Cu-NPs@COF: A potential heterogeneous catalyst for CO2 fixation to produce 2-oxazolidinones as well as benzimidazoles under moderate reaction conditions

Recently CO2 fixation has gained large extent attention due to its potential applications as an abundant C1 resource and variety of value-based fine chemicals that can be synthesized through this fixation. In this paper copper nanoparticles incorporated covalent organic framework based (Cu-NPs@COF) material was synthesized by a simple in-situ process. The material was characterized by various instrumental techniques such as FTIR spectra, PXRD, UV-vis spectra, HR-TEM, XPS, N-2 adsorption desorption, TG-DTA, AAS analysis, etc. The material is potentially very active catalyst in fixation of carbon dioxide to synthesize 2-oxazolidinones as well as benzimidazoles. 2-oxazolidinones was prepared from propergylamine in presence of 1,8-Diazabicyclo(5.4.0) undec-7-ene (DBU) base at 50 degrees C under 1 bar CO2 pressure in acetonitrile solvent medium and the desired product was obtained up to 96 % yield after 12 h of reaction. Again the catalyst can fix CO2 (1 bar pressure) in o-phenylenediamine/its derivatives to produce benzimidazoles with moderate to an excellent yield of the desired product in presence of environmentally benign hydrogen source dimethylamine borane (DMAB) under green solvent mixture (ethanol/water). Furthermore, the catalyst is very easily recyclable and reusable without considerable loss of active site copper metal for many catalytic cycles (up to six cycles was tested).