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

Abstract

To address the far‐reaching consequences of radioiodine contamination and CO2 emissions, heteroatom engineering in materials has emerged as a promising strategy. In this study, three thermally and chemically stable Mn‐based metal–organic frameworks (MOFs), 1–3, are synthesized using (i) a dicarboxylate ligand with an oxadiazole core, and (ii) nitrogen‐rich ligands with varying spacers between the bis(tridentate) ends. The incorporation of a heterocyclic core and nitrogen atoms enhances polarity, while Lewis acidity of Mn2+ ion strengthens small molecule interactions. The strong iodine uptake, both in vapor (2.9–2.2 g g−1) and aqueous phases (1.82–1.34 g g−1), underscores their effectiveness in radioactive iodine remediation. Notably, these selectively capture iodide ions even in the presence of competing anions. The polar nature of 1–3 is also evidenced by CO₂ [isosteric heat of adsorption (Qst): 30 kJ mol−1] and H2O (uptake range: 7.77–11.48 mmol g−1) sorption studies. Exploiting their Lewis acidity and polar sites, 1–3 efficiently catalyze a solvent‐free CO2 fixation reaction with epoxide and aniline, yielding oxazolidinones with high conversions and turnover numbers. The configurational biased Monte Carlo (CBMC) simulations confirm interactions of 1–3 with ionic iodine and reactants of catalysis. These MOFs demonstrate excellent reusability, maintaining structural integrity without any metal leaching.