It is of continuing interest to design and synthesize novel macrocyclic host molecules because of their important roles in supramolecular chemistry. The successful examples include crown ethers, cyclodextrins, cucurbiturils, calixarenes, and their structurally similar scaffolds. Currently a new class of [1 n ]paracyclophanes is growing with similar composition but different structural features compared with calixarenes. This new class of macrocyclic molecules are made up of hydroquinone units linked by methylene bridges at para positions. Their descriptive name “pillararene” was coined by Tomoki Ogoshi in 2008.
