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.