College of Chemistry and Chemical Engineering, Luoyang Normal University, Henan Province Function-Oriented Porous Materials Key Laboratory, Luoyang, 471934, P. R. China.
State Key Laboratory of Molecular Engineering of Polymers, Department of Chemistry, Fudan University, Shanghai, 200433, P. R. China.
Angew Chem Int Ed Engl. 2023 May 8;62(20):e202301516. doi: 10.1002/anie.202301516. Epub 2023 Apr 13.
Intricately interwoven topologies are continually being synthesized and are ultimately equally versatile and significant at the nanoscale level; however, reports concerning ravel structures, which are highly entwined new topological species, are extremely rare and fraught with tremendous synthesis challenges. To solve the synthesis problem, a tetrapodontic pyridine ligand L1 with two types of olefinic bond units and two Cp*M-based building blocks (E1, M=Rh; E2, M=Ir) featuring large conjugated planes was prepared to perform the self-assembly. Two unprecedented [5+10] icosanuclear molecular 4-ravels containing four crossings were obtained by parallel-displaced π⋅⋅⋅π interactions in a single-step strategy. Remarkably, reversible structural transformations between the 4-ravel and the corresponding metallocage could be realized by concentration changes and solvent- and guest-induced effects. X-ray crystallographic data and NMR spectroscopy provide full confirmation of these phenomena.
错综复杂的拓扑结构不断被合成，最终在纳米尺度上同样具有多功能性和重要性；然而，有关缠结结构的报道极为罕见，这些结构是高度缠结的新拓扑物种，而且合成极具挑战性。为了解决这个合成问题，我们制备了一种具有两种类型烯烃键单元和两个基于 Cp*M 的构筑块（E1，M=Rh；E2，M=Ir）的四齿吡啶配体 L1，其具有较大的共轭平面，用于进行自组装。通过平行错位的π⋅⋅⋅π相互作用，在单一步骤策略中得到了两个前所未有的[5+10]icosanuclear 分子 4-ravel，其中包含四个交叉点。值得注意的是，通过浓度变化和溶剂及客体诱导效应，可以实现 4-ravel 和相应的金属笼之间的可逆结构转变。X 射线晶体学数据和 NMR 光谱学提供了对这些现象的充分证实。
