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 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 catenanes were studied in silico with atomistic resolution. This work significantly widens the scope of mechanically interlocked architectures comprising cycloparaphenylenes (CPP).

This work involved Prof. Giovanni M. Pavan of the University of Applied Sciences and Arts of Southern Switzerland, Prof. Max von Delius of the Ulm University and Ernest Ubasart, Míriam Pujals, Prof. Xavi Ribas of the QBIS-CAT group of the Institute of Computational Chemistry and Catalysis (IQCC) of the University of Girona.

It has recently been published in the Angewandte Chemie International Edition:

F. M. Steudel, E. Ubasart, L. Leanza, M. Pujals, T. Parella, G. M. Pavan*, X. Ribas*, M. von Delius*
“Synthesis of C60/CPP-Catenanes by Regioselective, Nanocapsule-Templated Bingel Bis-Addition”
Angew. Chem. Int. Ed., 2023, ASAP
DOI: 10.1002/anie.202309393

Girona, September 22, 2023
For more info: ges.iqcc@udg.edu