Electronic-State Localization Limits Charge Transport in a MIL-88B-Type Mixed-Valence Iron MOF

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer tunable properties for various applications.
• Mixed-valence metal nodes and redox-active ligands are key for electronic conductivity in MOFs.

Purpose of the Study:

• To synthesize and characterize a new MOF using a novel sulfonamide-terephthalate linker.
• To investigate the electronic transport properties of the resulting mixed-valence iron MOF.

Main Methods:

• Synthesis of 2,5-di(methylsulfonamido)terephthalic acid (H4-DSATA) linker.
• Incorporation of H4-DSATA into a MIL-88B-type mixed-valence iron MOF.
• Density Functional Theory (DFT) calculations to analyze electronic structure.

Main Results:

• A new MOF, [(Fe2+Fe3+2)(μ3-O)(H2-DSATA)3•3DMF], was successfully synthesized.
• The mixed-valence iron MOF demonstrated limited electronic transport.
• DFT analysis indicated strong electronic-state localization near Fe─O units as the cause.

Conclusions:

• The novel sulfonamide-terephthalate linker can be incorporated into MOFs.
• Electronic transport in this MOF is hindered by localized electronic states, despite the presence of mixed-valence iron centers and a redox-active ligand.