Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, School of Chemistry and Molecular Engineering , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , China.
Department of Chemical Engineering , University of Virginia , 102 Engineers' Way , P.O. Box 400741, Charlottesville , Virginia 22904 , United States.
J Am Chem Soc. 2019 Aug 14;141(32):12804-12814. doi: 10.1021/jacs.9b05740. Epub 2019 Aug 2.
Programming the hierarchical self-assembly of small molecules has been a fundamental topic of great significance in biological systems and artificial supramolecular systems. Precise and highly programmed self-assembly can produce supramolecular architectures with distinct structural features. However, it still remains a challenge how to precisely control the self-assembly pathway in a desirable way by introducing abundant structural information into a limited molecular backbone. Here we disclose a strategy that directs the hierarchical self-assembly of sodium thioctate, a small molecule of biological origin, into a highly ordered supramolecular layered network. By combining the unique dynamic covalent ring-opening-polymerization of sodium thioctate and an evaporation-induced interfacial confinement effect, we precisely direct the dynamic supramolecular self-assembly of this simple small molecule in a scheduled hierarchical pathway, resulting in a layered structure with long-range order at both macroscopic and molecular scales, which is revealed by small-angle and wide-angle X-ray scattering technologies. The resulting supramolecular layers are found to be able to bind water molecules as structural water, which works as an interlayer lubricant to modulate the material properties, such as mechanical performance, self-healing capability, and actuating function. Analogous to many reversibly self-assembled biological systems, the highly dynamic polymeric network can be degraded into monomers and reformed by a water-mediated route, exhibiting full recyclability in a facile, mild, and environmentally friendly way. This approach for assembling commercial small molecules into structurally complex materials paves the way for low-cost functional supramolecular materials based on synthetically simple procedures.
小分子的层级自组装编程一直是生物系统和人工超分子系统中一个具有重要意义的基础课题。精确和高度编程的自组装可以产生具有独特结构特征的超分子结构。然而，如何通过在有限的分子主链中引入丰富的结构信息来精确控制所需的自组装途径，仍然是一个挑战。在这里，我们揭示了一种策略，该策略可以指导生物起源的小分子硫辛酸的层级自组装成高度有序的超分子层状网络。通过结合硫辛酸独特的动态开环聚合和蒸发诱导的界面限制效应，我们精确地引导这个简单小分子的动态超分子自组装沿着预定的层级途径进行，从而在宏观和分子尺度上都产生具有长程有序的层状结构，这一点通过小角和广角 X 射线散射技术得到了揭示。结果表明，所得的超分子层能够结合水分子作为结构水，作为层间润滑剂来调节材料性能，如机械性能、自修复能力和驱动功能。类似于许多可还原自组装的生物系统，高度动态的聚合物网络可以通过水介导的途径降解为单体并重新形成，以简单、温和和环保的方式实现完全可回收性。这种将商业小分子组装成结构复杂材料的方法为基于合成简单程序的低成本功能超分子材料铺平了道路。
