Hierarchical Self‐Assembly of Capsule‐Shaped Zirconium Coordination Cages with Quaternary Structure

Abstract

Abstract Biological macromolecules exhibit emergent functions through hierarchical self‐assembly, a concept that is extended to design artificial supramolecular assemblies. Here, the first example of breaking the common parallel arrangement of capsule‐shaped zirconium coordination cages is reported by constructing the hierarchical porous framework ZrR‐1. ZrR‐1 adopts a quaternary structure resembling protein and contains 12‐connected chloride clusters, representing the highest connectivity for zirconium‐based cages reported thus far. Compared to the parallel framework ZrR‐2, ZrR‐1 demonstrated enhanced stability in acidic aqueous solutions and a tenfold increase in BET surface area (879 m2 g−1). ZrR‐1 also exhibits excellent proton conductivity, reaching 1.31 × 10−2 S·cm−1 at 353 K and 98% relative humidity, with a low activation energy of 0.143 eV. This finding provides insights into controlling the hierarchical self‐assembly of metal–organic cages to discover superstructures with emergent properties.

Keywords

• hierarchical self‐assembly
• hydrogen bonding
• proton conductivity
• quaternary structure
• zirconium coordination cages