[2]Pseudorotaxanes and [2]Catenanes Constructed by Oxacalixcrowns/Viologen Molecular Recognition Motifs

Oxacalix­[2]­arene­[2]­pyrazine and functional polyether derived oxacalixcrown-6, -7, and -8 were synthesized, and their host–guest complexation with paraquat to form [2]­pseudorotaxanes was studied. The [2]­pseudorotaxanes were then successfully used in the construction of two oxacalixcrown-tetracationic cyclophane [CBPQT⁴⁺] based [2]­catenanes.