Metal‐Organic Frameworks: Aluminium‐Based Frameworks

Abstract

Metal–organic frameworks (MOFs) containing light and environmentally benign metals have attracted researchers from industry and academia since they are believed to be well suited for applications especially in the field of gas storage. Aluminum is one element of choice for the synthesis of such MOFs since it leads to stable and highly porous materials that can also be formed in water as a green solvent. The stability and the small number of Al‐based MOFs stems from the same factors: the high charge (+3) of the metal ion and the small ionic radius. Hence dissolution of these MOFs in water is often kinetically hindered and at the same time they are almost exclusively obtained as microcrystalline products. The latter fact has impeded the structure elucidation and the determination of structure property relationships and hence the intensive investigation of this class of compounds. Recent progress in the synthesis and characterization of Al‐MOFs has demonstrated that certain structural motifs are predominantly observed, depending on the substitution pattern of the polycarboxylate based linker molecules and the solvent employed. Here, the synthesis and structural trends in Al‐based MOFs are summarized.

SO2 Capture by Two Aluminum-Based MOFs: Rigid-like MIL-53(Al)-TDC versus Breathing MIL-53(Al)-BDC

“…At the initial stage of adsorption, SO 2 was found to interact via its O-atoms with the H-atom of the μ-OH group of MIL-53­(Al)-TDC with a mean separating distance of 2.05 Å, as defined by the radial distribution function (RDF) plotted for the corresponding atom pair in Figure S22. Such scenario that remains valid at higher SO 2 loading corresponds to relatively strong host/guest interactions, which is reminiscent with what we already reported for SO 2 in other MOFs containing hydroxyl groups. , In addition, the SO 2 molecules establish additional weaker interactions with the aromatic rings through their oxygen atoms, with mean separating distances of about 3.5 Å. At higher loading, the SO 2 molecules interact with each other with a mean separating distance of about 3.34 Å (Figure S22).…”

Microwave-Assisted Synthesis of Nanoporous Aluminum-Based Coordination Polymers as Catalysts for Selective Sulfoxidation Reaction

“…In this regard, aluminum-based MOFs (Al–MOFs) are considered to be one of the better choices because of their high stability and porosity [ 1 , 2 , 3 , 4 , 5 ]. In addition to the large abundance of Al source, the low cost and less toxic nature of aluminum leads the chemistry of Al based MOFs to be of special interest [ 6 ]. In particular, MIL-100 [ 4 ], MIL-53 [ 2 ] and the isoreticular MOFs of MIL-53, such as DUT-4 [ 1 ], DUT-5 [ 1 ], and NH 2 -MIL-53 [ 3 ], have been investigated for their unique structural properties and potential applications [ 3 , 7 , 8 , 9 ].…”

Synthesis, Structure, and Selected Properties of Aluminum-, Gallium-, and Indium-Based Metal-Organic Frameworks

“…Similar to aluminum, Ga 3+ can also form condensed polyoxogallate clusters (Ga 13 ) [31,32], and also dimers of corner-sharing tetrahedra [Ga 2 O(OH) 6 ] 2− have been observed [33]. In its complexes it is mostly found as isolated GaO 4 and GaO 6 polyhedra depending on the pH of the solution. The aqueous chemistry of In 3+ is dominated by isolated [In(H 2 O] 6 ] 3+ complexes, and condensed clusters are rarely found [34].…”

“…MO 4 and chains of trans-and cis-corner-sharing octahedra are well known for aluminum, gallium, and indium (Figure 5.3; III and IV, e.g., in MIL-100 [49], MIL-53 [12], and CAU-10 [50], respectively). Zigzag chains of edge-sharing octahedra have been observed for Al-and Ga-MOFs, for example, in MIL-120 [51,52].…”