Thinking Outside the Energetic Box: Stabilizing and Greening High-Energy Materials with Reticular Chemistry

Abstract

Conspectus Reticular chemistry has provided intriguing opportunities for systematically designing porous materials with different pores by adjusting the building blocks. Among them, framework materials have demonstrated outstanding performance for the design of new functional materials used in a broad range of fields, including energetic materials. Energetic materials are widely used for rockets, satellites, mining, and tunneling. In terms of energetic materials, explosophores and nitrogen-rich heterocycles are fundamental building blocks for high-energy compounds. However, the traditional strategy of synthesizing HEDMs (high energy density materials) at the molecular level has faced the long-term challenge of balancing energy and stability. Inspired by reticular chemistry, nitrogen-rich heterocycles offer diverse nitrogen sites for designing diversified coordination interactions. Ionic bond interactions exist in a wide range of energetic salts. Furthermore, most metastable explosophores, e.g., nitro, nitramino, and amino groups, can form strong hydrogen-bonding networks. Based on these noncovalent interactions (such as coordination, ionic, and/or hydrogen bonds (HBs)) and/or covalent interactions can determine intermolecular packing/linkage of the energetic fuel and oxidizer components, reticular chemistry provides a new platform evolving from single-molecular design to various energetic frameworks (E of the energetic frameworks with superior comprehensive properties. For example, to achieve coordination with metals or introduce sufficient hydrogen bond donor/acceptor structural units, the host structure of energetic framework materials usually contains less oxygen-rich substituents such as nitro, so the host molecules of the framework, F) at the crystal level, which can enhance the integrated stabilities of EFs. Along with growing concerns about the environment and safety issues, considerable effort has been devoted to pursuing environmentally friendly and insensitive energetic materials. The newly emerging EFs are conducive to introducing explosophores into a green chemical pathway. Benefiting from these cross-disciplinary achievements, taming metastable energetic molecules in specific porous frameworks is a green strategy to desensitize energetic materials while concomitantly retaining excellent energetic properties, which has become one of the most forward and promising investigations. In the past decade, EFs have achieved further results in stabilizing and greening energetic materials using HBs, covalent bonds, and alkaline earth metal-involving coordination bonds to avoid heavy metal toxicity and to employ halogen-free oxidizers. Because this field is still expanding rapidly, it is of great value for researchers and possible users of the work to be able to view all the progress. Through this Account, we intend that more readers will become knowledgeable about EFs, including their definition, history, synthesis, properties, and possible applications. The aim of this Account is to present the latest advances...