Encapsulation of 4,4′-bipyridinium cations by two crown ether molecules: formation and structure of [3]pseudorotaxanes†
Abstract
Substituted 4,4′-bipyridinium cations (viologens) typically form 1 : 1 complexes with crown ethers. In this paper the formation of trimolecular [3]pseudorotaxanes whereby each viologen coordinates two