A General Synthesis of Macrocyclic π-Electron-Acceptor Systems

Cyclocondensations of aromatic diamines with 1,1′-bis(2,4-dinitrophenyl)-4,4′-bipyridinium salts afford doubly or quadruply charged, macrocyclic, N,N′-diarylbipyridinium cations. These are tolerant of a wide range of acids, bases, and nucleophiles, although they appear to undergo reversible, one-electron reduction by tertiary amines. Single-crystal X-ray analysis demonstrates the presence of a macrocycle conformation in which the 4,4′-bipyridinium and 4,4′-biphenylenedisulfonyl residues are suitably spaced and aligned for complexation with π-donor arenes, and NMR studies in solution indeed confirm binding to 1,5-bis[hydroxy(ethoxy)ethoxy]naphthalene.