Supramolecular self-assembly structures from a di-Au(I) complex with a hinge-shaped ligand

Póster presentado en la XXXVII Reunión Bienal de la Real Sociedad Española de Química, celebrada en Donostia-San Sebastián (Spain) del 26 al 30 de mayo de 2019.Among N-heterocyclic carbenes (NHCs), polytopic NHC ligands have emerged as promising tools in the design of supramolecular structures.1 In this regard, our group of research designed fusedbis(imidazolinylidene) ligands with folded geometry and reported their coordination to Rh and Ir,2-3 and Pd.3 More recently, one of these hinge-shaped ligands allowed us to prepare the Au(I)-based dimetallic complex 1 (Scheme 1)

Redox-Switchable Cycloisomerization of Alkynoic Acids with Napthalenediimide-Derived N-Heterocyclic Carbene Complexes

Two naphthalene-diimide (NDI) bis-imidazolium salts have been used as N-heterocyclic carbene (NHC) precursors for the preparation of NDI-functionalized complexes of rhodium and iridium of general formula [MCl(NDI-NHC)(COD)] (M=Rh, Ir; NDI-NHC=NDI-functionalized NHC ligand). Comparison of the IR spectra of the complexes [IrCl(NDI-NHC)(CO)2] and their related one- and two-electron reduced forms, reveal that each one-electron reduction produces a decrease of the average ν(CO) of 9–10 cm−1, indicating a significant enhancement of the electron-richness of the metal. The [MCl(NDI-NHC)(COD)] complexes were tested in the catalytic cycloisomerization of alkynoic acids. The one-electron reduced forms showed greatly enhanced activities. For the cyclization of 5-hexynoic acid, the two-electron reduction of the ligand produced further enhancement of the catalytic activity, therefore showing that the catalyst can switch between three redox species with three distinct catalytic activities.Funding for open access charge: CRUE-Universitat Jaume IFunding for open access charge: CRUE-Universitat Jaume IWe gratefully acknowledge financial support from the Ministerio de Ciencia y Universidades (PGC2018-093382-B-I00), Generalitat Valenciana (AICO/2019/149), and the Universitat Jaume I (UJI-B2017-07 and UJI-B2018-46). S.G. thanks the Juan de la Cierva Incorporación program (IJC2019-039982-I). We are grateful to the Serveis Centrals d'Instrumentació Científica (SCIC-UJI) for providing with spectroscopic facilities

Effect of vanadium carbide on dry sliding wear behavior of powder metallurgy AISI M2 high speed steel processed by concentrated solar energy

Mixtures of AISI M2 high speed steel and vanadium carbide (3, 6 or 10 wt.%) were prepared by powder metallurgy and sintered by concentrated solar energy (CSE). Two different powerful solar furnaces were employed to sinter the parts and the results were compared with those obtained by conventional powder metallurgy using a tubular electric furnace. CSE allowed significant reduction of processing times and high heating rates. The wear resistance of compacts was studied by using rotating pin-on-disk and linearly reciprocating ball-on-flat methods. Wear mechanisms were investigated by means of scanning electron microscopy (SEM) observations and chemical inspections of the microstructures of the samples. Better wear properties than those obtained by conventional powder metallurgy were achieved. The refinement of the microstructure and the formation of carbonitrides were the reasons for this.JCCM in the Spanish National Programme (Project PPIC10-0052-5968

Facile Surfactant-Assisted Synthesis of BiVO4 Nanoparticulate Films for Solar Water Splitting

Bismuth vanadate (BiVO4), which has attractive applicability as a photoactive material, presents applications that range from catalysis to water treatment upon visible light irradiation. In this study, we develop a simple synthesis of < 200 nm monoclinic BiVO4 nanoparticles, which were further deposited on transparent conductive substrates by spin coating and calcination, obtaining nanostructured films. The obtained nanostructured BiVO4 photoanodes were tested for water oxidation, leading to promising photocurrents exhibiting competitive onset potentials (~0.3 V vs. RHE). These nanoparticulate BiVO4 photoanodes represent a novel class of highly potential materials for the design of efficient photoelectrochemical devices

The role of crystal facets and disorder on photo-electrosynthesis

Photoelectrochemistry has the potential to play a crucial role in the storage of solar energy and the realisation of a circular economy. From a chemical viewpoint, achieving high conversion efficiencies requires subtle control of the catalyst surface and its interaction with the electrolyte. Traditionally, such control has been hard to achieve in the complex multinary oxides used in PEC devices and consequently the mechanisms by which surface exposed facets influence light-driven catalysts are poorly understood. Yet, this understanding is critical to further improve conversion yields and fine-tune reaction selectivities. Here, we review the impact that crystal facets and disorder have on photoelectrochemical reactivity. In particular, we discuss how the crystal orientation influences the energetics of the surface, the existence of defects and the transport of reactive charges, ultimately dictating the PEC activity. Moreover, we evaluate how facet stability dictates the tendency of the solid to undergo reconstructions during catalytic processes and highlight the experimental and computational challenges that must be overcome to characterise the role of the exposed facets and disorder in catalytic performance

Nucleotide sequence and transfer properties of two novel types of Actinobacillus pleuropneumoniae plasmids carrying the tetracycline resistance gene tet(H)

17 p.The aim of this study is to analyze the sequence and transfer properties of two tetracycline resistance plasmids found in clinical isolates of Actinobacillus pleuropneumoniae in order to assert their role in the spread of tetracycline resistenceS

Antimicrobial susceptibility patterns of Haemophilus parasuis from pigs in the United Kingdom and Spain

18 p.A total of 30 British and 30 Spanish Haemophilus parasuis isolates were tested for their susceptibility to 19 of the antimicrobials currently used in swine practice with a broth microdilution method in order to know the emergence of resistance against these compounds in this porcine pathogen. All the British isolates were susceptible to penicillin, ceftiofur, erythromycin, tilmicosin, enrofloxacin, and florfenicol, and most of them were susceptible to the remaining antimicrobials (the highest resistance rate found was of 20% to neomycin). In contrast, all the Spanish isolates were susceptible exclusively to florfenicol, and high proportions of resistance were encountered for penicillin, ampicillin, oxytetracycline, erythromycin, tilmicosin, tiamulin and trimethoprim + sulphamethoxazole; in addition, a bimodal or multimodal distribution, or tailing of Spanish isolates over the MIC range was observed for clindamycin, sulphonamides and tylosine tartrate, suggesting the development of acquired resistance. In addition, several multiresistance patterns were found among the Spanish isolates, 23.3% of them being resistant to at least eight antimicrobials, the same rate as that encountered for those being susceptible to all antimicrobials tested. This study showed that in general British H. parasuis isolates are susceptible to antimicrobial agents routinely used for treatment of porcine respiratory diseases; however, the Spanish isolates need a more continuous surveillance of their susceptibility patternsS

Synthesis and Characterization of Poly-NHC-Derived Silver(I) Assemblies and Their Transformation into Poly-Imidazolium Macrocycles

Part of the “RSEQ-GEQO Prize Winners” Special CollectionThree metallosupramolecular assemblies composed of two bis-NHCs and two silver atoms, [4](PF6)2, two tetra-NHCs and foursilver atoms, [7](PF6)4, and two tri-NHCs and three silver atoms[8](BF4)3, have been prepared. Assemblies [4](PF6)2and [7](PF6)4feature NHC ligands decorated with terminal olefin groups.Irradiation of [4](PF6)2yielded complex [5](PF6)2with twoterminal cyclobutane rings linking the two bis-NHC ligands.Liberation of the macrocyclic tetrakisimidazolium salt H4-6(PF6)4was achieved by reaction of [5](PF6)2with NH4Cl/NH4PF6. No [2+2] cycloaddition was observed upon irradiation of [7](PF6)4,apparently due to an unfavorable orientation of the olefingroups. Irradiation of complex [8](BF4)3with three internal pairsof olefin groups leads to [9](BF4)3as a mixture of two isomersthat differ on the relative orientation of the internal cyclobutanerings. Reaction of [9](BF4)3with NH4Cl/NH4BF4yields an isomermixture of the novel cage-line hexakisimidazolium salt H6-10(BF4)6Three poly-imidazolium salts with appended olefins were obtained. Subsequent reaction with Ag2O enabled the preparation of the related poly-NHC-derived silver assemblies, which, depending on the relative orientation of the pendant olefins, underwent [2+2] cyclization of the olefins upon irradiation. The macrocyclic poly-imidazolium salts can be achieved by de-metallation using NH4Cl.Funding for open access charge: CRUE-Universitat Jaume

La competitividad en la industria de la construcción en México

14 páginasEl sector de la construcción de México, depende de la eficiencia para satisfacer las necesidades actuales que reclama la sociedad para sustentar el crecimiento y el progreso que necesita. La construcción de la infraestructura del país ha sido casi detenida en las últimas tres décadas, habiendo rezago en el desarrollo social y económico, como consecuencia de la deficiente administración del país. En este sentdo, los factores para analizar son: Las necesidades y proyectos de infraestructura (carreteras, puertos y aeropuertos, agua, energía proyectos de apoyo); las firmas de ingeniería; las empresas constructoras; el financiamiento y las decisione