Convenient Multigram-Scale Synthesis of Phase-Pure Zirconium Metal-Organic Cages

Cationic zirconocene-based metal-organic cages (ZrMOCs) recently found significant research interest for applications in porous salts. However, their widespread use remained hindered by the coexistence of two types of cages, tetrahedral and cigar-shaped, in most syntheses and by low synthesis throughput. Here, we describe the multigram-scale synthesis of several types of ZrMOCs, achieving purity higher than 99% for either tetrahedra or cigars by combining a systematic analysis of reaction conditions and the development of an efficient purification procedure based on the difference in solubility. The access to phase-pure reference compounds also allowed us to analyze the effect of cage coexistence on the physical properties and pore accessibility in mixtures.