Mit Vorsicht zu handhaben: Der hochempfindliche Sprengstoff CL‐20 bildet durch Cokristallisation mit TNT einen neuartigen, wenig empfindlichen Hochleistungssprengstoff. Das cokristalline Material kann direkt als Sprengstoff verwendet oder in dieser unempfindlichen Form gelagert und durch Erwärmen wieder in seine hochempfindliche Form überführt werden.

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The potential for relatively minor structural changes to dramatically impact materials properties is one of the primary obstacles to achieving the rational design of functional materials. For example, having an odd versus an even number of carbons between functional groups in polymers can cause large variation in melting point and mechanical properties. This odd-even effect is especially pronounced in hydrogen-bonded polymers and oligomers. To shed light on the structural basis of this phenomenon, physisorbed monolayers and single crystals of alkyl dicarbamates were investigated by scanning tunneling microscopy and X-ray diffraction, respectively. The related two- and three-dimensional crystal structures both demonstrated a clear odd-even effect in packing geometry. The differing accommodation of intermolecular interactions between odd and even packing motifs was directly related to the melting point trends and further dissected through computation. In addition, these oligomers displayed unusual competitive adsorption behavior; the relative preference for adsorption of a smaller species from a binary solution was increased compared to alkanes. These results were explained in the context of hydrogen bond density effects that arise due to competition for a limited substrate surface area. This study provides a model for understanding oligourethane surface coatings and demonstrates the importance of molecular structure and hydrogen bonding in determining adsorption behavior.

A design strategy based on geometric analysis of linker shape and flexibility is developed in the context of achieving predictable topology of tetratopic-linker based Zr microporous coordination polymers (MCPs). Tetratopic linkers are categorized into tetrahedral, planar square, or planar rectangular groups based on symmetry with an emphasis on linker flexibility. A prediction framework solely based on linker shape and cluster connectivity derived from this strategy is applied to all 18 reported tetratopiclinker based Zr MCPs, and their determined topologies fit well into the scheme. Two new Zr MCPs (UMCM-312 and UMCM-313) are produced using designed linkers based on the strategy to test the robustness of prediction. UMCM-312 contains a biphenyl-core based tetratopic linker to target tetrahedral shape, and UMCM-313 takes advantage of a perylene based tetratopic linker to achieve rectangular shape. The experimentally determined topologies confirm predictions. It is thus demonstrated that the uncertainty of targeting topologies in tetratopic-linker based Zr MCPs can be reduced by accounting for linker shape and flexibility.