Xia Guomin, Zhou Chunlei, Xiao Xingliang, Yang Yang, Yu Fuqing, Wang Hongming
Jiangxi Provincial Key Laboratory of Functional Crystalline Materials Chemistry Nanchang 330031 China
Institute for Advanced Study, Nanchang University Nanchang 330031 China.
Chem Sci. 2024 Aug 6;15(35):14336-43. doi: 10.1039/d4sc02751e.
The polymorphic self-correction from a metastable phase to a stable one often occurs and plays crucial roles in synthesizing robust hydrogen-bonded organic frameworks (HOFs). However, identifying metastable phases and understanding the self-correcting mechanisms is a challenging venture due to their intrinsic instability. Here, we for the first time introduce 1,8-naphtholactam (Np) as a hydrogen-bonding synthon positioned on the periphery of a bicarbazole to create a versatile molecular unit for 3D HOFs. The as-synthesized NCU-HOF1, analyzed by single-crystal X-ray diffraction (SCXRD), is found to be metastable. It exhibits an 11-fold interpenetrated dia topology with a quarter of the Np units exhibiting monomeric N-H⋯O interactions between adjacent Np link sites, which readily self-correct upon desolvation to form fully dimeric ones. Consequently, the resultant NCU-HOF1a becomes highly robust in polar solvents, strong acid or alkaline aqueous solutions, and has permanent porosity with contracted cavities for selective adsorption and efficient "turn-up" fluorescent sensing of CH gas. This work not only debuts a new hydrogen-bonding synthon but offers more insights into investigating solid-state dynamics in metastable HOFs.
从亚稳相到稳定相的多晶型自校正经常发生，并且在合成坚固的氢键有机框架（HOF）中起着关键作用。然而，由于其固有的不稳定性，识别亚稳相和理解自校正机制是一项具有挑战性的工作。在这里，我们首次引入1,8-萘内酰胺（Np）作为位于双咔唑外围的氢键合成子，以创建用于三维HOF的通用分子单元。通过单晶X射线衍射（SCXRD）分析，合成的NCU-HOF1被发现是亚稳的。它呈现出11重互穿的dia拓扑结构，四分之一的Np单元在相邻的Np连接位点之间表现出单体N-H⋯O相互作用，在去溶剂化时很容易自校正形成完全二聚体。因此，所得的NCU-HOF1a在极性溶剂、强酸或碱性水溶液中变得高度坚固，并且具有收缩腔的永久孔隙率，用于选择性吸附和对CH气体的高效“开启”荧光传感。这项工作不仅首次展示了一种新的氢键合成子，而且为研究亚稳HOF中的固态动力学提供了更多见解。
