Gridlike 3d-4f heterometallic macrocycles for highly efficient conversion of CO2 into cyclic carbonates

Abstract

Recycle CO2 as a chemical feedstock and as renewable energy generated sustainable solution benefiting both environment and economy. However, advancements in highly efficient CO2 conversion at ambient condition are still hampered, mainly due to the inherent thermodynamic stability of CO2 which lead to the low conversion efficiency and required harsh catalyzing conditions (high temperature, high pressure, and toxic solvents, etc.). In this study, two unique gridlike 3d-4f heterometallic structures Ln8Zn4L6 have been successfully constructed (Ln = Eu(1), Tb(2), H4L = 2,2'-oxybis (N'-((E)-2-hydroxy-3-methoxybenzylidene) acetohydrazide)). The multimetal centers and functional ligand within these Ln8Zn4L6 assembles greatly increased the efficiency of CO2 fixation and promoted the catalysis of CO2 at greener conditions like atmospheric pressure and solvent free. Meanwhile, such heterometallic design showed enhanced stability without being influenced by moisture and impurities. As a proof of concept, these catalysts were further applied in direct catalyzing the simulated flue gas (15 % CO2/85 % N2) in practice and successfully afforded the value-added cyclic carbonate in decent yields. Therefore, the design of such 3d-4f heterometallic macrocycles provided a general and efficient approach for realizing CO2 conversion at greener conditions, which showed great potential in the next generation of CO2 based sustainable chemistry.