Zn(II)-Embedded Nanoporous Covalent Organic Frameworks for Catalytic Conversion of CO2 under Solvent-Free Conditions

Covalent organic frameworks (COFs) have been gaining substantial attention over the past decade due to their developing crystalline porous polymeric nature linked by strong covalent bonds and widespread applications in various fields. Currently, three-dimensional COFs (3D COFs) are engaging the spotlight due to their distinctive porous features, greater surface area, and exceptional performances in comparison with formerly published two-dimensional (2D) frameworks with the AA-stacking layered mode. In this paper, we present, for the first time, a nanoporous 3D-COF-based zinc(II) catalyst (Zn@RIO-1), which shows an efficient pathway for the chemical conversion of carbon dioxide to produce alpha-alkylidene cyclic carbonates and oxazolidinones from propargylic alcohols. The microporous material with a high surface area (312.61 m(2)/g) facilitates both types of catalytic reactions under atmospheric CO2 pressure. More importantly, easily recyclable and reusable catalysts produced moderate to high yields of desired carbonates as well as oxazolidinone products under solvent-free conditions. This study emphasizes the capability of nanoporous 3D-COF-based material in the catalysis field, more specifically in the field of CO2 capture and chemical fixation to fine chemicals. These results pave a spectacular pathway for the chemical fixation of CO2 into a-alkylidene cyclic carbonates and oxazolidinones from propargylic alcohols using 3D-COF as a potential heterogeneous ligand under sustainable conditions (i.e., solvent-free).

Automated summary

COFs have garnered attention for their crystalline porous polymeric nature and widespread applications, with 3D COFs now taking the spotlight for their unique features. This study introduces a nanoporous 3D-COF-based catalyst for the efficient chemical conversion of propargylic alcohols to alpha-alkylidene cyclic carbonates.