A Mesoporous Zirconium-Isophthalate Multifunctional Platform

Abstract

Mesoporous materials suffer from limitations including poor crystallinity and hydrolytic stability, lack of chemical diversity, insufficient pore accessibility, complex synthesis and toxicity issues. Here the association of non-toxic Zr-oxo clusters and feedstock isophthalic acid (IPA) via a Homometallic-Multicluster-Dot strategy results in a robust crystalline mesoporous MOF, denoted as MIP-206, that overcomes the aforementioned limitations. MIP-206, built up from an unprecedented combination of Zr6 and Zr12 oxo-cluster inorganic building units into a single structure, exhibits accessible meso-channels of ca. 2.6 nm and displays excellent chemical stability under different hydrolytic and harsh conditions. Owing to the abundant variety of functionalized IPA linkers, the chemical environment of MIP-206 can be easily tuned without hampering pore accessibility due to its large pore windows. As a result, MIP-206 loaded with palladium nanoparticles acts as an efficient and durable catalyst for the dehydrogenation of formic acid under mild conditions, outperforming benchmark mesoporous materials. This paves the way towards the utilization of MIP-206 as a robust mesoporous platform for a wide range of potential applications. Mesoporous solids, a category of materials possessing structural voids of 2-50 nm in which large guest molecules can be accommodated, are of interest to sustainable development with potentially broad applications in fields related to energy, environment and health. Owing to their high availability and tunable pore size, traditional mesoporous materials, such as silica, metal oxides and activated carbons, are prevalent in current usage, particularly in heterogeneous catalysis 1 , energy conversion/storage 2 , analytical science 3 and medical areas 4 , although they suffer from well-recognized limitations such as lack of crystallinity, chemical diversity, structural uniformity, stability and/or reproducibility. These limitations have inhibited pursuits to improve their performance, extend their use to other applicable fields and accumulate fundamental understanding 5 of these materials. Considerable efforts have been devoted in the past two decades to develop substitutes, promote new strategies and develop alternative candidates 6. Among them, mesoporous metal-organic frameworks (MOFs) are a promising family of materials that exhibits an ordered porosity and successfully addresses some limitations of conventional benchmarks. MOFs can be composed of an almost unlimited selection of inorganic building blocks (metal ions or clusters) and organic linkers in periodic structures which are merged efficiently, exhibiting high crystallinity with atomic precision, good reproducibility of preparation over control, and, most importantly, remarkable structural and chemical tunability 7; 8. Two strategies for preparing mesoporous MOFs are well-documented. Extending the organic linker to construct mesoporous MOFs following the isoreticular chemistry strategy is the most straightforward route and illustrates well the...

Clip‐off Chemistry: Synthesis by Programmed Disassembly of Reticular Materials**

“…We expected that this first clip‐off reaction would afford the first‐ever example of a 3D MOF made of archetypical Zr‐oxo‐hydroxo‐clusters linked by isophthalate‐like linkers in a pcu underlying net. Interestingly, the closest literature example of such a structure is that of a 2D MOF made of Zr‐oxo‐hydroxo‐clusters linked by isophthalate, albeit in an hcb topology [29] . Our target 3D Zr‐ pcu MOF could also be seen as exemplifying a connection of Zr‐oxo‐hydroxo‐clusters through trimesate linkers, which are coordinated only through two of their three carboxylate groups.…”

Clip‐off Chemistry: Synthesis by Programmed Disassembly of Reticular Materials**

“…Interestingly,t he closest literature example of such astructure is that of a2DMOF made of Zroxo-hydroxo-clusters linked by isophthalate,a lbeit in an hcb topology. [29] Our target 3D Zr-pcu MOF could also be seen as exemplifying ac onnection of Zr-oxo-hydroxo-clusters through trimesate linkers,which are coordinated only through two of their three carboxylate groups.A ccordingly,i tc ould also be considered as the first example of aZr-structure with af ree carboxylic acid using trimesate,a sr esearchers have previously reported combination of Zr-oxo-hydroxo-clusters with this linker in a spn topology of 3,6-connectivity. [30] We synthesized colorless cubic crystals of isoreticular Zrscu-MOF by solvothermal reaction (120 8 8C) of am ixture of ZrOCl 2 •8 H 2 Oand L 2 in N,N-dimethylformamide (DMF) and formic acid for 5days.T he crystal structure revealed the expected isoreticular scu framework, in which L 1 had been replaced by L 2 (Figure 2a;s ee Supporting Information (SI), section S2).…”

Clip-off Chemistry: Synthesis by Programmed Disassembly of Reticular Materials

“…We expected that this first clip-off reaction would afford the first-ever example of a 3-D MOF made of archetypical Zr-oxo-hydroxo-clusters linked by isophthalate-like linkers in a pcu underlying net. Interestingly, the closest literature example of such a structure is that of a 2-D MOF made of Zr-oxo-hydroxo-clusters linked by isophthalate but in an hcb topology (29). Our target 3-D Zr-pcu MOF could also be seen as exemplifying a connection of Zr-oxohydroxo-clusters through trimesate linkers, which are coordinated only through two of their three carboxylate groups.…”