Superflexible Fluorescent π-Conjugated Organic Crystals: Synergistic Mechanical-Optical Properties and Molecular Engineering Insights

作者：Chunyan Zhang, Jiayao Li, Feiqiang He, Zhi Gao, Yijing Xiang, Limin Zhou, Xu LI, Jerry Y. Y. Heng, Yifu Chen, Shichao Du, Jinbo Ouyang · 发表于：Crystal Growth & Design · 年份：2025 · DOI：10.1021/acs.cgd.5c01167 · 被引用次数：4 · 研究领域：Luminescence and Fluorescent Materials、Crystallography and molecular interactions、Nonlinear Optical Materials Studies

Molecular crystals exhibit broad application prospects in the field of flexible functional materials due to their unique elastic behavior. This study designed and synthesized four structurally similar flexible molecular crystals with fluorescence properties. Among them, three crystals contain −C═N–NH– groups (named Bhn, Chn, Pthn), while the fourth incorporates −N═N– group (termed Modn). The mechanical response characteristics of these crystals were systematically explored through a comprehensive series of analyses. Experimental results demonstrate that, under external force stimulation, the four crystals exhibit differentiated bending performance, among which Pthn and Modn crystals can achieve complete 180° bending, showcasing excellent flexibility. Through three-point bending tests and nanoindentation techniques, the mechanical properties of these two large-sized single crystals were quantitatively characterized. It was found that they can withstand ultralarge strains of 80% and 120% respectively under extremely low stress conditions before fracturing, while also possessing low elastic moduli ( E Pthn = 3.17 ± 0.11 GPa, E Modn = 3.75 ± 0.13 GPa) and hardness values ( H Pthn = 0.13 ± 0.02 GPa, H Modn = 0.23 ± 0.01 GPa), confirming their outstanding mechanical flexibility and ductility. Furthermore, under ultraviolet excitation, all four crystals emit orange-red fluorescence (λ > 600 nm), but with significant differences in fluorescence intensity. This synergistic regulation ...