Logic and Symbolism of Switchable Porous Framework Materials

Metal-Organic Frameworks (MOFs) are highly porous materials composed of organic linkers connected by inorganic nodes. A unique subset of MOFs shows switchability, the ability to switch between at least two distinct structures differing significantly in porosity. These unique guest dependent pore opening and closing processes offer new opportunities in gas separation, selective recognition, sensing and energy storage. However, the factors affecting switchability are poorly understood. Network topology, micromechanics of building blocks and their hinges, but also particle size, defects, agglomeration, desolvation conditions etc. are convoluted into the responsiveness of the system.

In essence all factors are a consequence of the materials history including synthesis procedure and desolvation but also all subsequent handling steps such as mechanical and adsorption stress leading to a complex interplay of factors which are difficult to express clearly by ordinary writing systems, chemical or mathematical symbols without loss of intuitive understanding. Here we propose a symbolic language for the rationalization of switchability emphasizing the history dependent responsivity of many dynamic frameworks and their stimuli induced 1^st order phase transitions. Color representations of the guest and host offer an intuitive understanding of switchability phenomena even for non-experts. The system follows a bivalent logic inspired by Freges Begriffsschrift providing a fundamental logic structure for the rationalization of statements and representation of logic gates.