CYCU-3: an Al(III)-based MOF for SO₂ capture and detection

Area of Science:

• Materials Science
• Chemistry
• Environmental Science

Background:

• Metal-Organic Frameworks (MOFs) are porous materials with potential applications in gas adsorption and sensing.
• Sulfur dioxide (SO2) is a harmful pollutant requiring effective capture and detection methods.

Purpose of the Study:

• To investigate the SO2 adsorption capabilities of the Al(III)-based MOF, CYCU-3.
• To explore the potential of CYCU-3 for SO2 detection applications.
• To elucidate the adsorption mechanism and fluorescence sensing mechanism of CYCU-3.

Main Methods:

• Gas adsorption isotherms at 298 K and 1 bar.
• Chemical stability tests under dry and wet SO2 exposure.
• Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) for adsorption site identification.
• Computational calculations (e.g., DFT) to understand adsorption mechanisms.
• Photoluminescence spectroscopy to evaluate SO2 detection performance and selectivity.
• Fluorescence mechanism investigation.

Main Results:

• CYCU-3 achieved a significant SO2 uptake of 11.03 mmol g-1.
• The material demonstrated high chemical stability towards SO2.
• Hydrogen bonding between SO2 and Al(III)-OH groups was identified as the primary adsorption mechanism.
• CYCU-3 exhibited selective SO2 detection with a turn-on fluorescence effect.
• Selectivity over CO2 and H2O was confirmed.
• A fluorescence mechanism involving ligand-metal energy transfer suppression and ligand-centered transitions was proposed.

Conclusions:

• CYCU-3 is a promising material for SO2 capture due to its high adsorption capacity and stability.
• The material's photoluminescent properties enable selective SO2 detection.
• The identified adsorption and fluorescence mechanisms provide insights for designing future MOF-based sensors and adsorbents.