Synthesis of C-60/[10]CPP-Catenanes by Regioselective, Nanocapsule-Templated Bingel Bis-Addition

The addition of two unsymmetric malonate esters to the Buckminster fullerene C60 can lead to 22 spectroscopically distinguishable isomeric products and therefore represents a formidable synthesis challenge. In this work, we achieve 87 % selectivity for the formation of a single (in,out-trans-3) isomer by combining three approaches: (i) we use a starting material, in which the two malonates are covalently connected (tether approach); (ii) we form the strong supramolecular complex of C60 with the shape-persistent [10]CPP macrocycle (template approach) and (iii) we embed this complex further within a self-assembled nanocapsule (shadow mask approach). Variation of the spacer chain shed light on the limitations of the approach and the ring dynamics in the unusual [2]catenanes were studied in silico with atomistic resolution. This work significantly widens the scope of mechanically interlocked architectures comprising cycloparaphenylenes (CPP).

Automated summary

This study demonstrates the successful synthesis of a challenging task by adding two unsymmetric malonate esters to Buckminster fullerene C60, resulting in 22 spectroscopically distinguishable isomeric products. By combining three different approaches, namely tether approach, template approach, and shadow mask approach, the researchers achieved 87% selectivity for the formation of a single isomer.