Supramolecular polymers with alternating pillar[5]arene and pillar[6]arene units from a highly selective multiple host–guest complexation system and monofunctionalized pillar[6]arene

A highly selective multiple host-guest complexation system based on pillar[5]arene and pillar[6]arene is reported. A pyridinium cation moiety is included in the pillar[5]arene cavity, but hardly forms a stable host-guest complex with pillar[6]arene. A 1,4-diazabicyclo[2.2.2]octane cation moiety forms a host-guest complex with pillar[6]arene, but not with pillar[5]arene. A synthetic route to mono-reactive pillar[6]arene is also developed, enabling the synthesis of pillar[6]arene with a pyridinium cation group at a single position. Based on the highly selective multiple host-guest complexation system and mono-reactive pillar[6]arene, a supramolecular polymer with alternating pillar[5]arene and pillar[6]arene units is constructed.