Porous Zn(II)-Based Metal–Organic Frameworks Decorated with Carboxylate Groups Exhibiting High Gas Adsorption and Separation of Organic Dyes

Three new three-dimensional (3D) porous Zn(II)-based metal–organic frameworks (MOFs), namely, [Zn4O(L)2(NMP)2(H2O)]·2NMP·2H2O (1), [Zn(HL)(bpe)0.5]·DMF·H2O (2), and [Zn(HL)(bipy)0.5]·DMF·H2O (3) [bpe = 1,2-di(pyridin-4-yl)ethene, and bipy = 4,4′-bipyridine], were successfully synthesized by 5′-carboxyl-(1,1′-3′,1″-terphenyl)-4,4″-dicarboxylic acid (H3L). Sing-crystal X-ray diffraction shows that complex 1 is a twofolded interpenetrated 3D framework possessing the [Zn4O(COO)6] secondary building units (SBUs), and complexes 2 and 3 are two 3D isostructural networks with different N-donor ancillary ligands, where the partly deprotonated HL2– ligands are included. Gas adsorption behaviors of 1 to 3 for N2, CH4, and CO2 have been studied in detail at different temperatures, indicating that the high uptake and selectivity for CO2 will make it as potential gas storage and separation materials. Significantly, complexes 2 and 3 also exhibit the good organic dye selection and adsorption capacity, and the Congo red (CR) and methylene blue (MB) can be separated successfully by 2 in a very short time.