Two comparable Ba-MOFs with similar linkers for enhanced CO2 capture and separation by introducing N-rich groups

Two new different metal–organic frameworks (MOFs) [Ba(L1)(H 2 O) 2 ] n · n H 2 O (MOF 1) and [Ba(L2)(H 2 O) 2 ] n ·0.5 n DMF·0.5 n H 2 O (MOF 2) were yielded by the assembly of oxygen-friendly Ba(II) ions and two similar linkers, namely 2-(imidazol-1-yl)terephthalic acid (H 2 L1) and 2-(1H-1,2,4-triazol-1-yl) terephthalic acid (H 2 L2). Single-crystal X-ray diffractions (XRD) indicate that MOF 1 is a new three-dimensional (3D) stacking dense network formed by the one-dimensional (1D) rod-shaped chains and L1 linkers, whereas MOF 2 presents a 3D nanotube porous framework with cylindrical tunnels based on the 1D loop chains as the secondary building units (SBUs) by replacing the imidazole group in H 2 L1 with the triazole group in H 2 L2. As a result, MOF 2 has a higher density of active sites and Lewis acid sites in the porous surface of nanotube than MOF 1. Thereby, the CO 2 capture and separation capacity of MOF 2 is great higher than that of CH 4 at 298 K.