Engineering cost-effective N-rich metal-organic frameworks (MOFs) for highly efficient CO2 capture and its catalytic conversion to cyclic carbonates: A step towards sustainable carbon utilization

In an era where the optimization of CO2 stands at the frontier of sustainable chemistry, we unveil two architecturally rare, N-rich metal-organic frameworks (MOFs), {[Zn2(TATAB)2(Me3NH)2](H2O)2(CH3OH)2}n (ZS-2) and {[Cu2(TATAB)2(Me3NH)2](Me2NCHO)2}n (ZS-3), meticulously designed using a solvothermal route. These crystalline frameworks manifest a unique srs topology (3/10/c1 net), elevating them beyond the realm of conventional porous materials. BET analyses reveal remarkably high surface areas, with ZS-2 exhibiting 630.35 m2 g-1 and ZS-3 reaching 641.36 m2 g-1, together with narrow pore-limiting diameters of approximately 2.40 nm and 3.98 nm, respectively. These features underscore their mesoporous nature, rendering them highly suitable for selective molecular sieving and effective CO2 capture and fixation. ZS-3 shows a high CO2 uptake of 64 cm3 g-1, exceeding both ZS-2 (56 cm3 g-1) and many benchmark MOFs reported in the literature. XPS analysis confirms strong metal-CO2 interactions, as reflected by clear shifts in binding energies from 1022.08 to 1023.52 eV for Zn 2p and from 933.60 to 934.34 eV for Cu 2p, indicating strong chemisorptive affinity. Interestingly, ZS-2 exhibits better catalytic performance, with higher conversion efficiency, greater selectivity, and increased TON and TOF in CO2-epoxide cycloaddition under mild conditions at 1 atm and 60 °C. The captured CO2 was successfully converted into cyclic carbonates, as confirmed by 1H NMR spectroscopy.