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, [Zn 4 O(L) 2 (NMP) 2 (H 2 O)]·2NMP·2H 2 O ( 1 ), [Zn(HL)(bpe) 0.5 ]·DMF·H 2 O ( 2 ), and [Zn(HL)(bipy) 0.5 ]·DMF·H 2 O ( 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 (H 3 L). Sing-crystal X-ray diffraction shows that complex 1 is a twofolded interpenetrated 3D framework possessing the [Zn 4 O(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 HL 2– ligands are included. Gas adsorption behaviors of 1 to 3 for N 2, CH 4, and CO 2 have been studied in detail at different temperatures, indicating that the high uptake and selectivity for CO 2 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.