Comparison of the PXRD patterns of AgBTB-dpt, AgBTB-dpee, AgBTB-dpey and Ag-BTB. Comparison of the PXRD patterns of AgBTB-bpy, AgBTB-dpt, AgBTB-dpee, Ag-BTB-dpey and Ag-BTB.
Introduction
Metal-organic framework
Metal-organic frameworks with metal ion/cluster and organic ligand
- Preference for coordination environment of metal cluster
- MOF synthesis with mixed carboxylate ligands
- Post-synthetic modification
- Molecular detection inside MOF structure
- Reference
The aldol intermediate is shown in orange, the methyl groups of hmtt in red, and the phenyl ring of the pcdc linker in purple. Post-synthetic modification11 is also one of the ways to synthesize different MOFs, which has the advantage of using already known structures (Figure 1.6).
Secondary Building Unit as a 6-c Node
Introduction
However, the net topology of the MOF was of low symmetry and was complicated because the MOF had both a linear trinuclear cluster as a 6-connected SBU and a. In this study, using BTB as a C3 symmetric 3-linked organic node and one of the most frequently observed cobalt carboxylate clusters, linear trinuclear Co3(COO)6, as a 6-linked SUB, we report the synthesis of two new Co/BTB MOF structures with the same 3,6-connected networks but different net topologies, depending on the local point symmetries of the 6-connected SBUs.
Experimental section
- General procedures and synthesis of MOFs
- Crystallographic data collection and refinement of the structures
The least-squares refinement of the structural model was performed under geometry constraints and displacement parameter constraints, such as EXYZ, EADP, and ISOR for the disordered DMA molecules. The least-squares refinement of the structural model was performed under a geometry constraint of DFIX, DANG, and FLAT for the disordered DMA molecule.
Results and Discussion 1 Preparations of the MOFs
- Structural descriptions and characterization of 1 and 2
Results and Discussion 2.3.1 Preparations of MFs. a) Linear trinuclear cobalt cluster as an SBU. A ball-and-stick diagram of the linear trinuclear cobalt group as a 6-bond trigonal prismatic knot with a schematic six-ligand center bond.
Conclusions
Structural Variation of Cobalt(II) Coordination Polymers: Three Polymorphs of Co3(TMA)2 [TMA = Trimesate, C6H3(COO)33-]. Two coordination polymers involving triangular and linear trinuclear Co(II) clusters created via in situ ligand synthesis.
Metal-organic Framework with Two Different Types of Rigid Triscarboxylates: Net Topology and Gas Sorption
Introduction
The diversity of metal-organic frameworks (MOFs) is due to the infinite number of combinations of the building componentsthe metal ions and organic ligands. It is well known that the Cu(II) ion with a carboxylate has a strong preference for a square shoe wheel group Cu2(COO)4L2 as a 4-, 5- or 6-linked secondary building unit (SBU) depending on the type of L-ligand.2 Reaction of the Cu(II) ion and 1,3,5-benzenetricarboxylic acid (H3BTC) of D3h symmetry, a rigid tricarboxylate ligand with three carboxylate residues in the ligand plane, leads to the MOF of a binodal 3,4-linked tbo net topology, Cu-HKUST-1.3 A similar reaction of the Cu(II) ion and 1,3,5-benzenetribenzoic acid (H3BTB) of D3. In other words, the net topologies of the MOFs depend on the symmetry of the carboxylate ligands.5–7.
The Zn(II) ion has a strong preference for a Zn4O(COO)6 cluster as an SBU in network structures.8 However, reactions of the Zn(II) ion with different carboxylic ligands can also generate other diverse carboxylate clusters, Zn3(COO) 6.9 Zn2(COO)4.10 Zn2(COO)3.11 and Zn2(COO)5.12 as SBUs, depending on the type of carboxylate ligands and reaction conditions. SBU as a 6-linked junction and the triscarboxylates as 3-linked junctions.15a–e For example, the reaction of the Zn(II) ion with the rigid H2BDC and H3BTB ligands at an optimal molar ratio resulted in 3,6- connected UMCM-1 ([Zn4O(BDC)(BTB)4/3]) of a muonet topology with Zn4O(COO)6 SBU as a 6-connected node.15a The reaction of the Zn(II) ion with mixed tris and tetrakis carboxylates yielded a MOF of unprecedented 3,4,6-c-net topology with Zn4O(COO)6 SBU as a 6-linked node, and the tris and tetrakis carboxylates as 3-linked and 4-linked, respectively nodes. 16 However, there are no reports on Zn MOFs with two different types of rigid triscarboxylates.
Experimental section
- General procedures and synthesis of the MOF
- Crystallographic data collection and refinement of the structure
- Gas sorption measurements
One BTC3 on one general position, another BTC3 on one crystallographic threefold axis, one BTB3 on the other crystallographic threefold axis, and two zinc atoms on general positions are observed as an asymmetric unit. All non-hydrogen atoms are refined anisotropically; the hydrogen atoms attached to the ligands were assigned isotropic displacement coefficients U(H) = 1.2U (C) and their coordinates were allowed to ride on their respective atoms. Structure refinement after modification of the structure factors for the electron densities corresponding to the solvent molecules and a completely disordered dimethylammonium countercation in the solvent pore (170,143 Å3, 68.8% of the unit cell volume; 124 electrons correspond to the electrons in one-third dimethylammonium ion) and 2.4 DMA molecules (or a specific combination of DMA and water molecules) per asymmetric device) with the SQUEEZE routine in PLATON21 led to better refinement and data convergence.
A portion of the N2 adsorption isotherm in the P/Po range was fitted to the BET equation to estimate the BET specific surface area.
Results and discussion
- Structural descriptions and characterization of 1
Ball-and-stick diagrams of cage A with nodes (medium-sized red balls) and edges (black stick) in (a) side and (b) top views, where the center of cage A is represented by a sphere of large purple dummy. Diagrams of A-cage plates with nodes (red balls), edges (black stick), and plates (purple) in (c) side and (d) top views. Diagrams of B-cage slabs with nodes (red balls), edges (black stick), and slabs (brown) in (c) side and (d) top views.
Ball-and-stick diagrams of C-cage with nodes (medium-sized red balls) and edges (black stick) in (a) side and (b) top views, where the center of C-cage is represented by a large sphere green dummy Diagrams showing the connection between the pores of A-cages. a) Ball-and-stick diagram of two A-cages connected via a ten-way channel and (b) corresponding plate diagram.
Conclusions
Notes
Porous Metal-organic Frameworks Based on Silver- carboxylate and its Stability Enhancement via
Postsynthetic Ligand Insertion
Introduction
Metal–organic frameworks (MOFs) are porous materials composed of coordination bonds between metal/metal ions and organic ligands.1 The structural diversity of MOFs is one of the fascinating advantages for many applications based on the intrinsic properties of various metal and functionalized ligands. 2 In a special view of metal ions in the periodic table, the properties of metal ions in the same group are somewhat similar, such as coordination number, oxidation state, etc. MIL-53 series with Al3+, Ga3+, and In3+ can be synthesized to produce isostructural MOF3 because of the similar coordination environment. In the case of copper (Cu(Ⅰ)) and silver (Ag(Ⅰ)) ions, both ions accept C≡N and carbon monoxide instead of carboxylate, as shown in many MOF structures due to the soft acid and base following the hard and soft acid principle and base (HSAB).5 In contrast to the above examples, the coordination environment of the copper ion shows a strong preference for tetrahedral geometry as three- or four-coordination number, while silver ions show a variety (two-, three-, four-, five- and more ) coordinate geometry6 despite the same electronic configuration d10.
These observations may be the result of different internal polarizabilities and SD hybridization. For these reasons, many 1D or 2D silver coordination polymers have a well-packed structure with linear (= two) coordination of silver ions and ligand. Consequently, only few MOFs with a silver cluster as the main node have been reported with experimental porosity.8 Therefore, the synthesis of MOF with silver ions and carboxylate is one of the challenges for expanding the diversity of MOF and utilizing silver properties in the future.
Experimental section
- Materials and general procedures
- Crystallographic data collection and refinement of the structures
The amount of dpee linker in 3 was estimated using both the relative proton ratio between dpee linker and BTB ligand in the 1H NMR spectrum of the sample digested in DMSO-d6 with a drop of aqueous D2SO4 solution and EA. The amount of dpt linker in 4 was estimated using both the relative proton ratio between dpt linker and BTB ligand in the 1H NMR spectrum of the sample digested in DMSO-d6 with 0.2 mL DCI aqueous solution and EA. The amount of bpy was estimated using both the relative proton ratio of bpy linker and BTB ligand in the 1H NMR spectrum of the sample digested in DMSO-d6 with a drop of aqueous DCI solution and elemental analysis.
The least-squares refinement of the structural model was performed under displacement parameter constraints such as DFIX, DANG, FLAT, ISOR, and SIMU. The amount of dipyridyl linker was estimated using both the relative proton ratio of dipyridyl linker and BTB ligand in the 1H NMR spectrum of the sample digested in DMSO-d6 with aqueous either DCl or D2SO4 solution and EA after gas sorption experiments.
Results and Discussion
- Synthesis and structure of Ag(BTB), 1
The first type of inter-silver distance occurs between the finite dinuclear clusters across the solvent channel. While the nearest inter-silver distance between the dinuclear clusters of the infinite 1D rod clusters is ~14.7 Å, the next closest inter-silver distance between the dinuclear clusters is ~15.8 Å, and so on. The second type of inter-silver distance is between the tetranuclear clusters on the opposite side of the solvent channel.
The last type of inter-silver distance is between the dinuclear cluster and the tetranuclear cluster across the solvent channel. While the nearest inter-silver distance between the dinuclear cluster and the tetranuclear cluster is ~10.9 Å and the next closest inter-silver distance is ~11.6 Å.
Since 1 lost its crystallinity during activation at a temperature higher than 50 ˚C, activated 1a was prepared by soaking the crystals of 1 in fresh EtOH and MC consecutively for 3 d and then vacuum-
- Gas sorption behaviors of the MOFs containing additional dipyridyl linkers .1 Preparation of the MOFs containing additional dipyridyl linkers for gas sorption study
- Gas sorption behaviors of the MOFs containing additional dipyridyl linkers
- Conclusions
- References
- Introduction
- Experimental section 1. General procedures
- Preparation of MOFs
- Crystallographic data collection and refinement of the structure
- Results and Discussion
- Single crystal structure analyses of the MOF and its CO 2 -bound MOF derivatives
- The vibrational mode analysis of the CO 2 molecule encapsulated in a cage
- Conclusions
- References
- Summary and conclusion
Anisotropic contractions of the solvent channels after the insertion of dpey and dpee linkers, respectively, into the framework of AgBTB. Ball-and-stick diagrams of the single-crystal structures of (b) MeOH-bound 1a at 173 K, (c) [Cu3Cl2]. Interestingly, the Lewis acidic carbon atom (C1C) of the bound CO2 molecule no longer interacts with the Lewis basic nitrogen atom (N3) of the ligand.
Temperature-dependent single-crystal structure analyzes revealed that the interaction between the bound CO2 molecule and the framework of the MOF is temperature-dependent. The temperature-dependent separation of the two bending peaks also supports the temperature-dependent interaction between the CO2 molecule and the framework of the MOF. While reaction of the Zn(NO3)2∙6H2O with 1,3,5-benzenetribenzoic acid and H3BTC generated an intricate 3-D network of an unprecedented 3,3,3,5-c net topology through a structurally rare Zn2(COO) )5.
Analyzes of the temperature-dependent SCXRD structure revealed that the interaction between the bound CO2 molecule and the MOF framework is temperature-dependent.
Acknowledgements
