Identification of a metastable uranium metal-organic framework isomer through non-equilibrium synthesis

Since the structure of supramolecular isomers determines their performance, rational synthesis of a specific isomer hinges on understanding the energetic relationships between isomeric possibilities. To this end, we have systematically interrogated a pair of uranium-based metal-organic framework topological isomers both synthetically and through density functional theory (DFT) energetic calculations. Although synthetic and energetic data initially appeared to mismatch, we assigned this phenomenon to the appearance of a metastable isomer, driven by levers defined by Le Chatelier's principle. Identifying the relationship between structure and energetics in this study reveals how non-equilibrium synthetic conditions can be used as a strategy to target metastable MOFs. Additionally, this study demonstrates how defined MOF design rules may enable access to products within the energetic phase space which are more complex than conventional binary (e.g., kinetic vs. thermodynamic) products.

Automated summary

The structure of supramolecular isomers determines their performance and rational synthesis relies on understanding the energetic relationships between them. A study on uranium-based metal-organic framework topological isomers revealed the existence of metastable isomers and the influence of non-equilibrium synthetic conditions. Furthermore, the study demonstrated that defined MOF design rules can lead to the synthesis of more complex products.