Two Tb-metal organic frameworks with different metal cluster nodes for C2H2/CO2 separation

Through regulating the reaction solvent and temperature, two Tb-based metal–organic frameworks, ((CH3)2NH2)2[Tb9(μ3-OH)8(μ2-OH)3(PTB)6]·(DMF)14·(H2O)19 (1) and ((CH3)2NH2)3{[Tb9(μ3-O)2(μ3-OH)12(H2O)6][Tb3(μ3-O)(HCO2)3 (PTB)6]}·(DMF)12·(H2O)7 (2) (H3PTB = pyridine-2,4,6-tribenzoic acid), have been synthesized. Structural analysis showed that the cluster node of 1 is a Tb9 cluster, while 2 contains two different nodes of a Tb3 cluster and a Tb9 cluster, which leads to their different pore structures and may potentially separate C2H2/CO2. Gas adsorption demonstrates that both MOFs can separate C2H2 and CO2, but 2 has a more optimized pore environment than 1 and can exhibit better selective separation of C2H2/CO2.