Unlocking Advanced Architectures of Single-Crystal Metal-Organic Frameworks

Abstract

The synthesis of metal-organic frameworks (MOFs) with diverse geometries has captivated considerable interest due to their manifestation of novel and extraordinary properties. While much progress has been made in shaping regular polyhedral single-crystal MOFs, the creation of more complex, topologically intricate nanostructures remains a largely unexplored frontier. Here, we present a refined site-specific anisotropic assembly and etching co-mediation approach to fabricate a series of hierarchical MOF nanohybrids and single-crystal MOFs. This approach yields ZIF-8&mSiO2 nanohybrids with diverse topologies, alongside derived single-crystal MOF nanoparticles exhibiting intricate morphologies such as hexapods, nested nanocages, and octopods. Our method involves the selective growth of six mSiO2 nanoplates on the {100} facets of ZIF-8 nanocubes, forming the cubic-shaped ZIF-8&mSiO2 nanohybrids, with the concurrent etching of the {110} facets of initial ZIF-8 nanocubes. By fine-tuning this balance between the growth and etching, we achieved precise morphological control, transforming cubic nanohybrids into intricate hexapods nanohybrids. Additionally, secondary epitaxial growth of homo- or hetero-MOFs on these hybrids led to ZIF-8&mSiO2&MOF composites with six mSiO2 inlays. Finally, selective alkaline etching of the mSiO2 compartments result in single-crystal MOF nanoparticles with unprecedented and sophisticated morphologies, such as hexapods, nested nanocages, octopods.