Noble metal-free Cu(i)-anchored NHC-based MOF for highly recyclable fixation of CO2 under RT and atmospheric pressure conditions

Abstract

The utilization of CO₂ as a C1 feedstock for the synthesis of high-value chemicals and fuels is an important step towards mitigating the increasing concentration of atmospheric carbon dioxide as well as the production of value-added chemicals. Herein, we demonstrate the development of an efficient recyclable catalyst for the conversion of CO₂ into oxazolidinones, which are important commodity chemicals for antibiotics, by utilizing an N-heterocyclic carbene (NHC)-based metal–organic framework (MOF). The NHC-centers lined in the pore walls of the MOF were utilized to anchor catalytically active Cu(I) ions by post-synthetic modification (PSM). The Cu(I)-embedded MOF showed highly recyclable and selective CO₂ uptake properties with a high heat of interaction energy of 43 kJ mol⁻¹. The presence of a high density of CO₂-philic NHC and catalytic Cu(I) sites in the 1D channels of the MOF render highly efficient catalytic activity for fixation of CO₂ into α-alkylidene cyclic carbonates and oxazolidinones at RT and atmospheric pressure conditions. Notably, Cu(I)@NHC–MOF showed excellent recyclability for up to 10 cycles of regeneration with retention of catalytic activity as well as chemical stability. To the best of our knowledge, Cu(I)@NHC–MOF is the first example of a noble metal-free MOF-based heterogeneous catalyst for the utilization of CO₂ to synthesize important value-added chemicals under mild conditions.