Bimetallic synergistic catalysis in MOFs toward transforming CO2 into carbonates with a record turnover number

Abstract

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  CuIn-CPT sets a record turnover number for asymmetric carbonate synthesis from CO₂
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  Synergistic catalysis ensures high efficiency and stability in multicomponent reactions
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  Bimetallic [Cu₄] and [In₃] clusters in MOFs drive tandem catalysis for CO₂ conversion

Transforming CO₂ into valuable asymmetric carbonates is crucial for green chemistry but remains challenging. This work presents a copper-indium framework that achieves record efficiency in synthesizing these compounds from CO₂ and alcohols under mild, solvent-free conditions. It maintains high stability, and the turnover number is much higher than that of reported noble metal catalysts. As the first metal-organic framework (MOF) catalyst for this reaction, it demonstrates the potential of non-precious metal systems in carbon utilization technologies.

The synthesis of asymmetric carbonates from renewable CO₂ is important for sustainable chemistry but often suffers from low efficiency, harsh reaction conditions, and noble metal catalysts. Achieving this efficient transformation under mild conditions by non-noble metal catalysts remains a great challenge. Herein, a framework {[In₃(μ₃-O)(H₂O)Cu₄(CPT)₄I₂]⋅(NO₃)⋅1.5H₂O⋅3DMF}_n (CuIn-CPT, CPT = 3,5-bis(4′-carboxyphenyl)-1,2,4-triazole) was synthesized, assembled from a [Cu₁₂In₁₈] nanocage with multiple Cu^I and In^III Lewis acid sites, and it exhibits good thermal and chemical stabilities. It achieves up to 98% yield in multicomponent reactions of CO₂, propargyl alcohols, and primary alcohols without solvent under mild conditions, with a record turnover number of 4,844—ten times higher than top Ag-based catalysts—and excellent recyclability over 10 cycles. Density functional theory (DFT) calculations and mechanistic studies confirm that the synergistic effect between [Cu₄] and [In₃] clusters enhances catalytic efficiency. This work provides an inspiration for developing efficient non-noble metal heterogeneous catalysts in CO₂ conversion.

The synthesis of asymmetric carbonates from renewable CO₂ is important for sustainable chemistry but often suffers from low efficiency, harsh reaction conditions, and noble metal catalysts. Achieving this efficient transformation under mild conditions by non-noble metal catalysts remains a great challenge. Herein, a framework {[In₃(μ₃-O)(H₂O)Cu₄(CPT)₄I₂]⋅(NO₃)⋅1.5H₂O⋅3DMF}_n (CuIn-CPT, CPT = 3,5-bis(4′-carboxyphenyl)-1,2,4-triazole) was synthesized, assembled from a [Cu₁₂In₁₈] nanocage with multiple Cu^I and In^III Lewis acid sites, and it exhibits good thermal and chemical stabilities. It achieves up to 98% yield in multicomponent reactions of CO₂, propargyl alcohols, and primary alcohols without solvent under mild conditions, with a record turnover number of 4,844—ten times higher than top Ag-based catalysts—and excellent recyclability over 10 cycles. Density functional theory (DFT) calculations and mechanistic studies confirm that the synergistic effect between [Cu₄] and [In₃] clusters enhances catalytic efficiency. This work provides an inspiration for developing efficient non-noble metal heterogeneous catalysts in CO₂ conversion.

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