Framework crystallization is an unresolved challenge in the chemistry of covalent organic frameworks (COFs) due to the poorly controlled simultaneous polymerization and crystallization processes. Here, we report the first morphogenesis of COF mesocrystals with two-dimensional hexagonal p6m symmetry through the combination of alkyl amine as a dynamic modulator and 2,4,6- triformylresorcinol imine as an asymmetrical building block. The amine modulator depresses the lateral growth of 2D sheets, and the slow kinetics combined with the asymmetrical conformation of 2,4,6-triformylresorcinol imine lead to the formation of transient imine macrocycles, which further undergo mesoscale self-assembly into nanotubular structures. The nanotubular structures tend to join together into rod-like bundles with ordered hexagonal rods, which finally grow into uniform hexagonal COF mesocrystals. The present strategy opens a nonclassical nucleation and crystal growth approach to create COFs with unexplored mesocrystal structures, which further extends the scope of crystalline framework materials and provides a new strategy for crystal morphogenesis.

中文翻译：

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通过动态调节剂操作的亚胺大环前体的中尺度自组装共价有机框架介晶。

骨架结晶是共价有机骨架（COF）化学中一个尚未解决的挑战，因为同时聚合和结晶过程控制不佳。在这里，我们通过烷基胺作为动态调节剂和2,4,6-三甲酰间苯二酚亚胺作为不对称结构单元的组合，报告了具有二维六边形p6m对称性的COF介晶的首次形态发生。胺调节剂抑制2D片材的横向生长，缓慢的动力学与2,4,6-三甲酰间苯二酚亚胺的不对称构象相结合导致形成瞬态亚胺大环，后者进一步经历中尺度自组装成纳米管结构。纳米管结构倾向于通过有序的六边形棒连接成棒状束，最终长成均匀的六角形COF介晶。本策略打开了一种非经典的成核和晶体生长方法，以创建具有未经探索的中晶结构的COF，这进一步扩展了晶体框架材料的范围，并为晶体形态发生提供了新的策略。