Preparation of an interpenetrating bimetal metal-organic framework via metal metathesis used for promoting gas adsorption

Metal-organic frameworks (MOFs), which allow precise control over their porous environment, have attracted extensive research attention in the field of gas adsorption. In this study, an interpenetrating bimetal Cr-based MOF (termed MIL-126(Cr/Sc)) with trigonal-prismatic M3O (M = Cr/Sc, 61/39%) secondary building units has been synthesized using a metal metathesis method, and it retains the structure and porosity of the MIL-126(Sc) template and shows by far the highest thermal stability among the Cr-based tricyclic MOFs reported to date. Single component isotherm measurements have revealed that MIL-126(Cr/Sc) displays a higher CO2, N2O and C2H2 uptake under ambient conditions, and a larger gas uptake at low pressure when compared to pristine MIL-126(Sc). The results of our theoretical calculations indicated that the open Cr(iii) site had a stronger interaction with gas molecules than an open Sc(iii) site, thus promoting the gas capture capacity of MIL-126(Cr/Sc). These findings will facilitate further deliberate post-synthetic modifications of MOFs with open metal sites to promote their gas sorption capacity.