624 research outputs found
3‐(Pyridin‐2‐yl)imidazo[1,5‐a]pyridine (Pyridylindolizine) as Ligand in Complexes of Transition and Main‐Group Metals
Producción CientíficaThe coordination of the easily prepared 3‐(pyridin‐2‐yl)imidazo[1,5‐a]pyridine (pyridylindolizine, Py‐indz) ligand to several metal moieties was studied, and its electronic properties, similar to those of the classical ligands 2,2′‐bipyridine (bipy) and 1,10‐phenanthroline (phen), are reported. The new complexes were prepared and fully characterized by X‐ray crystallography and other typical spectroscopic methods if possible. Paramagnetic complexes [Ni(S2X)2(Py‐indz)] X = P(OEt)2 (1), COEt (2); [Ni(acac)2(Py‐indz)] (3, acac = acetylacetonate); [Ni(Py‐indz)3](PF6)2 (4); [Mn2Cl4(Py‐indz)2] (6); and [MnCl2(Py‐indz)2] (7) have the magnetic moment expected for a metallic cation with two or five unpaired electrons. Diamagnetic complexes show NMR spectra with similar patterns with small differences depending on the complex. [M{S2P(OEt)2}2 (Py‐indz)] M = Zn (8), Cd (9) have pentacoordinate and hexacoordinate structures, respectively. Octahedral tin complexes [SnL4(Py‐indz)] L4 = I4 (10), Cl3Ph (11), and Cl2nBu2 (12) have different behaviors in solution; whereas complex 10 is practically insoluble, complex 11 displays the expected pattern in its NMR spectrum, and complex 12 shows dynamic behavior. The Py‐indz ligand is also able to stabilize copper(I) and forms [Cu(PPh3)2(Py‐indz)]BF4 (13). The synthesis of the carbonyl complexes [MBr(CO)3(Py‐indz)] M = Mn (14), Re (15) and [Mo(CO)4(Py‐indz)] (16) was followed by IR spectroscopy in solution. [RuCl·p‐cym(Py‐indz)]PF6 (17, p‐cym = p‐cymene) has the familiar half‐sandwich “three‐legged piano‐stool” geometry.Ministerio de Economía, Industria y Competitividad (Project CTQ2013- 41067-P
Copper Complexes in the Promotion of Aldol Addition to Pyridine-2-carboxaldehyde: Synthesis of Homo- and Heteroleptic Complexes and Stereoselective Double Aldol Addition
Producción CientíficaCuCl2·2H2O and Cu(ClO4)2·6H2O are able to promote aldol addition of pyridine-2-carboxaldehyde (pyca) with acetone, acetophenone, or cyclohexenone under neutral and mild conditions. The general and simple one-pot procedure for the aldol addition to Cu(II) complexes accesses novel Cu complexes with a large variety of different structural motifs, from which the aldol-addition ligand can be liberated by treatment with NH3. Neutral heteroleptic complexes in which the ligand acts as bidentate, or homoleptic cationic complexes in which the ligand acts as tridentate can be obtained depending on the copper salt used. The key step in these reactions is the coordination of pyca to copper, which increases the electrophilic character of the aldehyde, with Cu(ClO4)2 leading to a higher degree of activation than CuCl2, as predicted by DFT calculations. A regio- and stereoselective double aldol addition of pyca in the reaction of Cu(ClO4)2·6H2O with acetone leads to the formation of a dimer copper complex in which the novel double aldol addition product acts as a pentadentate ligand. A possible mechanism is discussed. The work is supported by extensive crystallographic studies.2019-12-312019-12-31Ministerio de Economía, Industria y Competitividad (Project CTQ 2013-41067-P
Preliminary evaluation of grain yield components in hexaploid tritordeum
Chromosome duplication of Hordeum chilense and Triticum turgidum conv. durum hybrids created a
new cereal with favorable characteristics for planting: the hexaploid tritordeum (X Tritordeum Ascherson et
Graebner). A field experiment with three replications was carried out in Cordoba, Spain, to obtain more information
on the potential yield of tritordeum for grain yield and its components. The performance of two advanced
tritordeums was compared with the yield of two commercial wheat varieties, two durum wheats and four triticales.
Results showed that tritordeum has a great potential for the development of highly productive varieties,
especially because it is a new and rarely bred specie
Synthesis of Enantiopure Oxygen- and Nitrogen-Containing Heterocycles by Diastereoselective Ring-Closing Metathesis Reaction in Perhydro-1,3-benzoxazine Derivatives
Producción CientíficaDiastereoselective ring‐closing metathesis reactions on chiral trienic perhydro‐1,3‐benzoxazines derived from (−)‐8‐aminomenthol featuring two diastereotopic olefin chains is described. The diastereochemical outcome of the cyclization appeared to be dependent on the length and position of the olefin chains in perhydro‐1,3‐benzoxazine, the degree of substitution of the double bonds and the ruthenium catalyst used. After separation of the diastereomers, and removal of the chiral auxiliary, enantiopure oxygen‐ and nitrogen‐containing heterocycles were obtained.Ministerio de Economía, Industria y Competitividad (Project FEDER-CTQ2014-59870-P)Junta de Castilla y León (Ref. Project FEDER-VA115P17
Electoral debates in the VODs of the Public RTVs of Europe
Introducción: En los medios públicos, el debate electoral es de especial interés por las reglas que deben adoptar estas televisiones para cumplir con sus compromisos de servicio público y mantener los valores de diversidad, universalidad y participación. En el nuevo escenario que plantean las plataformas propias de VOD la inclusión de estos debates electorales televisados y las variaciones en su formato se plantea como un ejercicio de transparencia y un compromiso con la memoria audiovisual del país que refuerza los valores de diversidad, proximidad y universalidad representativa. Metodología: El artículo revisa de un modo comparativo el uso de este formato en siete de las principales emisoras públicas de televisión de Europa siguiendo los modelos de Hallin y Mancini y con una subdivisión regional dentro del modelo democrático-corporatista para obtener resultados con un corte étnico-político. Resultados y conclusiones: Existe una notable disparidad entre las televisiones públicas que tienen accesibles los debates electorales en sus plataformas de VOD. El análisis desvela que, a pesar de su trascendencia, los debates no se encuentran disponibles en los entornos online del medio, aunque sí son accesibles desde plataformas ajenas, principalmente YouTubeEste artículo forma parte de las actividades del proyecto de investigación (RTI2018-096065-B-I00) del Programa Estatal de I+D+i orientado a los Retos de la Sociedad del Ministerio de Ciencia , Innovación y Universidades y del Fondo Europeo de Desarrollo Regional (FEDER) sobre Nuevos valores, gobernanza, financiación y servicios audiovisuales públicos para la sociedad de Internet: contrastes europeos y españoles. El autor Martín Vaz Álvarez es beneficiario de una ayuda de Formación de Profesorado Universitario del Ministerio de Ciencia, Innovación y Universidades de España (ref. FPU19/06204)S
Assembling Nonplanar Polyaromatic Units by Click Chemistry. Study of Multicorannulene Systems as Host for Fullerenes
Producción CientíficaNovel compounds with two or three corannulene subunits have been obtained by “click chemistry”. These exotic systems were synthesized in high yields using the ethynylcorannulene as common reagent. The synergistic action as receptors for fullerenes of several corannulene blocks has been evaluated. It was found that the three-armed derivatives showed efficient complexation abilities toward C60. Furthermore, a new compound having two corannulene subunits linked to a hexahelicene scaffold has a remarkable affinity constant. Finally, theoretical calculations have been performed to evaluate the formation of their relative adducts containing a C60 molecule.Ministerio de Economía, Industria y Competitividad (Projects 258 CTQ2013-41067-P and CTQ2011-23862-C02
Dimethylzinc-Mediated Addition of Phenylacetylene to α-Diketones Catalyzed by Chiral Perhydro-1,3-benzoxazines
Producción CientíficaAn efficient enantioselective Me2Zn-mediated mono addition of phenylacetylene to α-diketones in the presence of a chiral perhydro-1,3-benzoxazine ligand is described. At temperatures higher than -20 ºC a kinetic resolution of the resulting α-hydroxy ketone occurs which greatly improves the enantioselectivity although with moderate chemical yield. The alkynylation of nonsymmetrical aromatic diketones with electronically different substituents on the aromatic rings proceed with high regioselectivity. This procedure allows the preparation of α-hydroxy-α-ynyl-ketones as highly enantioenriched materials.2018-07-07Ministerio de Economía, Industria y Competitividad (Project CTQ2014-59870 P)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA064U13
Syntheses, solid structures, and behavior in solution of [MI2(CO)3(pyrazole)2] complexes (M = Mo, W)
Producción Científica[MI2(CO)3(pz*H)2] complexes (M = Mo, W; pz*H = pzH, dmpzH, indzH) have been synthesized and characterized in solid state and in solution. These heptacoordinated complexes present a capped octahedron geometry in the solid state where the azole ligands are always coordinated pseudo-cis, and the iodido ligands are coordinated either pseudo-trans (pzH complexes and molybdenum complex with indzH) or pseudo-cis (tungsten complex with dmpzH). Both isomers are found in the crystal structure of [WI2(CO)3(indzH)2]. The difference in energies between both isomers have been theoretically calculated and range between −2.9 and +1.0 kcal/mol. The complexes where the iodido ligands are coordinated pseudo-trans show unequivalent azoles in the NMR at low temperature while they undergo a dynamic process in solution which makes both heterocycles equivalent at room temperature. The other complexes display a dynamic behavior in solution where both heterocycles are equivalent both at room and at low temperatures.Ministerio de Economía, Industria y Competitividad (Project CTQ2013-41067-P
Eurydice read the draft white paper about the role of no university teaching function (MECD II): Continuous teacher training, teacher evaluation, working conditions and supplements and incentives
En este segundo artículo la Unidad Española de Eurydice analiza la formación continua del profesorado en los siguientes aspectos: las necesidades expresadas por los profesores y la respuesta dada en los distintos sistemas educativos europeos, la participación de los docentes y su relación con las necesidades expresadas, y las motivaciones e impedimentos para dicha participación. También se analiza la evaluación que hacen los profesores, apreciando diferencias y similitudes en los enfoques, modelos, fuentes de información y resultados. A continuación se detallan las condiciones laborales del profesorado partiendo de las modalidades de ingreso y de contratación; los salarios oficiales y reales y su relación con el PIB per cápita, con la antigüedad en la carrera docente o con las condiciones de jubilación disponibles y con otros aspectos vinculados más directamente al desempeño diario: horarios laborales y lectivos, ratios de alumnos o disponibilidad de profesionales de apoyo en los centros. Para terminar, se informa sobre la existencia de complementos e incentivos tanto económicos como de ascenso profesional, de formación y desarrollo profesional continuosIn this second article the Spanish Unit of Eurydice analyses the continuous training of the teachers in the following aspects: the needs expressed by the teachers and the response offered by the different European education systems, the teachers´ commitment and their relation to the expressed needs and the motivations and obstacles of this commitment. The evaluation done by the teachers is also analysed, assessing the differences and similarities in the approaches, models, information sources and results. Then the working conditions of the teachers are described starting with the entry and recruitment procedures; the official and real salaries and their relation with the GDP per capita and the length of service or the available retirement conditions and other aspects related with the daily work: the work schedules and the lecture timetables, students´ ratio or the availability of support assistants in the education centres. It finishes informing about the income supplements and the economic and career development incentives, with continuous training and professional improvemen
Musculoskeletal Pain and Non-Classroom Teaching in Times of the COVID-19 Pandemic: Analysis of the Impact on Students from Two Spanish Universities
[EN] The lockdown, due to the coronavirus, has led to a change in lifestyle and physical activity in Spanish university students. The objective of this study was to analyze the prevalence of musculoskeletal pain and changes in physical activity and self-perceived stress in the student bodies of two Spanish Universities during the lockdown. A cross-sectional study was carried out in a sample of 1198 students (70.6% women). The main instruments used for measuring were the Standardized Kuorinka Modified Nordic Questionnaire and the Perceived stress scale (the questionnaire regarding the practice of physical activity). A reduction in the prevalence of musculoskeletal pain (p < 0.001) was identified in the sample of men and women, an increase (12.5%) in the frequency of carrying out physical activity from moderate to frequent, and the preference for strength training (15.1%), especially among women, was identified. All of this may be taken into account by health institutions when implementing measures to encourage physical activity in both suitable amounts and types, which improves the quality of life of the students.S
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