Dang Li-Long, Feng Hui-Jun, Lin Yue-Jian, Jin Guo-Xin
Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, State Key Laboratory of Molecular Engineering of Polymers, Department of Chemistry, Fudan University, Shanghai 200433, P. R. China.
J Am Chem Soc. 2020 Nov 4;142(44):18946-18954. doi: 10.1021/jacs.0c09162. Epub 2020 Oct 2.
Molecular figure-eight knot (notation: 4) is extremely rare and presents great synthetic challenge due to its essentially complicated entanglement. To solve this synthetic problem, a quadruple stacking strategy was developed. Herein, we report the efficient self-assembly of figure-eight knots induced by quadruple stacking interactions, through the combination of four carefully selected naphthalenediimide (NDI)-based pyridyl ligands and CpRh building blocks bearing large conjugated planes in a single-step strategy. Notably, slight size adjustment of the CpRh units was found to affect the stability of the figure-eight knots in methanol. Additionally, reversible structural transformations between these figure-eight knots and corresponding metallorectangles could be achieved by concentration changes and solvent- and guest-induced effects. X-ray crystallographic data and NMR spectroscopy provide full confirmation of these phenomena.
分子8字结（符号：4）极其罕见，因其本质上复杂的缠结而带来巨大的合成挑战。为了解决这一合成问题，开发了一种四重堆积策略。在此，我们报告了通过四重堆积相互作用诱导的8字结的高效自组装，该过程通过在一步策略中结合四个精心选择的基于萘二酰亚胺（NDI）的吡啶基配体和带有大共轭平面的CpRh结构单元来实现。值得注意的是，发现对CpRh单元进行轻微的尺寸调整会影响8字结在甲醇中的稳定性。此外，通过浓度变化以及溶剂和客体诱导效应，可以实现这些8字结与相应金属矩形之间的可逆结构转变。X射线晶体学数据和核磁共振光谱充分证实了这些现象。
