Tuning the Topology and Functionality of Metal−Organic Frameworks by Ligand Design
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- 2 December 2010
- journal article
- research article
- Published by American Chemical Society (ACS) in Accounts of Chemical Research
- Vol. 44 (2), 123-133
- https://doi.org/10.1021/ar100112y
Abstract
Metal−organic frameworks (MOFs)—highly crystalline hybrid materials that combine metal ions with rigid organic ligands—have emerged as an important class of porous materials. The organic ligands add flexibility and diversity to the chemical structures and functions of these materials. In this Account, we summarize our laboratory’s experience in tuning the topology and functionality of MOFs by ligand design. These investigations have led to new materials with interesting properties. By using a ligand that can adopt different symmetry conformations through free internal bond rotation, we have obtained two MOFs that are supramolecular stereoisomers of each other at different reaction temperatures. In another case, where the dimerized ligands function as a D3-Piedfort unit spacer, we achieve chiral (10,3)-a networks. In the design of MOF-based materials for hydrogen and methane storage, we focused on increasing the gas affinity of frameworks by using ligands with different geometries to control the pore size and effectively introduce unsaturated metal centers (UMCs) into the framework. Framework interpenetration in PCN-6 (PCN stands for porous coordination network) can lead to higher hydrogen uptake. Because of the proper alignment of the UMCs, PCN-12 holds the record for uptake of hydrogen at 77 K/760 Torr. In the case of methane storage, PCN-14 with anthracene-derived ligand achieves breakthrough storage capacity, at a level 28% higher than the U.S. Department of Energy target. Selective gas adsorption requires a pore size comparable to that of the target gas molecules; therefore, we use bulky ligands and network interpenetration to reduce the pore size. In addition, with the help of an amphiphilic ligand, we were able to use temperature to continuously change pore size in a 2D layer MOF. Adding charge to an organic ligand can also stabilize frameworks. By ionizing the amine group within mesoMOF-1, the resulting electronic repulsion keeps the network from collapsing, giving rise to the first case of mesoporous MOF that demonstrates the type IV isotherm. We use dendritic hexacarboxylate ligands to synthesize an isoreticular series of MOFs with (3,24)-connected network topology. The cuboctahedral cages serve as building blocks that narrow the opening of the mesocavities into microwindows and stabilize these MOFs. The resulting materials have exceptionally high surface areas and hydrogen uptake capacities. Despite the many achievements in MOF development, there is still ample opportunity for further exploration. We will be continuing our efforts and look forward to contributing to this blossoming field in the next decade.Keywords
This publication has 42 references indexed in Scilit:
- An Isoreticular Series of Metal–Organic Frameworks with Dendritic Hexacarboxylate Ligands and Exceptionally High Gas‐Uptake CapacityAngewandte Chemie-International Edition, 2010
- Preparation and Gas Adsorption Studies of Three Mesh-Adjustable Molecular Sieves with a Common StructureJournal of the American Chemical Society, 2009
- Selective gas adsorption and separation in metal–organic frameworksChemical Society Reviews, 2009
- Microporous Lanthanide Metal-Organic Frameworks Containing Coordinatively Linked Interpenetration: Syntheses, Gas Adsorption Studies, Thermal Stability Analysis, and Photoluminescence InvestigationInorganic Chemistry, 2009
- A Coordinatively Linked Yb Metal–Organic Framework Demonstrates High Thermal Stability and Uncommon Gas‐Adsorption SelectivityAngewandte Chemie-International Edition, 2008
- Metal−Organic Framework Based on a Trinickel Secondary Building Unit Exhibiting Gas-Sorption HysteresisInorganic Chemistry, 2007
- Stability and Porosity Enhancement through Concurrent Ligand Extension and Secondary Building Unit StabilizationInorganic Chemistry, 2006
- Construction of Open Metal–Organic Frameworks Based on Predesigned Carboxylate Isomers: From Achiral to Chiral NetsChemistry – A European Journal, 2006
- (10,3)-a Noninterpenetrated Network Built from a Piedfort Ligand PairInorganic Chemistry, 2006
- Reticular synthesis and the design of new materialsNature, 2003