Materials with surfaces that can be switched from high/superhydrophobicity to superhydrophilicity are useful for myriad applications. Herein, we report a metal-organic framework (MOF) assembled from Zn ions, 1,4-benzenedicarboxylate, and a hydrophobic carborane-based linker. The MOF crystal-surface can be switched between hydrophobic and superhydrophilic through a chemical treatment to remove some of the building blocks.
A well-established strategy to synthesize heterogeneous, metal-organic framework (MOF) catalysts that exhibit nanoconfinement effects, and specific pores with highly-localized catalytic sites, is to use organic linkers containing organocatalytic centers. Here, we report that by combining this linker approach with reticular chemistry, and exploiting three-dimensioanl (3D) MOF-structural data from the Cambridge Structural Database, we have designed four heterogeneous MOF-based catalysts for standard organic transformations. These programmable MOFs are isoreticular versions of pcu IRMOF-16, fcu UiO-68 and pillared-pcu SNU-8X, the three most common topologies of MOFs built from the organic linker p,p'-terphenyldicarboxylic acid (tpdc). To synthesize the four squaramide-based MOFs, we designed and synthesized a linker, 4,4'-((3,4dioxocyclobut-1-ene-1,2-diyl)bis(azanedyil))dibenzoic acid (Sq_tpdc), which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers. Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena. Therefore, the four MOFs share the same organocatalytic squaramide moiety, but confine it within distinct pore environments. We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations: a Friedel-Crafts alkylation and an epoxide ring-opening. Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences.
Materials with surfaces that can be switched from high/superhydrophobicity to superhydrophilicity are useful for myriad applications. Herein, we report a metal–organic framework (MOF) assembled from ZnII ions, 1,4‐benzenedicarboxylate, and a hydrophobic carborane‐based linker. The MOF crystal‐surface can be switched between hydrophobic and superhydrophilic through a chemical treatment to remove some of the building blocks.
Tandem and multicomponent one‐pot reactions are highly attractive because they enable synthesis of target molecules in a single reaction vessel. However, they are difficult to control, as they can lead to the formation of many undesired side‐products. Herein we report the use of metal‐organic framework (MOF) pores decorated with organocatalytic squaramide moieties to confine ring‐opening epoxide reactions of diverse substrates. Controlled mono‐addition or tandem reactions inside the pores yield 1,2‐aminoalcohols or 1,2,2′‐aminodialcohols, respectively, in good yields. In addition, this squaramide‐functionalised MOF enables catalysis of higher‐complexity multicomponent reactions such as the catalytic ring‐opening of two different epoxides by a single amine to afford 1,2,2′‐aminodialcohols.
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