Lin Jiawei, Zhou Jianmin, Wang Zhihua, Li Liang, Li Maolin, Xu Jialiang, Wu Songgu, Naumov Panče, Gong Junbo
School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin, 300072, P. R. China.
Haihe Laboratory of Sustainable Chemical Transformations, Tianjin, 300192, P. R. China.
Angew Chem Int Ed Engl. 2025 Jan 21;64(4):e202416856. doi: 10.1002/anie.202416856. Epub 2024 Nov 6.
Flexible crystals with unique mechanical properties have presented potential for applications in optoelectronics, soft robotics and sensors. However, there have been no reports of low-temperature-resistant flexible crystals with second-order nonlinear optical properties (NLO). Here, we report flexible chiral Schiff-base crystals capable of efficient second harmonic generation (SHG). Both enantiomers and the racemic form of these crystals are mechanically flexible in two directions at both room temperature and at 77 K, although their mechanical responses differ. The enantiomers display SHG with an intensity of up to 12 times that of potassium dihydrogenphosphate (KDP) when pumped at 980 nm, and they also have high laser-induced damage thresholds (LDT). Even when bent, the crystals retain strong second harmonic generation, although with a different intensity distribution depending on the polarization, compared to when they are straight. This work describes the first instance of flexible organic single-crystalline material with NLO properties and lays the foundation for the development of mechanically flexible organic NLO materials.
具有独特机械性能的柔性晶体在光电子学、软体机器人和传感器领域展现出了应用潜力。然而，此前尚无关于具有二阶非线性光学特性（NLO）的耐低温柔性晶体的报道。在此，我们报告了一种能够高效产生二次谐波（SHG）的柔性手性席夫碱晶体。这些晶体的对映体和外消旋形式在室温及77 K时均在两个方向上具有机械柔性，尽管它们的机械响应有所不同。当以980 nm泵浦时，对映体的二次谐波产生强度高达磷酸二氢钾（KDP）的12倍，并且它们还具有高激光损伤阈值（LDT）。即使弯曲时，晶体仍能保持强烈的二次谐波产生，不过与伸直时相比，其强度分布会因偏振而异。这项工作描述了首例具有NLO特性的柔性有机单晶材料，并为机械柔性有机NLO材料的开发奠定了基础。
