Macrocyclic chemistry has been around for several decades, and has driven the now much wider fields of supramolecular chemistry. A novel entity in this field was constructed by Ogoshi and co-workers, who constructed in a simple manner so-called pillar-arenes (JACS 2008, 5022), named after its molecular shape (in short: P5, for the five-membered rings). Its easy, high-yielding synthesis and rapidly growing range of applications, e.g. in the separation of isomers with near-identical boiling points, yielded a lot of attention. A basic structural question then popped up, namely: can one synthesize such molecules with a different top and bottom structure, so-called: rim-differentiated pillararenes. This was accomplished in 2018 (JACS 2018, 74), and additional studies showed both increased synthetic flexibility of our approach (OrgLett 2019, 3976) and even the possibility to turn all functionalities on one rim into C-H moieties (Angew Chem 2020, 3994).
Current investigations focus on fundamental properties of such and related macrocycles (structure, formation, dynamics, relation between solid-state structure and solution structure), and on applications thereof in the field of surface-bound chemistry.