Introducing functionalities into directly synthesised amorphous UiO-66-based metal-organic frameworks

Abstract

We report a scalable and environmentally benign methodology for the direct, water-based synthesis of porous amorphous UiO-66–type metal–organic frameworks (aMOFs), conducted at room temperature and enabling the incorporation of a wide range of functionalised linkers without organic solvents. Pair distribution function (PDF) analysis demonstrates that the amorphous frameworks largely retain the local structural motifs of their crystalline analogues, with minor short-range distortions arising from changes in Zr-cluster geometry and linker binding modes. Thermogravimetric analysis indicates a high density of missing-linker defects and dangling linker sites, characteristic of the disordered structure. The aMOFs exhibit catalytic activities comparable to or exceeding those of the crystalline materials in the esterification of levulinic acid, while the structural disorder enhances stability and recyclability under harsh conditions. This work illustrates how green, water-based synthetic strategies can produce functional, porous, and highly active amorphous MOFs, offering a sustainable and versatile approach for the development of industrially relevant catalytic materials.