Cu(I)-Anchored NHC-Functionalized Covalent Organic Framework (COF) for Catalyzing CO2 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.