Showing papers by "Guillermo Mínguez Espallargas published in 2020"
TL;DR: The new cobalt metal-organic framework based on well-defined layered double cores that are strongly connected by intermolecular bonds has been developed and its high electrochemical efficiency suggests that the presence of nitrogen-containing aromatic equatorial ligands facilitates the water nucleophilic attack, as in the case of the highly efficient cobalt porphyrins.
Abstract: A new cobalt metal-organic framework (2D-Co-MOF) based on well-defined layered double cores that are strongly connected by intermolecular bonds has been developed. Its 3D structure is held together by π-π stacking interactions between the labile pyridine ligands of the nanosheets. In aqueous solution, the axial pyridine ligands are exchanged by water molecules, producing a delamination of the material, where the individual double nanosheets preserve their structure. The original 3D layered structure can be restored by a solvothermal process with pyridine, so that the material shows a "memory effect" during the delamination-pillarization process. Electrochemical activation of a 2D-Co-MOF@Nafion-modified graphite electrode in aqueous solution improves the ionic migration and electron transfer across the film and promotes the formation of the electrocatalytically active cobalt species for the oxygen evolution reaction (OER). The so-activated 2D-Co-MOF@Nafion composite exhibits an outstanding electrocatalytic performance for the OER at neutral pH, with a TOF value (0.034 s-1 at an overpotential of 400 mV) and robustness superior to those reported for similar electrocatalysts under similar conditions. The particular topology of the delaminated nanosheets, with quite distant cobalt centers, precludes the direct coupling between the electrocatalytically active centers of the same sheet. On the other hand, the increase in ionic migration across the film during the electrochemical activation stage rules out the intersheet coupling between active cobalt centers, as this scenario would impair electrolyte permeation. Altogether, the most plausible mechanism for the O-O bond formation is the water nucleophilic attack to single Co(IV)-oxo or Co(III)-oxyl centers. Its high electrochemical efficiency suggests that the presence of nitrogen-containing aromatic equatorial ligands facilitates the water nucleophilic attack, as in the case of the highly efficient cobalt porphyrins.
45 citations
TL;DR: High-quality crystalline layers with lateral sizes of 8 μm and thicknesses of 4 nm, which retain the structural integrity and magnetic properties, are obtained in a whole family of Fe-based magnetic MOFs, MUV-1-X.
20 citations
TL;DR: A series of hybrid organo-inorganic mononuclear lanthanoid complexes, denoted as LM4-1-Ln (Ln = DyIII, TbIII, EuIII, NdIII, ErIII, HoIII and GdIII), were synthesized via hydrothermal synthesis and were structurally characterized by X-ray diffraction as discussed by the authors.
Abstract: A series of hybrid organo–inorganic mononuclear lanthanoid complexes, [n-NBu4]3[LnH(PW11O39)(phen)2]·H2O, denoted as LM4-1-Ln (Ln = DyIII, TbIII, EuIII, NdIII, ErIII, HoIII and GdIII), were synthesized via hydrothermal synthesis and were structurally characterized by X-ray diffraction. The optical properties of all complexes have been investigated in the solid state. The temperature-dependent emission spectra of LM4-1-Dy, LM4-1-Tb and LM4-1-Eu complexes show intense lanthanoid emissions in the visible region, while LM4-1-Nd shows near-infrared (NIR) luminescence. The EuIII complex shows typical strong red emissions from the 5D0 → 7F0,1,2,3,4 transitions, with the CIE colour coordinates (0.631,0.364), the colour purity value of 83.9% and a quantum yield of up to 4.3%, suggesting that the organic fragment has an effect on the optical properties compared to fully inorganic systems, making this complex very attractive as a red component of light-emitting diodes. The luminescence decays of LM4-1-Dy, LM4-1-Tb and LM4-1-Eu exhibit a biexponential behaviour, with τAV = 4.1(7) μs, 0.35(2) ms and 0.94(3) ms, respectively. The values obtained for Judd–Ofelt intensity parameters Ω2 and Ω4 support the interaction between the EuIII and the ligands. Furthermore, those with ErIII and HoIII present weak emissions in the visible region. The T-dependent photoluminescence results show that the LM4-1-Dy, LM4-1-Tb and LM4-1-Nd complexes have good temperature sensitivity, demonstrating that the materials have the potential to be used as a sensing element for luminescent thermometers in different temperature ranges.
18 citations
TL;DR: The performance of this nanocomposite as an heterogeneous catalyst for hydrogenation of nitroarenes and nitrobenzene coupling with benzaldehyde has been evaluated, proving it to be an efficient and reusable catalyst.
Abstract: This work has been supported by the European Union (ERC‐2016‐CoG 724681‐S‐CAGE), by the Spanish MICINN (Structures of Excellence Severo Ochoa SEV‐2016‐0683 and Maria de Maeztu CEX2019‐000919‐M; projects CTQ2017‐89528‐P, CTQ2015‐67592, PGC2018‐097277‐B‐100, and RTI2018‐096399‐A‐I00 co‐financed by FEDER). We also thank the Generalitat Valenciana (PROMETEO/2018/006 and PROMETEU/2019/066). G.M.E. and P.O.‐B. thank MICINN for their “Ramon y Cajal” fellowships. M.G.‐M thanks support of a fellowship from “la Caixa” Foundation (LCF/BQ/PI19/11690022) and Generalitat Valenciana (SEJI/2020/036). J.M. thanks MICINN for his PhD fellowship (CTQ2015‐67592). The authors also thank the Electron Microscopy Service of Universitat Politecnica de Valencia for their support, M. P. Romero for her assistance with TEM measurements and Prof. E. Rodriguez‐Castellon for discussions on the XPS spectra interpretation. This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory and was supported by the U.S. DOE under contract no. DE‐AC02‐06CH11357, and the Canadian Light Source and its funding partners.
7 citations
TL;DR: In this paper, the formation and characterization of two novel Zn-based multifunctional metal-organic frameworks (MOFs) based on 1H-indazole-5-carboxylic acid and bipyridine-like linkers was reported.
Abstract: Herein we report the formation and characterization of two novel Zn-based multifunctional metal–organic frameworks (MOFs) based on 1H-indazole-5-carboxylic acid and bipyridine-like linkers, synthes...
6 citations