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Creators/Authors contains: "Swenson, Dale C."

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  1. null (Ed.)
    Photoirradiation of a binary cocrystal composed of two different cyclic dienes generates a highly-symmetric cubane-like tetraacid cage regioselectively and in quantitative yield. The cage forms by a double [2+2] photodimerization of one of the diene cocrystal components. The second diene while photostable in the cocrystal reacts in a double [2+2] photodimerization as a pure form quantitatively to form a tetramethyl cubane-like cage. The stereochemistry of the cage is structurally authenticated. 
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  2. We describe hydrogen bonds ( i.e. , N + –H⋯N) in combination with cation⋯π interactions to enable a cascade-like [2 + 2] photodimerization of 4-stilbazole in a salt cocrystal. A four-component crystal assembly is composed of photoactive pyridinium ion pair 4-stilbzH + ( 4-stilbz = trans -1-(4-pyridyl)-2-(phenyl)ethylene) and photostable molecule pair 4-stilbz . UV irradiation gives rctt -1,2-bis(4-pyridyl)-3,4-bis(phenyl)cyclobutane ( 4-pyr-ph-cb ) in quantitative yield. An intermediate structure 2 ( 4-stilbz )·( 4-pyr-ph-cb )2H + is isolated that undergoes a partial single-crystal-to-single-crystal transformation. The single-crystal X-ray data provides a snapshot of movements in the salt cocrystal in the course of the photodimerization. 
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  3. Abstract

    A method to rapidly diversify the molecules formed in organic crystals is introduced, with aryl nitriles playing a novel dual role as both hydrogen‐bond acceptors and modifiable organic groups. The discovery of coexisting supramolecular synthons in the same crystal is also described. The general concept is demonstrated by using a bis(aryl nitrile) alkene that undergoes a hydrogen‐bond‐directed intermolecular [2+2] photodimerization to form a tetra(aryl nitrile)cyclobutane. The product is readily converted by click reactivity to a tetra(aryl tetrazole) and by hydrolysis to a tetra(aryl carboxylic acid). The integration of aryl nitriles into solid‐state reactions opens broad avenues to post‐modify products formed in crystalline solids for rapid diversification.

     
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  4. Soft porous nanocrystals with a pronounced shape-memory effect exhibit two- to three-fold increase in elastic modulus compared to the microcrystalline counterpart as determined by atomic force microscopy nanoindentation. The increase in rigidity is consistent with the known shape-memory effect displayed by the framework solid at the nanoscale. Crystal downsizing can offer new avenues for tailoring the mechanical properties of metal–organic frameworks. 
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  5. null (Ed.)
    We describe the integration of a small-molecule hydrogen-bond-donor template into a cascade reaction that is comprised of a combination of molecular and supramolecular events. The cascade is performed mechanochemically and in the presence of μL amounts of water. The small-molecule template is generated (molecular) using water-assisted vortex grinding and is then used to assemble an alkene (supramolecular) to undergo an intermolecular [2 + 2] photodimerization reaction (molecular). The chemical cascade results in a cyclobutane photoproduct that we show serves as a building block of a hydrogen-bonded network with a topology that conforms to T-silica. Remarkably, the molecular–supramolecular–molecular chemical cascade occurs stepwise and entirely regioselectively within the continuous mechanochemical conditions employed. 
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  6. null (Ed.)
    We report supramolecular repurposing of emtricitabine (FTC, trade name: Emtriva®), a blockbuster FDA-approved anti-HIV agent. FTC is revealed to act as a hydrogen-bonded cleft for bipyridine recognition. The supramolecular repurposing is realized by the generation of four cocrystals through liquid-assisted grinding. The clefts comprise discrete three-component assemblies sustained by a combination of hydrogen bonds and π⋯π interactions. 
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