Zhou Guojun, Yang Taimin, Huang Zhehao
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-106 91, Sweden.
Commun Chem. 2023 Jun 7;6(1):116. doi: 10.1038/s42004-023-00915-4.
Covalent organic frameworks (COFs) have been attracting intense research due to their permanent porosity, designable architecture, and high stability. However, COFs are challenging to crystallize and their synthesis often results in tiny crystal sizes and low crystallinities, which hinders an unambiguous structure determination. Herein, we demonstrate that the structure of low-crystallinity COF Py-1P nanocrystals can be solved by coupling three-dimensional electron diffraction (3DED) with simulated annealing (SA). The resulting model is comparable to that obtained from high-crystallinity samples by dual-space method. Moreover, for low-resolution 3DED data, the model obtained by SA shows a better framework than those provided by classic direct method, dual-space method, and charge flipping. We further simulate data with different resolutions to understand the reliability of SA under different crystal quality conditions. The successful determination of Py-1P structure by SA compared to other methods provides new knowledge for using 3DED to analyze low-crystallinity and nanosized materials.
共价有机框架（COFs）因其永久孔隙率、可设计的结构和高稳定性而吸引了广泛的研究。然而，COFs结晶具有挑战性，其合成通常会导致晶体尺寸微小且结晶度低，这阻碍了明确的结构测定。在此，我们证明了通过将三维电子衍射（3DED）与模拟退火（SA）相结合，可以解析低结晶度COF Py-1P纳米晶体的结构。所得模型与通过双空间方法从高结晶度样品获得的模型相当。此外，对于低分辨率的3DED数据，通过SA获得的模型比经典直接法、双空间法和电荷翻转法提供的框架更好。我们进一步模拟不同分辨率的数据，以了解在不同晶体质量条件下SA的可靠性。与其他方法相比，通过SA成功测定Py-1P结构为使用3DED分析低结晶度和纳米尺寸材料提供了新的知识。
