Coordination Funds

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Porous materials play a key role for gas and liquid phase separation, energy storage, as catalysts and for optical and chemical sensing. Metal-Organic Frameworks (MOFs) stand out among other porous materials due to their extremely high porosity and modular tunability. While the majority of porous solids (and MOFs) is rigid, a unique class of switchable MOFs offers unexpected flexibility. These materials open their pores dynamically, as a response to the presence of gases or liquids associated with unprecedented, step-wise structural transformations. They are able to specifically respond or even recognize distinct molecular species by opening their pores, resulting in a step-wise change of physical properties (i.e. magnetism, optical density, bulk density, etc.) and chemical characteristics (catalytic activity, reactivity). So far the discovery of switchable MOFs (also named “gating”, or “breathing” MOFs) was essentially accidental and it is impossible to rationally predict new switchable structures, because the underlying microstructural principles, are not well understood. For the technological development of switchable MOFs in separation, catalysis, or sensing, a fundamental understanding of the underlying structural principles and gas-solid interaction mechanisms is needed. The research unit primarily addresses the fundamentals of porosity switching phenomena in the solid state and the underlying principles. Targeting idealized model materials, the role of network constituents, defects, and cooperativity on the degree of flexibility is studied in a collaborative and closely coordinated experimental and theoretical approach.Based on the fundamental understanding developed, the research unit will explore generic functions of switchable MOFs in the 2nd funding phase. Highly selective molecular separation is targeted with switchable porous frameworks opening their pores ideally for only one molecular species. Such unique behavior plays an important role in industrial separation processes or the recognition of complex molecules. The integration of catalytically active guest-species into switchable frameworks will enable to switch these catalysts “on” by an external trigger. An interdisciplinary effort in a focused research unit, fostering an intense cooperation of theoreticians, synthetic chemists, and physicists, provides the ideal structure required to develop such selective recognition concepts for switchable porous frameworks from in silico prediction to the final experimental realization of switchable catalysts and highly selective separation processes.