Solid-State Self-Assembly of Heteroditopic Copillar[5]arenes

Abstract

Self-assembly is a fundamental bottom-up tool for the construction of living or synthetic materials. Owing to the specific, definite, and directional host–guest interactions, heteroditopic monomers has become one of the classic models as building blocks in self-assembly investigation. Driven by the unique multiple CH···π interactions between the pillar[5]arene cavity and the linear n-alkyl group, copillar[5]arenes have become one of the simplest and optimal models for the construction of heteroditopic monomers in recent years. Here, by comparison of the reported crystal structures of heteroditopic copillar[5]arenes with six new ones (P6Br, P8Br, P6Im, P10Im, P4 ⊃ acetonnitrile, and P8Br ⊃ succinonitrile), we found that their self-assembly manner in the solid state was primarily decided by the competition of the pillar[5]arene cavity between the threading guest moiety and the solvent molecules (or external competitors). When the competitor had much higher affinity to the pillar[5]arene cavity, a traditional host–guest complex would be formed in the solid state. When the threading guest moiety showed much higher affinity, [cn]daisy chains (normally [c2]) would be formed. It was further found that only when they had similar bonding abilities with the pillar[5]arene cavity, [an]daisy chains could be formed in the solid state.