Synthesis of C60 /[10]CPP-Catenanes by Regioselective, Nanocapsule-Templated Bingel Bis-Addition

Abstract

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).

Keywords: Cages; Catenanes; Fullerenes; Regioselectivity; Supramolecular Dynamics.