Endohedral dynamics of push–pull rotor-functionalized cages

Abstract

A series of [Pd₂L₄] coordination cages featuring endohedral functionalities in central backbone positions was synthesized. Although attached via CC double bonds, the substituents behave as molecular rotors. This is explained by their pronounced donor–acceptor character which lowers rotational barriers and allows for electronic control over the spinning rates inside the cage. The dynamic behaviour of the free ligands, assembled cages and host–guest complexes is compared with the aid of NMR experiments, X-ray structure analysis and molecular modelling.