π‐Stacking Enhanced Dynamic and Redox‐Switchable Self‐Assembly of Donor–Acceptor Metallo‐[2]Catenanes from Diimide Derivatives and Crown Ethers

In search of a better recipe: Bigger is better. On changing from strong donor–acceptor pairs to very weak ones, divalent 4,4′-bipyridine was no longer a suitable filler ligand to give cyclized metal–ligand coordination [2]catenanes. The choice of 2,7-diazapyrene, which has a larger π surface, proved to be essential in providing extra stabilization interactions to ensure efficient assembly (see figure).