Search for: All records

Abstract Within the field of mechanically interlocked molecules, catenanes have garnered much interest in the past few decades due to their chain‐like architecture of interlocked molecular rings. This interest stems from their unique properties and degrees of freedom that are distinct in comparison to traditional molecular architectures, a fact that makes catenanes potentially attractive building blocks in the construction of next‐generation polymeric materials. Most approaches to make unimolecular [n]catenanes are either low yielding or are laborious, often relying on multistep pathways for preparation and purification. Therefore, developing efficient syntheses for [n]catenanes remains an important challenge for chemists. Here, we describe a template‐directed one‐pot approach that overcomes the limitations of multistep syntheses by using simple, symmetrical phenanthroline‐based building blocks and CuAAC “click” chemistry to yield a series of unimolecular [n]catenanes. This methodology relies on simultaneous copper(I)‐based templation and click chemistry, ultimately resulting in a one‐pot synthetic strategy to make either a [2]catenane in high yield (82%) or a batch of well‐defined linear [2]–[5]catenanes (and trace amounts of a [6]catenane) in an 18% overall yield, depending on the rate of addition of the alkyne‐ and azide‐functionalized precursors (i.e., slowly or all at once). Such kinetic control represents a potential pathway toward the preparation of higher‐order [n]catenanes capable of further chain extension using very simple precursors. 

Catenanes are a family of mechanically interlocked molecules that consist of molecular rings that can be interlocked to give linear, radial, or cyclic structures. Although chemists have pursued extended linear poly[n]catenane architectures for many decades, there still exists a fundamental gap between the synthesis of well-defined, linear oligomers and that of disperse polymers that are often produced as a mixture of architectures. Here, we report two convergent one-pot syntheses that “zip-tie” together two pre-made [3]catenanes by first using orthogonal metal templation with phenanthroline (Cu(I)) and terpyridine (Fe(II)) ligands. These pre-catenate complexes were subjected to a ring-closing metathesis step to afford discrete, linear [7]- and [8]catenanes. The successful synthesis and isolation of the discrete [7]- and [8]catenanes were confirmed using multiple methods of characterization. Because these record-setting linear [n]catenanes possess open phenanthroline metal-binding sites at each end, further expansion to all-interlocked linear poly[n]catenanes is a realistic proposition.