CAU-52: An Iron Metal-Organic Framework Containing Furandicarboxylate Linker Molecules

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystallography

Background:

• Metal-organic frameworks (MOFs) offer tunable porosity and high surface areas for various applications.
• 2,5-furandicarboxylic acid (H2FDC), derived from lignocellulosic biomass, is a sustainable building block for MOFs.
• Iron-based MOFs are attractive due to iron's abundance and low toxicity.

Purpose of the Study:

• To synthesize and characterize a novel iron-based metal-organic framework (Fe-MOF) using H2FDC.
• To determine the crystal structure and porosity of the new Fe-MOF.
• To evaluate the gas sorption properties (N2 and H2O) and stability of the material.

Main Methods:

• Systematic screening of iron salts with H2FDC.
• Crystal structure determination using 3D electron diffraction (3D ED).
• Rietveld refinement against powder X-ray diffraction (PXRD) data.
• Gas sorption measurements (N2 at 77 K, H2O at 298 K).
• Thermal stability analysis (TGA in air).
• Chemical stability assessment in various solvents.

Main Results:

• Discovery and synthesis of a new Fe-MOF, CAU-52, with formula [Fe3(μ3-O)(FDC)3(OH)(H2O)2]·5H2O·H2FDC.
• CAU-52 features the trinuclear [Fe3(μ3-O)]7+ cluster and forms a pcu net with cubic cages.
• Nitrogen sorption at 77 K shows a type-I isotherm with a BET surface area of 1077 m²/g.
• Water sorption at 298 K exhibits a three-step isotherm with a capacity of 390 mg/g.
• CAU-52 demonstrates stability up to 250 °C in air and chemical resistance in common solvents.

Conclusions:

• CAU-52 is a novel, highly porous iron-based MOF derived from a biomass-accessible linker.
• The material exhibits promising properties for gas storage and separation applications.
• Its structural features and stability make it a candidate for further investigation in various chemical processes.