Carbon dioxide from the combustion of fossil fuels is the primary contributor to climate change. Capturing CO₂ and using it, e.g., as a chemical feedstock could help to alleviate this problem. CO₂ can be converted into cyclic carbonates, for example. Existing heterogeneous catalysts for this type of reaction often require high temperatures and/or high CO₂ pressures. The development of improved catalysts is, thus, an interesting research target.

Lin Liu, Zheng-Bo Han, Liaoning University, Shenyang, China, and colleagues have synthesized a copper-based metal–organic polyhedron (MOP, pictured) with a high specific surface area and high CO₂ uptake. This MOP could be used as a heterogeneous catalyst for the chemical fixation of CO_2.

The team synthesized the metal–organic polyhedron by reacting Cu(NO₃)₂·3H₂O with 2,4,6-tris(3-carboxyphenoxy)-1,3,5-triazine (H₃TCPT) in a mixture of dimethylformamide (DMF) and CH₃CN at 75 °C. They obtained solvent adducts of [Cu₁₂(TCPT)₈(H₂O)₆(DMF)₆] as blue crystals. The copper-based polyhedra contain square-planar paddle-wheel-type Cu(II) clusters bridged by TCPT ligands.

The synthesized MOP has a high specific surface area of 407 m²g^–1 and high CO₂ uptake that corresponds to about 28 adsorbed CO₂ molecules per MOP unit. It also has a high density of  Lewis-acidic copper sites, which is promising for applications in catalysis. The team used it as a heterogeneous catalyst for the cycloaddition of CO₂ with epoxides to give cyclic carbonates and observed good performance under ambient conditions.

• A [(M₂)₆L₈] metal–organic polyhedron with high CO₂ uptake and efficient chemical conversion of CO₂ under ambient conditions,
  Li-Hua Liu, Lin Liu, Hao-Ran Chi, Chen-Ning Li, Zheng-Bo Han,
  Chem. Commun. 2022.
  https://doi.org/10.1039/d2cc01734b