A Star of David [2]catenane of single handedness

• Published in: Chem Vol. 9; no. 4; pp. 859 - 868
• Main Authors: Feng, Hai-Na, Sun, Zhanhu, Chen, Sujun, Zhang, Zhi-Hui, Li, Zhiming, Zhong, Zhiye, Sun, Tu, Ma, Yanhang, Zhang, Liang
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 13.04.2023
• Subjects: chirality transfer; mechanically interlocked molecules; molecular links; molecular nanotopology; topological chirality; topological chirality; mechanically interlocked molecules; molecular nanotopology; molecular links; SDG9: Industry innovation and infrastructure; chirality transfer
• ISSN: 2451-9294; 2451-9294
• DOI: 10.1016/j.chempr.2022.11.010

Prime links with multiple interlocked components feature unconditional topological chirality. Although several prime links have been constructed to date, the control of their chirality with high stereoinduction is rare. Here, we report the stereoselective synthesis of an iconic molecular 612 link (Star of David [2]catenane) comprising two triply entwined 84-membered rings. The single-handed Star of David catenane is generated from the closure of a hexameric copper(I) circular helicate by ring-closing olefin metathesis, and the topological writhe (w = −6) was predetermined by the configuration of the chiral ligand. Conformation of the topology was proven through NMR spectroscopy and mass spectrometry, whereas the handedness of the link was further investigated through circular dichroism. Stereoselective synthesis of molecular nanotopologies with certain topological writhe by chiral information transfer opens the way to probe the consequences and potential of topological stereochemistry in chemistry, materials, and biology. [Display omitted] •Two-step stereoselective synthesis of a Star of David [2]catenane (612) is achieved•Topological writhe of the link is predetermined by the configuration of ligand•The catenand shows weaker CD response than that of the ligand and macrocycle A plethora of strategies have been developed for the construction of molecular links since 1960; however, the highly stereoselective synthesis of inherently chiral links is still challenging. A two-step stereoselective preparation of a topologically chiral 612 link, in the shape of a Star of David, is presented. Six equivalent of metal-ion templates is employed to drive self-assembly with six chiral building blocks into a helicate scaffold; a suitable bridge is designed between two chelating sites to direct the size of this hexamer; the length and conformational freedom of extended aliphatic olefin chains are modeled to ensure successful metathesis toward the desired connectivity; and the chiral moiety adjacent to the coordination units is placed to secure topological chirality. Such tactics are practically important in molecular nanotopology and create opportunities not only to explore the effects of chemical constitution on topological and tangled materials but also to elucidate the consequences of topological chirality in chemistry and beyond. Efficient synthesis of topologically chiral links with controlled handedness is challenging, despite several molecular prime links that have been prepared. Here, we described the two-step highly stereoselective synthesis of a Star of David [2]catenane ( 612). Use of CHIRAGENs containing chiral centers closed to coordination sites allows the transfer of the point chirality of the ligands to the topological chirality of the resulting link. This study opens the way to explore the development and potential of topological stereochemistry in chemistry and beyond.