Three Robust Isoreticular Metal-Organic Frameworks with High-Performance Selective CO Capture and Separation.

Based on the hard-soft acid base (HSAB) theory, three robust isoreticular metal-organic frameworks (MOFs) with topology were successfully synthesized by solvothermal reaction {[InO(BHB)(HO)]NO·3DMA (), [FeO(BHB)(HO)]NO (), and [FeNiO(BHB)(HO)] () (DMA = ,-dimethylacetamide, HBHB = 4,4″-benzene-1,3,5-triyl-hexabenzoic acid)}. Both and are cationic frameworks, and their BET surface areas are 301 and 446 m/g, respectively. By modification of the components of metal clusters, features a neutral framework, and the BET surface area is increased up to 808 m/g. All three MOF materials exhibit high chemical and thermal stability. remains stable for 24 h at pH values ranging from 1 to 11, while and persist to be stable for 24 h at pH from 1 to 12. exhibits thermal stability up to 350 °C, whereas and can be stable up to 300 °C. Thanks to the microporous cage-based structure and abundant open metal sites, , , and have excellent CO capture capacity (28.0, 51.5, and 99.6 cm/g, respectively, under 298 K and 1 bar). Interestingly, the ideal adsorption solution theory results show that all three MOFs exhibit high separation selectivity toward CO over N (35.2, 43.2, and 43.2 for CO/N = 0.15/0.85) and CO over CH (14.4, 11.5, and 10.1 for CO/CH = 0.5/0.5) at 298 K and 1 bar. Thus, all three MOFs are potential candidates for CO capture and separation. Among them, displays the best separation potential, as revealed by dynamic column breakthrough experiments.