Lewis acid-promoted self-sensitized photocatalytic CO₂ reduction by a bimetallic Fe complex

The modified macrocyclic Mabiq ligand, ^MeOMbq, contains two methoxy groups at the outer biquinazoline unit that allow for coordination of a second metal ion in the absence of auxiliary ligands. A series of bimetallic MFe^MeOMbq complexes was synthesized, containing Na, Mg, Fe or Zn adjacent to a centrally bound ferrous ion. The redox properties correlate with the Lewis acidity of the supporting metal. Both Fe and Zn in the outer site boost the photocatalytic CO₂ reduction activity of the central ferrous site. The bimetallic ZnFe^MeOMbq achieves up to 140 TONs (1 h) for selective CO₂ to CO conversion in a self-sensitized process.