Examinando por Autor "Choquesillo-Lazarte, Duane"

Mostrando 1 - 4 de 4

A double basic Sr-amino containing MOF as a highly stable heterogeneous catalyst
(Royal Society of Chemistry, 2019-07-03) Leo, Pedro; Orcajo, Gisela; Briones, David; Rodríguez-Dieguez, Antonio; Choquesillo-Lazarte, Duane; Calleja, Guillermo; Martínez, Fernando
A novel metal–organic framework (MOF) based on strontium alkaline-earth metal and 2-amino-1,4-benzenedicarboxylic acid (NH2-bdc) has been developed. This material is formed by a linear succession of face-sharing strontium polyhedra bridged by an organic ligand molecule to give a three-dimensional network with rhombohedral one-directional channels. This MOF is stable in polar organic solvents and up to 250 °C. The basic catalytic activity of both strontium metal nodes and amino groups of the ligand was tested in Knoevenagel condensation reactions. The influence of the temperature and reaction solvent over the catalytic performance of the MOF catalyst was demonstrated. The strontium/amino-containing MOF material evidenced a remarkable activity as compared to other conventional alkaline oxides typically used as reference basic solid catalysts. The novel MOF material showed remarkable activity and structural stability during five consecutive catalytic runs with no evidence of activity loss under the best reaction conditions found in this study.
A novel Zn-based-MOF for efficient CO2 adsorption and conversion under mild conditions
(Elsevier, 2021) Tapiador, Jesús; Leo, Pedro; Rodríguez-Diéguez, Antonio; Choquesillo-Lazarte, Duane; Calleja, Guillermo; Orcajo, Gisela
A novel Zn-based-MOF material, called Zn-URJC-8, containing two different organic linkers, 2-aminoterephtallic acid and 4,4-bipyridyl, has been synthetized and used for catalytic purposes for the first time. The structure of Zn-URJC-8 has been determined by single-crystal X-ray diffraction (XRD) showing -NH2 groups inward-facing of narrow pores, providing the material with excellent properties as CO2 adsorbent. The good results obtained by means of carbon dioxide adsorption isotherms have demonstrated the high interaction between CO2 and -NH2 groups with a Qst value of 54 kJ/mol at low coverage. The Zn-URJC-8 material also display promising results as catalyst for CO2 transformation in added value products. Almost complete conversion of epichlorohydrin and CO2 in cycloaddition reaction has been achieved under mild conditions, and the influence of different radical groups coordinated to the epoxides has been evaluated on the reaction yield. The recyclability has been also tested and the structural integrity of the catalyst is maintained after several consecutive reaction cycles.
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.