Kang Chengjun, Yang Kuiwei, Zhang Zhaoqiang, Usadi Adam K, Calabro David C, Baugh Lisa Saunders, Wang Yuxiang, Jiang Jianwen, Zou Xiaodong, Huang Zhehao, Zhao Dan
Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585, Singapore.
ExxonMobil Asia Pacific Pte. Ltd., 1 HarbourFront Place HarbourFront Tower 1, Singapore, 098633, Singapore.
Nat Commun. 2022 Mar 16;13(1):1370. doi: 10.1038/s41467-022-29086-x.
Resolving single-crystal structures of two-dimensional covalent organic frameworks (2D COFs) is a great challenge, hindered in part by limited strategies for growing high-quality crystals. A better understanding of the growth mechanism facilitates development of methods to grow high-quality 2D COF single crystals. Here, we take a different perspective to explore the 2D COF growth process by tracing growth intermediates. We discover two different growth mechanisms, nucleation and self-healing, in which self-assembly and pre-arrangement of monomers and oligomers are important factors for obtaining highly crystalline 2D COFs. These findings enable us to grow micron-sized 2D single crystalline COF Py-1P. The crystal structure of Py-1P is successfully characterized by three-dimensional electron diffraction (3DED), which confirms that Py-1P does, in part, adopt the widely predicted AA stacking structure. In addition, we find the majority of Py-1P crystals (>90%) have a previously unknown structure, containing 6 stacking layers within one unit cell.
解析二维共价有机框架（2D COFs）的单晶结构是一项巨大挑战，部分原因是高质量晶体生长策略有限。更好地理解生长机制有助于开发高质量2D COF单晶的生长方法。在此，我们从不同角度通过追踪生长中间体来探索2D COF的生长过程。我们发现了两种不同的生长机制，即成核和自愈，其中单体和低聚物的自组装和预排列是获得高结晶度2D COFs的重要因素。这些发现使我们能够生长出微米级的2D单晶COF Py-1P。通过三维电子衍射（3DED）成功表征了Py-1P的晶体结构，这证实Py-1P部分采用了广泛预测的AA堆积结构。此外，我们发现大多数Py-1P晶体（>90%）具有以前未知的结构，在一个晶胞内包含6个堆积层。
