Traditionally, research on interlocked molecules has focused on exploring the dynamic properties that are introduced by their mechanical bond. From a structural viewpoint, however, their densely packed architecture is also an interesting feature that offers a unique platform to examine functionalisation and supramolecular aggregation. Recently, a team led by Witold Bloch at the University of Adelaide and Guido Clever at TU Dormtund, Germany, reported the synthesis of a novel 24-component catenane that spontaenously self-assembles into large vesicle-like aggregates (Bloch W.M., Holstein J.J., Dittrich B., Hiller W., Clever G.H. Angew. Chem. Int. Ed. 2018, https://doi.org/10.1002/anie.201800490). The Pd8L16 [2]catenane is composed of two interlocking Pd4L8 barrel-shaped containers, whose assembly is facilitated by the presence of nitrate counter-ions. When functionalised with hexyloxy chains, the interlocked molecule can spontaneously self-assemble into a colloid of vesicle-like aggregates measuring 150 nm in diameter. The hierarchical aggregation is facilitated by the dense hydrophobic interactions between catenane molecules and can be completely reversed by applying a heat stimulus. This research delivers new knowledge on interlocked structures and opens up the possibility of using their hierarchical aggregates as molecular delivery and release vessels.
