Cu(I)-Anchored NHC-Functionalized Covalent Organic Framework (COF) for Catalyzing CO ₂ Chemical Fixation into High-Value Compounds

Rapid urbanization has intensified global energy demands, leading to elevated carbon dioxide emissions. Therefore, capturing and utilizing CO₂ as a C1 feedstock is a viable way to synthesize value-added compounds while mitigating carbon emissions. Consequently, this study reveals the sensible design of an effective and highly reusable catalyst for efficiently exploiting CO₂ for the production of useful chemicals. For this, we designed an imidazole-based ionic COF (IL-COF), which was utilized to anchor eco-friendly alkynophilic, non-noble, Cu(I) metal ions to get an NHC (N-heterocyclic-carbene)-based covalent organic framework (COF), Cu(I)-NHC-COF. The catalyst showed outstanding performance for the transformation of CO₂ with propargylic alcohols to produce α-alkylidene cyclic carbonates (α-ACCs) and further promoted a one-pot, 3-component reaction of secondary amines and propargylic alcohols to obtain highly valuable β-oxopropylcarbamates. Additionally, the comprehensive theoretical investigations revealed the detailed reaction pathways for CO₂ coupling leading to the synthesis of α-ACCs and β-oxopropylcarbamates catalyzed by Cu(I)-NHC-COF. Moreover, NHC-COF presented excellent recyclability for several catalytic cycles without potential leaching and retained its chemical stability and catalytic activity. Overall, this study showcases a sustainable and green methodology of utilizing a noble-metal-free COF for the exploitation of CO₂ into high value carbamates and carbonates under ambient conditions.