Multicomponent Metal–Organic Frameworks as Defect-Tolerant Materials

Abstract

Multicomponent metal-organic frameworks (MOFs) comprise multiple, structurally diverse linkers fixed into an ordered lattice by metal ions or clusters as secondary building units (SBUs). Here, we show how multicomponent MOFs are ideal platforms for engineering materials with high levels of vacancy defects. First, a new type of quaternary MOF that is built up from two neutral, linear ditopic linkers, a 3-fold-symmetric carboxylate ligand, and a dinuclear paddlewheel SBU was synthesized. This MOF, named MUF-32 (MUF = Massey University Framework), is constructed from dabco, 4,4′-bipyridyl (bipy), 4,4′,4″-nitrilotrisbenzoate (ntb), and zinc(II), and it adopts an ith-d topology. The zinc(II) ions and ntb ligand define an underlying [Zn2(ntb)4/3] sublattice (with pto topology) that is "load bearing" and maintains the structural integrity of the framework. On the other hand, the dabco and bipy ligands are "decorative", and high levels of vacancy defects can be introduced by their partial omission or removal. These defects can be generated by direct synthesis or by postsynthetic modification. The framework structure, crystallinity, and porosity are maintained even when vacancy levels of 80% are reached. Defect healing is possible by introducing free ligands in a solvent-assisted process to restore pristine MUF-32. Computational analysis reveals that the mechanical instability of the [Zn2(ntb)4/3] sublattice sets an upper limit on defect levels in this material. Multicomponent Metal-Organic Frameworks as Defect-Tolerant Materials Seok J. Lee, [a] Celine Doussot, [a] Anthony Baux, [a] Lujia Liu, [a] Geoffrey B. Jameson, [a] Christopher Richardson, [b] Joshua J. Pak, [c] Fabien Trousselet, [d] Francois-Xavier Coudert, [d] Supporting Information PlaceholderABSTRACT: Multicomponent metal-organic frameworks (MOFs) comprise multiple, structurally-diverse linkers fixed into an ordered lattice by metal ions or clusters as secondary building units (SBUs). Here, we show how multicomponent MOFs are ideal platforms for engineering materials with high levels of vacancy defects. First, a new type of quaternary MOF that is built up from two neutral, linear ditopic linkers, a threefold-symmetric carboxylate ligand, and a dinuclear paddlewheel SBU was synthesized. This MOF, named MUF-32 (MUF = Massey University Framework), is constructed from dabco, 4,4'-bipyridyl (bipy), 4,4',4''-nitrilotrisbenzoate (ntb) and zinc(II), and it adopts an ith-d topology. The zinc(III) ions and ntb ligand define an underlying [Zn 2 (ntb) 4/3 ] sublattice (with pto topology) that is 'load bearing' and maintains the structural integrity of the framework. On the other hand, the dabco and bipy ligands are 'decorative' and high levels of vacancy defects can be introduced by their omission. These defects can be generated by direct synthesis or by postsynthetic modification. The framework structure, crystallinity and porosity are maintained even when vacancy levels of 80% are reached. Defect healing is possible by introducing free ligands in a s...

Defective Metal‐Organic Frameworks

“…Similar to the de novo approach reported by Kozachuck et al, SALE also enables the introduction of linkers with different coordination sites, thereby modifying the electronic state of the metal node. Additionally, there are reports where MOF ligands are exchanged by solvent molecules itself (DMF) due to the ability of the solvent to coordinate to CUS as shown by Lee et al Likewise, the solvent‐assisted ligand incorporation (SALI) allows for manipulating the functionality of the metal node with leaving the linker of the framework untouched . For instance, Deria et al used different perfluorinated carboxylic acids coordinating to vacant sites at the node to increase the hydrophobicity of NU‐1000 and its CO 2 capture ability.…”

“…Therefore, the framework must provide tolerance to such defects in order to maintain its stability. An interesting case facing this problem was reported by Lee et al (see Figure ) . The authors report on MUF‐32 (Massey University Framework), which is built from Zn paddle wheel (PW) units as SBU, 4,4′,4″‐nitrilotrisbenzoate (ntb) as the tritopic organic linker and two neutral N‐donor ligands 1,4‐diazabicyclo[2.2.2]octane (dabco) and 4,4′‐bipyridine (bipy), spanning a 3D net in the ith‐d topology.…”

“…Formation of vacancy defects in MUF‐32, whereby the structural pto sublattice is preserved. Reproduced with permission . Copyright 2016, American Chemical Society.…”

Enhancing Multicomponent Metal–Organic Frameworks for Low Pressure Liquid Organic Hydrogen Carrier Separations

“…Multicomponent MOFs have emerging applications in catalysis, luminescence and gas storage . In order to form multicomponent MOFs judicious selection of the linkers is essential (Figure , Scheme S1) .…”

Enhancing Multicomponent Metal–Organic Frameworks for Low Pressure Liquid Organic Hydrogen Carrier Separations

“…Multicomponent MOFs have emerging applications in catalysis, luminescence and gas storage . In order to form multicomponent MOFs judicious selection of the linkers is essential (Figure , Scheme S1) .…”