Radii-dependent self-assembly polynuclear lanthanide complexes as catalysts for CO2 transformation into cyclic carbonates

Abstract

Multidentate acylhydrazone ligand dinuclear and pentanuclear complexes were constructed with the lighter lanthanide ions (La³⁺, Pr³⁺, and Eu³⁺) and the heavier lanthanide ions (Tb³⁺ and Er³⁺), respectively, which indicated the structural change of polynuclear lanthanide complexes is controlled by the ionic radii of Ln³⁺ ions. In addition, these polynuclear lanthanide complexes as catalysts in combination with tetrabutylammonium bromide (TBAB) as a co-catalyst displayed excellent catalytic performance for CO₂ conversion to obtain cyclic carbonates with a wide scope of substrates and high selectivity under solvent-free conditions.