Nitrogen-Rich Mn-Based Metal-Organic Frameworks for Small Molecule Adsorption and Activation through Polarization

Area of Science:

• Materials Science
• Environmental Chemistry
• Catalysis

Background:

• Radioiodine contamination and CO₂ emissions pose significant environmental challenges.
• Heteroatom engineering in materials offers a promising strategy for remediation and carbon capture.
• Metal-organic frameworks (MOFs) are versatile porous materials with tunable properties.

Purpose of the Study:

• To synthesize novel Mn-based MOFs for radioactive iodine remediation and CO₂ capture.
• To investigate the catalytic activity of these MOFs in CO₂ fixation reactions.
• To evaluate the stability, reusability, and interaction mechanisms of the synthesized MOFs.

Main Methods:

• Synthesis of three thermally and chemically stable Mn-based MOFs (1-3) using specific dicarboxylate and nitrogen-rich ligands.
• Sorption studies for iodine (vapor and aqueous phases), CO₂, and H₂O.
• Catalytic evaluation of MOFs in a solvent-free CO₂ fixation reaction with epoxides and anilines.
• Configurational biased Monte Carlo (CBMC) simulations to confirm interactions.

Main Results:

• MOFs 1-3 exhibit strong iodine uptake (2.9-2.2 g g⁻¹ in vapor, 1.82-1.34 g g⁻¹ in aqueous phases) and selective capture of iodide ions.
• High CO₂ adsorption (Qst: 30 kJ mol⁻¹) and H₂O uptake (7.77-11.48 mmol g⁻¹) demonstrate the polar nature and gas sorption capabilities.
• Efficient catalysis of CO₂ fixation yielding oxazolidinones with high conversions and turnover numbers, with excellent reusability and no metal leaching.

Conclusions:

• The synthesized Mn-based MOFs are highly effective for radioactive iodine remediation due to their strong uptake and selectivity.
• These MOFs demonstrate significant potential for CO₂ capture and utilization, evidenced by sorption studies and catalytic performance.
• The materials exhibit excellent stability and reusability, making them promising candidates for practical environmental and catalytic applications.