Water-Soluble Cyclophanes Synthesized via the Zincke Reaction.

By taking advantage of the Zincke reaction, we successfully synthesized three macrocycles, each of which contains two bipyridinium units as the electron acceptors. Two of them contain sp2-hybridized atoms exclusively in the ring frameworks, while the third contains two methylene units. The third macrocycle is able to form 1:1 inclusion complexes with guests of complementary sizes. A pair of isomers, namely, phenanthrene and anthracene, could be separated by the third macrocycle.