Solvents-Dependent Formation of Three MOFs from the Fe3O Cluster and 3,3′,5,5′-Diphenyltetracarboxylic Acid and Their Selective CO2 Adsorption

On the basis of the [Fe-3(mu(3)-O)(COO)(6)] cluster and 3,3',5,5'-diphenyltetracarboxylic acid (H4BPTC), three novel metal organic frameworks (MOFs), NJU-Bai25, NJU-Bai26, and NJU-Bai27 (NJU-Bai for Bai's group at Nanjing University) with different (4,4,4,6)-, (4,4,4,4,4,6)-, and (4,4,6)-connected nets were obtained in different solvent systems, in which due to the steric hindrance of the coordinated solvents the conformations of BPTC gradually change from the planar to the torsional; thus, the pore sizes of those MOFs were also gradually narrowed. Interestingly, the MOFs show high thermal/chemical stabilities and selective CO2 adsorption: NJU-Bai27 exhibits larger CO2 uptake (5.0 and 13.8 wt %) at 298 K under 0.15 and 1 bar, whereas NJU-Bai26 has a higher selectivity for CO2/N-2 (366).