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Abstract Understanding photoreaction dynamics in crystals is important for predicting the dynamic property changes accompanying these photoreactions. In this work, we investigate the photoreaction dynamics ofp‐phenylenediacrylic acid dimethyl ester (p‐PDAMe) in single crystals that show reaction front propagation, in which the photoreaction proceeds heterogeneously from the edge to the center of the crystal. Moreover, we find thatp‐PDAMesingle crystals exhibit a distinctive crystal shape change from a parallelogram to a distorted shape resembling a fluttering flag, then to a rectangle as the photoreaction proceeds. Density functional theory calculations predict the crystal structure after the photoreaction, providing a reasonable explanation of the distinctive crystal shape change that results from the spatially heterogeneous photoreaction. These results prove that the spatially heterogeneous photoreaction dynamics have the ability to induce novel crystal shape changes beyond what would be expected based on the equilibrium reactant and product crystal shapes. 

Abstract Ruthenium‐catalyzed butadiene‐mediated benzannulation enabled the first synthesis of 3,10‐(di‐tert‐butyl)rubicene and its N‐doped derivatives as well as preliminary studies on their photophysical properties. Unlike the parent rubicene and 3,10‐(di‐tert‐butyl)rubicene, which adopt classical herringbone‐type packing motifs in the solid state, the N‐doped congener7 bdisplayed columnar packing with an alternating co‐facial arrangement of aromatic and heteroaromatic substructures. 

Abstract Solid‐state triplet–triplet annihilation upconversion (TTAUC) blue emission in an electroluminescence device (i.e., an organic light‐emitting diode (OLED)) is demonstrated. A conventional green fluorophore, tris‐(8‐hydroxyquinoline)aluminum (Alq₃), is employed as the sensitizer that generates 75% triplet under electrical pumping for the blue triplet–triplet annihilation emitter, 9,10‐bis(2′‐naphthyl) anthracene (ADN), with the heterojunction bilayer structure. The operation lifetime is elongated both for ADN blue (4.1x) and Alq₃green (34.8%) emission due to efficient use of excitons and separation of recombination and emission zone. To reduce the singlet quenching (SQ) of blue TTAUC signal by the Alq₃sensitizer with lower bandgap, 1‐(2,5‐dimethyl‐4‐(1‐pyrenyl)phenyl)pyrene (DMPPP) is inserted between the Alq₃and ADN as a triplet‐diffusion‐and‐singlet‐blocking layer. DMPPP exhibits triplet energy close to Alq₃and higher than ADN, as well as higher singlet energy than both Alq₃and ADN. It allows triplet diffusion from Alq₃to ADN, but blocks the SQ of the blue TTAUC signal by Alq₃. 86.1% intrinsic efficiency of TTAUC is demonstrated in this trilayer (Alq₃/DMPPP/ADN) OLED.