Amino-functionalized cerium based MOF for sustainable CO2 fixation into cyclic carbonates

Abstract

The conversion of CO₂ into valuable chemicals is a pivotal strategy to mitigate environmental and energy challenges. In this context, we report the design and synthesis of a cerium-based metal–organic framework {[Ce(L-NH₂)_0.5(NO₃)(H₂O)₂]·2DMF} (Ce-TPTC-NH₂), constructed from Ce(III) centers and a precisely engineered amino-functionalized terphenyl tetracarboxylate ligand {L-NH₂} (TPTC-NH₂). This crystalline, microporous framework not only exhibits excellent catalytic performance in the solvent-free cycloaddition of CO₂ with suitable epoxides, achieving >99% conversion under mild conditions (5 bar CO₂, 100 °C, 0.06 mol% catalyst) but also demonstrates unprecedented structural stability and reusability over multiple cycles. The synergistic interplay between Lewis acidic Ce³⁺ centers and basic –NH₂ groups enables enhanced activation of both CO₂ and epoxide substrates while lowering the activation barrier. Importantly, this Ce-MOF integrates bifunctional acid–base sites and is tailored specifically for CO₂ fixation. The catalyst retained its crystallinity and >90% activity after five cycles, confirming its practical viability. This work introduces a design pathway for amine-functionalized Ce-MOFs, showcasing their potential as highly efficient, stable, and reusable heterogeneous catalysts for CO₂ fixation under solvent-free conditions.