(Self) assembled news: recent highlights from the supramolecular chemistry literature (Quarter 1, 2023)

The synthesis of pillar[n]arene macrocycles has been one of the most influential developments in the recent history of supramolecular chemistry. These macrocycles have a rich host – guest chemistry and can often be prepared in a single step. Writing in Nature Synthesis, a team led by Andrew Sue (winner of the 2021 Sessler Early Career Research Prize) have shown that pillar[5] arene derivatives can be used to form well-defined chiral nanotubes [1]. The nanotubes are formed in a singlestep condensation reaction of a penta-formyl macrocycle and phenylenediamine in quantitative yield (Figure 1). The penta-formyl compound was previously reported by the same group and was synthesised from tiara[5]arene, which was itself prepared from a rimdifferentiated pillar[5]arene [2]. Pillar[5]arenes are chiral but racemise rapidly in solution through rotation of the rings; however, in the nanotubes this rotation is locked and a pair of enantiomeric tubes were formed that could be separated using chiral HPLC. While the binding of chiral guests was not investigated, the nanotubes show strong binding of dihydroxyalkanes and dibromoalkanes with selectivity based on guest size.