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Thermosalience in an anthracene-thiocarboxamide occurs due to strong anisotropic thermal expansion, and the solid responds uniquely to different external stimuli.

 

Developing an atomistic understanding of ionizing radiation induced changes to organic materials is necessary for intentional design of greener and more sustainable materials for radiation shielding and detection. Cocrystals are promising for these purposes, but a detailed understanding of how the specific intermolecular interactions within the lattice upon exposure to radiation affect the structural stability of the organic crystalline material is unknown. This study evaluates atomistic‐level effects of γ radiation on both single‐ and multicomponent organic crystalline materials and how specific noncovalent interactions and packing within the crystalline lattice enhance structural stability. Dose studies were performed on all crystalline systems and evaluated via experimental and computational methods. Changes in crystallinity were evaluated by p‐XRD and free radical formation was analyzed via EPR spectroscopy. Type of intermolecular interactions and packing within the crystal lattice was delineated and related to the specific free radical species formed and the structural integrity of each material. Periodic DFT and HOMO‐LUMO surface mapping calculations provided atomistic‐level identifications of the most probable sites for the radicals formed upon exposure to γ radiation and relate intermolecular interactions and molecular packing within the crystalline lattice to experimental results.

 

The realization of a pair of photoreactive polymorphic co-crystals that are held together by the combination of I⋯N halogen bonding interactions and C–H⋯Cl contacts is reported. The reactant molecule within these co-crystals is based upon an unsymmetrical olefin, namely 4-stilbazole, that results in a regioselective solid-state [2 + 2] cycloaddition reaction in both polymorphic forms. Each solid undergoes a quantitative photoreaction which yields exclusively the head-to-tail photoproduct.