Utility of Silver Nanoparticles Embedded Covalent Organic Frameworks as Recyclable Catalysts for the Sustainable Synthesis of Cyclic Carbamates and 2-Oxazolidinones via Atmospheric Cyclizative CO2 Capture

The present work introduces the favorable synthesis of porous functionalized nanomaterials with excellent surface area, porosity, and high CO2 capture ability to facilitate cyclizative reactions by incorporating the CO2 molecule into highly reactive organic moieties. We have attempted to fulfill the target by the decoration of Ag NPs over the exterior surfaces of covalent organic frameworks (COFs) TpPa-1 and TpTta to achieve Ag@TpPa-1 and Ag@TpTta nanomaterials with an absolutely ordered structure. Characterizations of the nanocatalysts (Ag@TpPa-1 and Agp TpTta) have been performed by field emission scanning electron microscopy, thermogravimetric tools, N-2 adsorption/desorption, transmission electron microscopy, Fourier transform infrared spectroscopy, UV-vis, and powder X-ray diffraction analysis. These Ag NPs architectured porous COFs described excellent performance for the benign synthesis of cyclic carbamates from unsaturated amines in the presence of N-iodosuccinimide (NIS) and several 2-oxazolidinone derivatives from propargylamine derivatives via cyclizative atmospheric CO2 capture under solvent-free and alkali-free conditions (sustainable approach). The microporous material Ag@TpTta revealed most excellent catalytic performance than Ag@TpPa-1 during production of cyclic carbamates and oxazolidinones which indicates that the selection of Ag NPs decorated COFs with the excellent surface area has a contributory effect on carboxylative cyclization reaction. Density functional theory studies furnished important information to establish the detailed mechanism of silver (0) catalyzed CO2 incorporation into unsaturated amine. These COFs enriched with N centers can interact with the Ag NPs at their outer exterior surfaces very tightly. These two nanocatalysts exhibited magnificent recycling efficiencies for the generation of cyclic carbamates and 2-oxazolidinones with almost zero silver leaching from the exterior part of the catalyst.