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Updated: Jun 29, 2025

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
Photo-Responsive Hydrogen-Bonded Molecular Networks Capable of Retaining Crystalline Periodicity after Isomerization
Koki Kasuya1, Ryusei Oketani1, Souta Matsuda2
1Division of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, 560-8531, Toyonaka, Osaka, Japan.
Abstract:
The molecular conformation, crystalline morphology, and properties of photochromic organic crystals can be controlled through photoirradiation, making them promising candidates for functional organic materials. However, photochromic porous molecular crystals with a networked framework structure are rare due to the difficulty in maintaining space that allows for photo-induced molecular motion in the crystalline state. This study describes a photo-responsive single crystal based on hydrogen-bonded (H-bonded) network of dihydrodimethylbenzo[e]pyrene derivative 4BDHP. A crystal composed of H-bonded undulate layers, 4BDHP-2, underwent photo-isomerization in the crystalline state due to loose stacking of the layers. Particularly, enantio-pure crystal (S,S)-4BDHP-2 allowed to reveal the structure of the photoisomerized crystal, in which the closed form (4BDHP) and open form (4CPD) were arranged alternately with keeping crystalline periodicity, although side reactions were also implied. The present proof-of-concept system of a photochromic framework that retains crystalline periodicity after photo-isomerization may provide new light-driven porous functional materials.
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