Effects of Metal Cations and Counter Anions on the Structural Stability of Isoquinoline-Based Metallo-Supramolecular Cages

Metallo-supramolecular architectures that are constructed by coordination-driven self-assembly have received tremendous attention on account of their diverse yet molecular-level precise structures and broad applications. Of particular, metal cations and counter anions are fundamentally important in terms of self-assembly, characterization and property; however, their effects on the structural stabilities of metallo-supramolecular architectures have seldom been investigated. To address this issue, herein, a series of octahedral metallo-cages that are capable of tolerating with five metal cations (Pd2+, Cu2+, Ni2+, Co2+ and Zn2+), and five counter anions (ClO4-, OTf-, BF4-, NTf2- and NO3-) are constructed by the coordination-driven self-assembly of a well-designed tritopic isoquinoline-based ligand with corresponding metal salts. Structural stability studies show that metal cations and counter anions play a critical role in the stability of the resulting cages depending on their coordination abilities and stacking manners. This work provides deep insights in the ever-diversifying field of metallo-supramolecular chemistry, and will enable us to design more sophisticated assembled structure with desired function.