Anhydride Post-Synthetic Modification in a Hierarchical Metal–Organic Framework

Abstract

Metal–organic frameworks (MOFs) are important porous materials. Post-synthetic modification (PSM) of MOFs via the pendant groups or secondary functional groups of organic linkers has been widely used to introduce new or enhance existing properties of MOFs for various practical applications. In this work, we have constructed, for the first time, a novel platform for PSM of MOFs by introducing an anhydride functional group into a hierarchically porous MOF (MIL-121) as an effective anchor. We have demonstrated that the combination of the high reactivity of anhydride and hierarchical porosity makes this protocol particularly novel and important, as it led to excellent opportunities of incorporating not only a wide variety of organic molecules with different sizes and chemical nature but also the noble metal complexes in MOFs. Specifically, we show that the anhydride group decorated in the MOF exhibits a high reactivity toward covalently binding 10 different guest molecules including alcohols, amines, thiols, and noble metal (Pt­(II)/Pt­(IV)) complexes, whereas the hierarchical pores created in the MOF allow the incorporation of guest species varying in size from methanol to larger molecules such as polyaromatic amines. This novel approach provides the community with a new avenue to prepare MOF-based materials for targeted applications. To illustrate this point, we furnish an example of using this new platform to prepare a Pt-based electrocatalyst which shows excellent catalytic activity toward the oxygen reduction reaction (ORR), a pivotal half-reaction in hydrogen–oxygen fuel cells and other energy storage and conversion devices.

Post‐Synthetic Modification of Metal–Organic Frameworks Toward Applications

“…The resultant product is useful in trapping organic guest molecules of a wider size range and the metal ions. [ 73 ]…”

Hydrothermal Approach for Reticular Synthesis of Coordination Assemblies with Dicarboxylatotetramethyldistannoxanes as the Secondary Building Units

“…Notably, the presence of anhydride group offers further possibilities to introduce new functionalities via post‐chemical modification approach. [ 18 ]…”

Two‐Dimensional Metal‐Organic Frameworks and Covalent Organic Frameworks

“…Huang et al . [ 33 ] used the acid anhydride group in the MOF as a covalent reaction site to covalently introduce Pt ions to obtain an electrocatalyst material (Pt‐HMIL‐121‐900) containing highly dispersed Pt nanoparticles. In the electrochemical oxygen reduction, the catalyst exhibited a catalytic activity twice higher than that of commercial Pt/C (40 wt%).…”