Hayashi Shotaro, Ishiwari Fumitaka, Fukushima Takanori, Mikage Shohei, Imamura Yutaka, Tashiro Motomichi, Katouda Michio
Research Center for Molecular Design, School of Environmental Science and Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami, Kochi, 782-8502, Japan.
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Angew Chem Int Ed Engl. 2020 Sep 7;59(37):16195-16201. doi: 10.1002/anie.202006474. Epub 2020 Jul 14.
Elastic organic crystals have attracted considerable attention as next-generation flexible smart materials. However, the detailed information on both molecular packing change and macroscopic mechanical crystal deformations upon applied stress is still insufficient. Herein, we report that fluorescent single crystals of 9,10-dibromoanthracene are elastically bendable and stretchable, which allows a detailed investigation of the deformation behavior. We clearly observed a Poisson effect for the crystal, where the short axes (b and c-axes) of the crystal are contracted upon elongation along the long axis (a-axis). Moreover, we found that the Poisson's ratios along the b-axis and c-axis are largely different. Theoretical molecular simulation suggests that the tilting motion of the anthracene may be responsible for the large deformation along the c-axis. Spatially resolved photoluminescence (PL) measurement of the bent elastic crystals reveals that the PL spectra at the outer (elongated), central (neutral), and inner (contracted) sides are different from each other.
弹性有机晶体作为下一代柔性智能材料已引起了相当大的关注。然而，关于施加应力时分子堆积变化和宏观机械晶体变形的详细信息仍然不足。在此，我们报道9,10-二溴蒽荧光单晶具有弹性可弯曲和可拉伸性，这使得对其变形行为进行详细研究成为可能。我们清楚地观察到该晶体存在泊松效应，即晶体的短轴（b轴和c轴）在沿长轴（a轴）伸长时会收缩。此外，我们发现沿b轴和c轴的泊松比有很大差异。理论分子模拟表明，蒽的倾斜运动可能是导致沿c轴发生大变形的原因。对弯曲弹性晶体进行空间分辨光致发光（PL）测量发现，晶体外侧（伸长）、中心（中性）和内侧（收缩）的PL光谱彼此不同。
