Examinando por Autor "Briones, David"

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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.
Direct α-arylation of ketones efficiently catalyzed by Cu-MOF-74
(Elsevier, 2019-09-19) Leo, Pedro; Orcajo, Gisela; Briones, David; Martínez, Fernando; Calleja, Guillermo
The activity and reusability of Cu-MOF-74 as heterogeneous catalyst were studied in the Cu-catalyzed CeC crosscoupling reaction of 4-iodotoluene (4-IT) with acetylacetone (AcAc) to direct synthesis of α-aryl-ketones. CuMOF-74 is characterized by having unsaturated copper sites into its highly porous metal-organic framework that can play a crucial role in catalytic applications. The influence of critical reaction variables such as solvent, reaction temperature, AcAc/4-IT ratio, catalyst concentration and basic agent (type and concentration) were evaluated. High conversions were achieved at 140°C, 5mol % of catalyst, AcAc/4-IT ratio of 2:1, DMF as solvent and 1.5 equivalent of Cs2CO3 base. The C-arylation between 4-IT and AcAc proceeded only in the presence of CuMOF-74 material, being very low the transformation in absence of the solid catalyst. Cu-MOF-74 material displayed a remarkable structural stability, regarding its XRD patterns and solid recovery degree after several reaction cycles, which was also complemented by the negligible amount of copper leached in the reaction media. This catalyst showed promising results in comparison to other homogeneous and heterogeneous Cu-based catalysts. This work evidences the great potential of MOF materials as heterogeneous catalysts in fine chemistry applications.