Synthesis, Structural Features, and Hydrogen Adsorption Properties of Three New Flexible Sulfur-Containing Metal-Organic Frameworks

Three novel flexible sulfur-containing MOF materials named Co-URJC-5, Cu-URJC-6 and Zn-URJC-7, based on the 5,5'-thiodiisophthalic acid linker have been synthesized through solvothermal methods and characterized by different physicochemical techniques. Hydrogen adsorption analysis at room temperature reveals that these compounds display a gate-opening type adsorption mechanism at low pressures, attributed to the flexible nature of the H4TBTC ligand. This behavior is even more noticeable for Cu-URJC-6, since the layer arrangement by p-p stacking interactions between the aromatic layers could contribute to the flexibility of the structure. These results can be considered as a representative example to elucidate how MOF structures are built using flexible ligands and more significantly as a promising route for designing materials with selective gas sorption properties.