Two different pore architectures of cyamelurate-based metal-organic frameworks for highly selective CO₂ capture under ambient conditions

In the context of porous coordination materials toward CO₂ capture and separation, two new metal-organic frameworks termed IRH-6 and IRH-7 were synthesized with square and rhombic microchannel pores, respectively. These materials exhibit high CO₂ uptakes of 2.67 mol kg⁻¹ (IRH-6) and 2.78 mol kg⁻¹ (IRH-7) at 100 kPa and 298 K. Grand canonical Monte Carlo simulation demonstrated strong non-covalent interactions between quadripolar CO₂ molecules and these nitrogen-rich frameworks. CO₂/CH₄ (50 : 50), CO₂/N₂ (15 : 85), and CO₂/H₂ (15 : 85) gas mixtures were investigated by ideal adsorbed solution theory and showed excellent CO₂ selectivity under ambient conditions for both porous materials. In particular, a remarkable increase in the CO₂ selectivity to 102 for IRH-7 over 31 for IRH-6 was observed for the CO₂/CH₄ binary mixture, which highlights the effect of pore aperture modification on preferential CO₂ uptake over other conventional gases.