While the production, stockpiling, and use of chemical weapons and their precursors is banned by the Chemical Weapons Convention, there are still recent reports of their employment in battlefields. Therefore, it is essential to develop materials that can efficiently capture and/or destroy chemical warfare agents (CWAs), such as sulfur mustard and organophosphonate-based nerve agents. Metal–organic frameworks (MOFs), a class of functional hybrid crystalline porous materials, offer a great platform for designing materials for targeted applications. We have recently demonstrated that the stable and functional Zr-based MOFs can effectively catalyze the hydrolysis of nerve agents via the Zr6 node, while the use of a photoactive linker can facilitate the oxidation of mustard gas using LED light. Importantly, we have also developed systems that can simultaneously destroy multiple agents. In addition, MOFs with large mesopores have been shown to act as support materials to provide long term stability for enzymes which catalyze the detoxification of the organophosphonate-based nerve agents in water and potentially for other applications as well. Nevertheless, MOFs are typically synthesized in high boiling point organic solvents (most commonly in DMF, DEF and DMSO) at or above 100 °C. These harsh conditions can hinder techno-economic access to materials of interest, such as enzyme/MOF composites, MOF/fiber composites, and large-scale production of MOFs. Herein, we propose to investigate fundamental design rules to access hydrochemically stable MOFs with various functionalities and diverse topologies using water as a solvent at room temperature. To do so, we will explore the effect of the modulator, a competing monotopic acid, on the purity and crystallinity of the final product. Additionally, several methods will be examined to increase the solubility of multitopic linkers with extended conjugation in order to access MOFs with various topologies. In addition to carboxylic acid based linkers, strategies for building MOFs with phosphoric acid based linkers will be investigated; this will allow us to obtain MOFs with enhanced stability compared to their carboxylic acid based analogues. Once these strategies are developed for the synthesis of highly stable MOFs in water at room temperature, we will be able to encapsulate heat-sensitive materials such as enzymes and nanoparticles which commonly encounter deformation under excessive heat or in organic medium. Lastly, using water as a solvent, we will integrate the stable MOFs on fibers as protective layers.
|Effective start/end date||8/1/19 → 7/31/22|
- Army Research Office (W911NF1910340)