TY - JOUR
T1 - Polymorph-Derived Diversification of Crystal Actuation by Photoisomerization and the Photothermal Effect
AU - Hasebe, Shodai
AU - Hagiwara, Yuki
AU - Takechi, Kyoko
AU - Katayama, Tetsuro
AU - Furube, Akihiro
AU - Asahi, Toru
AU - Koshima, Hideko
N1 - Funding Information:
This research was supported by JSPS Grant-in-Aid for Scientific Research B (17H03107). We thank Photron Ltd. for lending the high-speed camera. Y.H. appreciates JSPS’s Research Fellowship for Young Scientists. S.H. and Y.H. thank the Graduate Program for Power Energy Professionals, Waseda University from MEXT WISE Program.
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/2/8
Y1 - 2022/2/8
N2 - Mechanically responsive materials have been investigated extensively over the past two decades. Diversification of actuation modes is essential for the practical application of mechanical materials. Polymorphic crystals with different crystal structures composed of the same compound can exhibit distinct mechanical motions. Here, we focused on two polymorphs of a salicylideneaniline derivative with a 4-fluoro substituent in enol form, 1α and 1β, and investigated their different photomechanical behaviors. Under ultraviolet (UV) light irradiation, the thin plate-like 1α crystal bent away gradually and strongly from the light source, with some twist caused by enol-keto photoisomerization. In contrast, the thin, needle-like 1β crystal did not bend by photoisomerization; however, the thick 1β crystal bent away quickly from the light source because of the photothermal effect, ultimately achieving 500 Hz high-speed bending under pulsed UV laser irradiation. Moreover, the thick plate-like 1α crystal exhibited two-step motion: fast bending forward by the photothermal effect and then slow bending away by photoisomerization. We succeeded in creating four motions using two polymorphic crystals and two distinct mechanisms, thereby providing a novel approach to diversify the mechanical motions of molecular crystals and expanding the potential and versatility of molecular crystals as actuation materials.
AB - Mechanically responsive materials have been investigated extensively over the past two decades. Diversification of actuation modes is essential for the practical application of mechanical materials. Polymorphic crystals with different crystal structures composed of the same compound can exhibit distinct mechanical motions. Here, we focused on two polymorphs of a salicylideneaniline derivative with a 4-fluoro substituent in enol form, 1α and 1β, and investigated their different photomechanical behaviors. Under ultraviolet (UV) light irradiation, the thin plate-like 1α crystal bent away gradually and strongly from the light source, with some twist caused by enol-keto photoisomerization. In contrast, the thin, needle-like 1β crystal did not bend by photoisomerization; however, the thick 1β crystal bent away quickly from the light source because of the photothermal effect, ultimately achieving 500 Hz high-speed bending under pulsed UV laser irradiation. Moreover, the thick plate-like 1α crystal exhibited two-step motion: fast bending forward by the photothermal effect and then slow bending away by photoisomerization. We succeeded in creating four motions using two polymorphic crystals and two distinct mechanisms, thereby providing a novel approach to diversify the mechanical motions of molecular crystals and expanding the potential and versatility of molecular crystals as actuation materials.
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U2 - 10.1021/acs.chemmater.1c04007
DO - 10.1021/acs.chemmater.1c04007
M3 - Article
AN - SCOPUS:85123589987
SN - 0897-4756
VL - 34
SP - 1315
EP - 1324
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 3
ER -