Publication
Metal-organic frameworks (MOFs), or coordination polymers (CPs), are networks of organic ligands and metal nodes that form ordered or disordered structures. By selecting appropriate building blocks, CPs with tailored pore shapes, dimensions, and surface chemistry can be designed for applications such as separations and catalysis. Traditionally, MOF research has focused on crystalline structures due to their well-defined atomic arrangements. However, stability - often determined by how crystalline a material remains under operation conditions - remains a major challenge for commercial applications. This work explores the potential of amorphous MOFs, showing that a focus on the local structure, which extends only a few Angstrom, offers new insights for material engineering. The first part introduces the motivation for the local structure perspective on MOFs. We present a strategy to post-synthetically modify polymer chains within MOF pores for selective precious metal adsorption and reduction. While promising, stability concerns arose under application-relevant conditions. However, despite significant crystallinity loss, the composite retained functionality, challenging the necessity of highly crystalline starting materials. In the following part, we examine amorphous and disordered CPs as alternatives to crystalline MOFs. We apply the local-structure perspective to Zr-based MOFs. Zr-MOFs are ideal due to extensive research on their discrete Zr oxo clusters independent from research on MOFs. We demonstrate that amorphous Zr-MOFs can be engineered to induce oxygen vacancies, generating coordinatively unsaturated Zr (Zr-cus) sites. These lower-symmetry structures, identifiable only through local structure analysis, enhance catalytic and water purification performance by increasing Zr-cus site density. Next, we extended our focus to the direct synthesis of amorphous CPs. We found that highly stable, porous, Zr organophosphate structures can be synthesized using environmentally friendly conditions and bio-available building blocks. The resulting CP shows excellent performance metrics for selectively removing toxic lead from water. Here, too, the local structure perspective is a useful tool for characterizing the material and assessing its stability in various application-relevant conditions. Finally, we assess method protocols to characterize the local structure using widely available laboratory instruments. This study highlights the advantages of amorphous MOFs, demonstrating that their properties can be tuned via local structure engineering. They can be synthesized with low energy input, characterized effectively, and optimized for applications such as catalysis and water remediation.