Hybrid Zeolitic Imidazolate Frameworks with Catalytically Active TO4 Building Blocks

摘要

Crystalline porous materials with diverse chemical compositions (e.g., inorganic porous materials, inorganic-organic hybrid frameworks, and covalent organic frameworks) and framework topologies have been intensively studied in the past 60 years. They have wide applications in fields such as heterogeneous catalysis, gas storage, and separation. Moreover, some currently emerging areas related to health, energy use, and environmental conservation and remediation are still looking for the development of new porous materials. Zeolites are among the most well known porous materials because of their typical 4-connected open frameworks with TO4 (T = Si~(4+), Al~(3+), or P~(5+) etc.) building blocks and outstanding catalytic or gas separation properties. Recently, the search for new zeolite-like structures was extended to metal-organic frameworks (MOFs), and these explorations in part produced a variety of zeolitic imidazolate frameworks (ZIFs) in which the tetrahedrally coordinated divalent cations (M~(2+) = Zn~(2+) or Co~(2+)) are connected by the uninegative imidazolate ligands (im~-). The rich chemistry associated with the organic imidazolate building blocks in ZIFs leads to some exceptional properties, such as large surface area and high gas uptake capacities. A question that emerges is: "Are there material with properties intermediate of those of zeolites and ZIFs?". It is true that there is a hybrid state that remains unknown to date.