Solid-state transformations for clean and energy-efficient synthesis

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The proposed research develops highly efficient methods of chemical synthesis in the solid state as potential alternatives to conventional solvent-based procedures. The reactivity of interest is based on recently discovered and not yet fully understood catalytic effects that allow the transformations of inert inorganic materials (e.g. metal oxides or sulfides) into valuable products, including metallodrugs and porous metal-organic frameworks (MOFs), at rates comparable to or higher than those in conventional solution synthesis. Proposed methodologies will be low-energy and solvent-free, with potential to greatly reduce energy, solvent and materials costs of laboratory and industrial research. We will explain and develop novel "accelerated aging" reactions that use catalytic salt additives, aided by organic or water vapors, to fully convert inert precursors into products using little energy input and no solvent. These readily scalable reactions are targeted for potential applications in low-energy and solvent-free mineral manufacturing, metal extraction or nuclear waste sequestration. We will establish a rational understanding of recently discovered catalytic mechanosynthesis which provides valuable products under mild conditions and using significantly less energy and solvent than traditional solvothermal methods. The research program will be based on a systematic design of screening experiments which explore the scope and mechanisms of "accelerated aging" and mechanochemical reactions. Reaction screening will be coupled to a variety of cutting-edge diffraction, spectroscopy, microscopy and thermal analysis techniques for product characterization, stepwise reaction monitoring and real-time observation of reactions. In addition to rationalizing new and efficient modes of solid-state reactivity, mechanochemical screening will be used for the first systematic study of how topology, porosity and moisture sensitivity of MOFs are controlled in the absence of solution interferences. This research and training program will develop reversible covalent synthesis under mechanochemical conditions for the efficient synthesis of non-symmetrical molecules and room-temperature synthesis of porous covalent frameworks.