RESUMEN
Invited for this month's cover is the collaborating group of Prof. Shotaro Hayashi at Kochi University of Technology. The cover picture shows anthracene molecules depicted among sakura blossoms at Kochi University of Technology (KUT). Anthracenes are arranged with falling petals, giving a beautiful image of the molecular crystal engineering field. The cover was designed by Yuto Hino. More information can be found in the Review by S. Hayashi and co-workers.
RESUMEN
Anthracene (C14 H10 ) and its derivatives, π-conjugated molecules in acenes, have been widely researched in terms of their reactions, physical properties, and self-assembly (or crystal engineering). These molecules can be functionalized to tune reactivities, optoelectronic properties, and self-assembling abilities. Structural changes in the molecular assemblies, solid states, and crystals have recently been discovered. Therefore, a systematic discussion of anthracene's molecular structure, packing, and optical properties based on its intermolecular structure and phase transitions is important for future chemical and structural design. In the present review, we discuss anthracene's molecular design, dimer packing, and crystal structure, focusing on the structural phase transitions of its crystals. We also provide examples of the phase transitions of anthracene crystals. Changes to edge-to-face of CH-π interaction and face-to-face packing of π-π interaction affect the thermodynamic stabilities of various crystal structures. These structures can inform the prediction of structural and physical properties.
RESUMEN
Stimuli-triggered crystal-to-crystal and single-crystal-to-single-crystal (SCSC) transformations have received significant attention in the scientific community. To visualize such phenomenon, controlling the optical properties and the thermodynamic stability of the molecular crystals is a very important research subject. In this report, the selective growth of photoluminescent (PL) 1,8-bisphenylanthracene polymorphic (cI and cII) and 1,2-dichloroethane-inclusion crystals (iC) under various optimized conditions is described. These crystals exhibited unique mechano- and thermoresponsive disordering, crystal-to-crystal phase transition, and SCSC phase transition. In particular, rapid thermostimulus SCSC occurred from blue-PL cI into greenish-blue-PL cII. Interestingly, the SCSC phase transition of cI into cII was triggered by thermal stimuli and propagated spontaneously. Thermotriggered domino-like SCSC phase transition was observed on a fully visible timescale (ca. 125â µm min-1 ).