CYCU-3: an Al(III)-based MOF for SO 2 capture and detection.

The Al(III)-based MOF CYCU-3 exhibits a relevant SO ₂ adsorption performance with a total uptake of 11.03 mmol g ^-1 at 1 bar and 298 K. CYCU-3 displays high chemical stability towards dry and wet SO ₂ exposure. DRIFTS experiments and computational calculations demonstrated that hydrogen bonding between SO ₂ molecules and bridging Al(III)-OH groups are the preferential adsorption sites. In addition, photoluminescence experiments demonstrated the relevance of CYCU-3 for application in SO ₂ detection with good selectivity for SO ₂ over CO ₂ and H ₂ O. The change in fluorescence performance demonstrates a clear turn-on effect after SO ₂ interaction. Finally, the suppression of ligand-metal energy transfer along with the enhancement of ligand-centered π* → π electronic transition was proposed as a plausible fluorescence mechanism.