Examinando por Autor "Montes-Andres, Helena"

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Novel and Versatile Cobalt Azobenzene-Based Metal-Organic Framework as Hydrogen Adsorbent
(Wiley, 2019-01-18) Montes-Andres, Helena; Leo, Pedro; Orcajo, Gisela; Rodríguez-Dieguez, Antonio; Choquesillo-Lazarte, Duane; Martos, Carmen; Botas, Juan Ángel; Martínez, Fernando; Calleja, Guillermo
A novel URJC-3 material based on cobalt and 5,5′-(diazene-1,2-diyl)diisophthalate ligand, containing Lewis acid and basic sites, has been synthesized under solvothermal conditions. Compound URJC-3, with polyhedral morphology, crystallizes in the tetragonal and P43212 space group, exhibiting a three-dimensional structure with small channels along a and b axes. This material was fully characterized, and its hydrogen adsorption properties were estimated for a wide range of temperatures (77–298 K) and pressures (1–170 bar). The hydrogen storage capacity of URJC-3 is quite high in relation to its moderate surface area, which is probably due to the confinement effect of hydrogen molecules inside its reduced pores of 6 Å, which is close the ionic radii of hydrogen molecules. The storage capacity of this material is not only higher than that of active carbon and purified single-walled carbon nanotubes, but also surpasses the gravimetric hydrogen uptake of most MOF materials.
Synthesis, Structural Features, and Hydrogen Adsorption Properties of Three New Flexible Sulfur-Containing Metal–Organic Frameworks
(American Chemical Society, 2020-08-31) Montes-Andres, Helena; Leo, Pedro; Orcajo, Gisela; Rodríguez-Dieguez, Antonio; Choquesillo-Lazarte, Duane; Martos, Carmen; Botas, Juan Ángel; Calleja, Guillermo
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 π–π 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.