to produce extended frameworks of high structural stability. In this way, large class of MOFs materials has been synthesized. This chemistry is termed “Reticular Chemistry” which concerns the linking of molecular building blocks into predetermined structures using strong bonds. 39 40 MOF-2 in 1998 (2D-MOF) Dinuclear Cu2+ paddle wheel SBUs are connected by ditopic BDC linkers to form layers of square topology 41 MOF-5 MOF-5 is composed of octahedral Zn4O(—COO)6 SBUs, consisting of four tetrahedral ZnO4 units sharing a common vertex, joined by ditopic BDC linkers to give a 3D framework structure of primitive cubic (pcu) topology open porous structure large cavities make up 61% of the unit cell volume and are filled with solvent molecules 42 MOF-5 3D MOF based on octahedral Zn4O(—COO)6 SBUs and ditopic linear linkers 43 44 MOF-5 XRD pattern 45 46 Isoreticular MOFs pore size can be expanded with the long linkers biphenyl, tetrahydropyrene, pyrene, and terphenyl Eddaoudi et.al SCIENCE, 2002 Vol 295, Issue 5554, pp. 469-472 47 HKUST-1 48 MOF with Two different Connectors 49 M3O and M4O Nodes (SBU) M3O = V, Zn, Fe, Cr, and Cu Trigonal Prism joint MOF: (MIL-88) Several 3D MOFs of [Fe3O(O2C-)6] Materials of Institute Lavoisier (MILs) M4O = [Zn4O(O2C-)6 Octahedral joint MOF-5 : alpha-Po, stable up to 400 °C and highly porous 50 M3O Nodes Example : [Fe3O(COO)6] 51 High nuclearity Building Nodes High nuclearity clusters can form MOF SBUs Example: [Ni6(OH)6(1,4-cdc)3(H2O)6] 2D structure, hexanuclear prismatic nickel cluster SBU 52 Topology of interpenetration Interpenetrating: two or more networks penetrated without connecting each other. Two polymeric nets that are not connected and cannot be separated without breaking bonds Long ligands favor interpenetration parallel and inclined interpenetrating sheets 53 2D interpenetration 54 Interpenetration in 3D Most common interpenetrating 3D are: Diamondoid and alpha-polonium nets 55 Interpenetration in 3D Two-fold Interpenetration in MOF-5 56 Interpenetration in 3D Most common interpenetrating 3D are: Diamondoid and alpha-polonium nets Chem. Commun., 2012,48, 10328-10330 57 Porous CPs Application: catalysis, gas storage, gas separation, molecular recognition, drug delivery, sensors. Kitagawa divide pore walls into three types: – No special substituents in the ligands – Introduction of hydrogen bonding sites – Incorporation of metal sites capable of forming coordinative unsaturated metal centers (metalloligands) Interpenetration vs. Porosity: a problem 58 Avoiding Interpenetration Presence of Counterions Guest Aromatic molecules: naphthalene, pyrene Design framework in which interpenetration is forbidden-best strategy. 59 Types of Porous structures 1St Generation : micropore, sustained with only guest molecules and show irreversible collapse on the removal of guest molecules 2nd: Stable frameworks, reversibly lose and reabsorb guest molecules without change in phase or morphology 3rd : Dynamic frameworks which change their own frameworks in response to external stimuli 4th : Can tolerate post processing/modification 60 61 Types of Porous structures (Based on spatial dimension) Dots (0D cavities) Discrete cavities. Guest molecules are unable to pass out of the cavity – Eg: [Zn(CN)(NO3)(tpt)2/3] Channels (1D space): [Cu(glutarate)(bpy)], pillar layered alpha-Po. Layers (2D space) – Eg:[Co(btc)3py2]-2D Intersecting Channels (3D Space) – Eg: MOF-5 and others 62 MOFs with 1D pores N,N′-bis(isophthalic acid)-oxalamide (H4 BDPO) ACS Appl.Mater. Interfaces 2018, 10, 10965–10973. 63 Function of Porous MOFs Gas sorption or storage – First report was in 1997 (Kitagawa): [M2(bpy)3(NO3)4].xH2O (M=Co, Ni, Zn): CH4, N2, O2 gases – IRMOF-n: for H2, CH4 and CO2 – MIL-96 : CH4 and CO2 – MIL-100 and MIL-101: H2 – MIL-101: CO2 – Criteria for improvement Interaction with the gas Interpenetration: used to strengthen interaction with the gas Doping (e.g. Li+) Unsaturated metal sites Functionalization of ligands 64 MIL-100 65 Zeolitic imidazolate framework (ZIF) Sod truncated octahedron zinc(II) nitrate and imidazolate-2carboxyaldehyde (ICA) aperture of 3.5 Å and a pore size of 11.2 Å. Sod vs Rho truncated octahedra or β-cages connected in a cubic manner over six membered ring Three-dimensional array of truncated cubo-octahedra or α-cages connected by double 8-membered ring Few MOFs with their surface area 68 CO2 Storage 69 Function of Porous Structures Exchange Anion exchange properties Example: MOF cationic framework with anions in the pores first 1990 (Cu-MOF): BF4- exchanged by PF6- Separation of Neural molecules Ex. separation of Linear and branched alkene 70 Gas separation 71 MOFs in Catalysis Catalysis – Fujita in 1994: [Cd(bpy)(NO3)2] – HKUST-1 – MIL-101 – MIL-100 –… 72 MIL-101 (Cr) Cyanosilylation of aldehydes Oxidation of hydrocarbons Oxidation of sulfides Cycloaddition of CO2 and epoxides 73 MIL-100 (Fe) Friedel–Crafts benzylation Oxidation of hydrocarbons Ring-opening of epoxides Claisen Schmidt condensation Oxidation of thiophenol to diphenyl disulfide Isomerization of alpha-pinene oxide 74 Activation of CO2 75 Oxidation 76 Epoxidation 77 Wenbin Lin: Nature Chemistry 2, 838–846 (2010) Topology? Asymmetric Hydrogenation aromatic aldehydes into chiral secondary alcohols 80 C-C Coupling 81