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. 125 μm min−1).
How would you describe your research, compactly?Our research is, in simple words, "design of functional molecular assembles". To that end, molecular design, synthesis, and non-covalent synthesis of molecular materials are important factors.
Molecular crystals exhibiting optical waveguiding are strongly dependent on total internal reflection, molecular stacking arrangements, spatial distributions of transition dipole moments, and topologies. Fluoranthene derivatives are popular fluorescent dyes that have not yet been engineered into crystalline optical materials. Here, a naphthyl‐appended naphtho[k]fluoranthene that exhibits efficient fluorescence in solution and in the solid state is newly synthesized through a one‐pot Pd‐catalyzed reaction of 1,8‐dibromonapthalene. It selectively gives two crystal topologies derived from direction‐specific crystal growth. Using spatially resolved photoluminescence analyses, the direction‐oriented light that propagates along these topologies (each face of the crystal) is investigated. There are different optical‐loss coefficients along the various directions on each face. Therefore, face‐specific waveguiding depends on molecular arrangements. Anisotropic waveguiding in each face is observed. Overall, these results suggest potential applications of fluoranthene crystals and their topological 2D planes as optical waveguides and integrated optical circuits.
Anthracene (C 14 H 10 ) 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.
Acrylonitrile is a highly valuable unit for the design of donor–acceptor systems and luminescent π-conjugated molecular materials. Acrylonitrile-based polymers are fundamental structures in π-conjugated polymers. In contrast to the frequently...
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