Rational Design of a Heterometallic Framework as a Highly Active Catalyst for Green Fixation of CO₂ under Moderate Conditions

Rational design of highly active noble-metal-free heterometallic catalysts for the green fixation of CO₂ into valuable chemicals is necessary and promising. Herein, a novel three-dimensional (3D) lanthanide-based copper-iodine cluster metal-organic framework has been harvested. Notably, benefiting from abundant Eu(III) and [Cu_<i>x</i>I_<i>y</i>] Lewis-acid active sites (<i>x</i> = 4, <i>y</i> = 3, 4), this compound reveals efficient catalytic performance (99%) and cyclicity in the carboxylative cyclization of both propargylic alcohols and propargylic amines with CO₂ under extremely mild conditions (room temperature and 1 bar) for 6 or 1.5 h, respectively. Furthermore, simulated flue gas with 13% CO₂ and large biological macromolecule substrates also can have good applicability, which may be attributed to the synergistic effect between Eu(III) and [Cu_<i>x</i>I_<i>y</i>] active sites as well as the nucleophilic cocatalyst. DFT (density functional theory) further revealed the activation of Cu(I) on C≡C bonds from propargylic alcohols and propargylic amines, providing theoretical guidance for the preparation of a novel catalytic material for CO₂ conversion.