Development of novel constituents and architectures is essential for a fundamental understanding of the mechanisms involved in actinide integration inside extended structures necessary to optimize nuclear waste administration. Hybrid materials, such as metal-organic frameworks (MOFs), can be utilized as a foundation for the engineering of actinide-containing materials. The unprecedented modularity of MOFs can address current challenges for efficient storage, separation and selective sequestration of nuclear waste.
In this work, we applied a sequential multi-step approach towards actinide immobilization through utilization of the modularity and versatility of MOFs, which cannot be replicated in any other type of materials. The first examples of actinide-based MOFs with “unsaturated” metal nodes necessary for the further building of hierarchical complexity of actinide-containing materials were prepared. As a result, actinide-bimetallic MOFs were prepared through metal node extension and transmetallation for the first time. Through a combination of solid-state metathesis, guest incorporation, and capping linker installation, we were able to achieve the highest Th wt% in MOFs with minimal structural density. Overall, the role of framework modularity towards stepwise actinide incorporation inside extended structures was demonstrated, which is essential for more efficient nuclear waste management.