Multivariate sodalite zeolitic imidazolate frameworks: a direct solvent-free synthesis

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Zeolitic Imidazolate Frameworks (ZIFs) are a class of metal-organic frameworks with diverse applications.
• Achieving specific topologies like sodalite (SOD) in ZIFs, especially mixed-ligand systems, is synthetically challenging.
• Conventional methods often struggle to produce mixed-ligand ZIFs with desired structures.

Purpose of the Study:

• To develop a novel solvent-free synthetic methodology for mixed-ligand ZIFs.
• To explore the formation of sodalite topology (SOD) in mixed-ligand ZIFs, isoreticular to ZIF-8.
• To demonstrate the versatility of the method using various metal centers and ligands.

Main Methods:

• Solvent-free synthesis.
• Utilized three different metal centers: Zinc (Zn), Cobalt (Co), and Iron (Fe).
• Employed binary combinations of three distinct imidazole-based ligands: 2-methylimidazole, 2-ethylimidazole, and 2-methylbenzimidazole.

Main Results:

• Successfully synthesized mixed-ligand ZIFs with sodalite topology using a solvent-free approach.
• Demonstrated the formation of SOD frameworks for all three metal centers with a specific ligand combination (2-ethylimidazole and 2-methylbenzimidazole).
• Theoretical calculations confirmed the SOD topology as the most stable structure upon ligand mixing.

Conclusions:

• The developed solvent-free method is effective for creating mixed-ligand ZIFs with sodalite topology.
• Ligand mixing, particularly with 2-ethylimidazole and 2-methylbenzimidazole, is crucial for achieving the SOD topology across different metal centers.
• This work expands the synthetic accessibility of complex ZIF structures with potential for various applications.