Within the field of mechanically interlocked molecules, [n]catenanes and poly[n]catenanes have garnered much interest due to their unique topology of solely interlocked macrocycles. The synthesis of higher-order unimolecular [n]catenanes with precisely controlled topology, and their integration into polymeric materials, could give chemists and material scientists a greater understanding and control over the effect of the catenane mechanical bond on the behavior of these unprecedented materials. While many variations of [n]catenane interlocked molecules have been explored in the past 60 years, the straightforward preparation of high molecular weight, linear poly[n]catenanes has only been successful a handful of times, and in many cases, the syntheses are difficult, low-yielding, and a slow process. In my presentation, I will describe more efficient and scalable synthetic protocols toward phenanthroline-based functional oligo[n]catenanes in one-pot using Cu-based passive metal templation and alternative ring-closing strategies. Our latest synthetic protocol has allowed for the isolation of distinct unimolecular, linear oligo[n]catenanes in one pot, which were easily purified away from insoluble non-catenated byproducts. The product distribution can be controlled by dilution of the one-pot reaction, or by pre-arranging metalated 1,10-phenanthroline precursors. The degree of control in this oligo[n]catenane synthetic strategy represents a crucial bridge between scalable syntheses and testing the properties of catenane-based materials. Combining this protocol with prior synthetic protocols from the Barnes research group brings the field closer to higher-scale synthesis of oligo- and poly[n]catenanes, oligo[n]catenane-based materials, and potentially even poly[n]catenane materials one day.

Figure 1. One-pot pseudo-dilute experimental setup for synthesis of oligo[<i>n</i>]catenanes.

Figure 1. One-pot pseudo-dilute experimental setup for synthesis of oligo[n]catenanes.

Nathan Colley

Appearances