Mahapatra Sayantan, Qian Dingwen, Zhang Ruihua, Yang Shuliang, Li Penghao, Feng Yuanning, Zhang Long, Wu Huang, Seale James S W, Das Partha Jyoti, Jha Prateek K, Kohlstedt Kevin Lee, Olvera de la Cruz Monica, Stoddart J Fraser
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
Applied Physics Graduate Program, Northwestern University, Evanston, Illinois 60208, United States.
J Am Chem Soc. 2024 Aug 7;146(31):21689-21699. doi: 10.1021/jacs.4c05804. Epub 2024 Jul 29.
In reticular chemistry, molecular building blocks are designed to create crystalline open frameworks. A key principle of reticular chemistry is that the most symmetrical networks are the likely outcomes of reactions, particularly when highly symmetrical building blocks are involved. The strategy of synthesizing low-dimensional networks aims to reduce explicitly the symmetry of the molecular building blocks. Here we report the spontaneous formation of hydrogen-bonded fibrous structures from trigonal prismatic building blocks, which were designed to form three-dimensional crystalline networks on account of their highly symmetrical structures. Utilizing different microscopic and spectroscopic techniques, we identify the structures at the early stages of the assembly process in order to and understand the growth mechanism. The symmetrical molecular building blocks are incorporated preferentially in the longitudinal direction, giving rise to anisotropic hydrogen-bonded porous organic nanotubes. Entropy-driven anisotropic growth provides micrometer-scale unidirectional nanotubes with high porosity. By combining experimental evidence and theoretical modeling, we have obtained a deep understanding of the nucleation and growth processes. Our findings offer fundamental insight into the molecular design of tubular structures. The nanotubes evolve further in the transverse directions to provide extended higher-order fibrous structures [nano- and microfibers], ultimately leading to large-scale interconnected hydrogen-bonded fiber-like structures with twists and turns. Our work provides fundamental understanding and paves the way for innovative molecular designs in low-dimensional networks.
在网状化学中，分子构建块被设计用于创建晶体开放框架。网状化学的一个关键原则是，最对称的网络是反应的可能产物，特别是当涉及高度对称的构建块时。合成低维网络的策略旨在明确降低分子构建块的对称性。在此，我们报告了由三角棱柱形构建块自发形成氢键纤维结构，这些构建块因其高度对称的结构而被设计用于形成三维晶体网络。利用不同的显微镜和光谱技术，我们确定了组装过程早期阶段的结构，以便理解生长机制。对称的分子构建块优先在纵向方向上结合，形成各向异性的氢键多孔有机纳米管。熵驱动的各向异性生长提供了具有高孔隙率的微米级单向纳米管。通过结合实验证据和理论建模，我们对成核和生长过程有了深入理解。我们的发现为管状结构的分子设计提供了基本见解。纳米管在横向方向上进一步演化，形成延伸的高阶纤维结构[纳米纤维和微纤维]，最终导致大规模相互连接的具有曲折的氢键纤维状结构。我们的工作提供了基本理解，并为低维网络中的创新分子设计铺平了道路。
