Self-assembly and dynamic exchange of cuboctahedral metal–organic cages†

Abstract

Due to their unique physical and chemical properties, metal–organic cage structures have great potential for applications in various fields. However, current studies have mainly focused on highly symmetric structures assembled from single metal ions and organic ligands, limiting their diversity and complexity, and there are still relatively few studies on the dynamic formation process of metal–organic cages. Herein, we constructed a series of metal–organic cages with different sizes assembled from the highly-stable coordination of 2,2′:6′,2′′-terpyridine-based tetratopic ligands and various metals ions such as Zn, Cu, Co and Fe. Furthermore, the intermolecular exchange process between the metal–organic cages was explored through the dynamic exchange of ligands, and the formation of a series of hybrid supramolecular nanocages together with their final tendency to form a predominant structure of M₂₄L1₄L2₈ was observed. In addition, the binding of metal–organic cages with 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl) porphyrin-Zn was also investigated. This study not only expands the complexity and diversity of metal–organic cages, but also provides a new perspective for studying the dynamic behaviour of metal–organic cages.