ABP y tics adaptados a los laboratorios de prácticas de química física: su inserción e implementación

El trabajo que se presenta está basado en la experiencia docente llevada a cabo en los grupos de laboratorio de las asignaturas Termodinámica Química y Experimentación en Química Física, de primer y segundo curso de la Licenciatura en Química. El objetivo principal de este trabajo ha sido demostrar que el hecho de emplear e integrar el Aprendizaje Basado en Problemas (ABP) como estrategia didáctica con las Tecnologías de la Información y Comunicación (TICs), es válido y aplicable a cualquier asignatura universitaria de índole práctica que implique a la Química Física.This work presents the obtained results on the context of two experimental subjects entitled Thermodynamic Chemistry and Physical Chemistry Laboratory. The principal goal is to show that the Problem Based Learning (PBL) technique integrated with the new technologies of virtual-teaching works efficiently as new methodologies of teaching Physical Chemistry at the university

Steric Tuning of Sulfinamide/Sulfoxides as Chiral Ligands with C1, Pseudo-meso, and Pseudo‑C2 Symmetries: Application in Rhodium(I)-Mediated Arylation

A new family of sulfinamide/sulfoxide derivatives was synthesized as chiral bidentate ligands by stereoselective additions of methylsulfinyl carbanions to N-tert-butylsulfinylimines. The new ligands, with C1, pseudo-meso, and pseudo-C2 symmetries, were successfully assayed in Rh-catalyzed additions of arylboronic acids to activated ketones. The sterically dissymmetric C1 ligand (RS,SC,RS)-N-[1-(phenylsulfinyl)-3-methylbut-2-yl] tert-butylsulfinamide turned out to be the optimal one, allowing the 1,4-additions of diverse arylboronic acids, on different α,β-unsaturated cyclic ketones with high chemical yields and enantioselectivities up to >99% ee.Ministerio de Economía y Competitividad (Grant CTQ2016-78580-C2-2R

The Role of the Interactions at the Tungsten Disulphide Surface in the Stability and Enhanced Thermal Properties of Nanofluids with Application in Solar Thermal Energy

Transition metal dichalcogenides (TMCs) exhibit unique properties that make them of interest for catalysis, sensing or energy storage applications. However, few studies have been performed into nanofluids based on TMCs for heat transfer applications. In this study, nanofluids based on 2D-WS2 are prepared by liquid phase exfoliation to analyze their potential usage in concentrating solar power plants. Periodic-Density Functional Theory (DFT) calculations were performed to rationalize the success of the exfoliation process. The hydrogen bond interaction between the hydroxyl group from PEG, which acts as a surfactant, and the S atoms of the WS2 surface stabilizes the nanosheets in the fluid. Electron localization function (ELF) analysis is indicative of the stability of the S-H interaction from WS2 with the molecules of surfactant due to the tendency to interact through weak intermolecular forces of van der Waals solids. Moreover, improvements in thermal properties were also found. Isobaric specific heat increased by up to 10% and thermal conductivity improved by up to 37.3%. The high stability of the nanofluids and the thermal improvements were associated with the high surface area of WS2 nanosheets. These results suggest that these nanofluids could be a promising heat transfer fluid in concentrating solar power plants

Revealing the role of Pb 2+ in the stability of organic–inorganic hybrid perovskite CH 3 NH 3 Pb 1− x Cd x I 3: an experimental and theoretical study

This paper presents the synthesis of organic–inorganic hybrid perovskite CH3NH3Pb1−xCdxI3. The effect of incorporating Cd2+ or Pb2+ on the stability of the perovskite structure was analysed from a theoretical and experimental viewpoint. The XRD results showed that the tetragonal perovskite structure was formed for x values of up to 0.5, which seems to indicate that the presence of a considerable amount of Pb2+ is necessary to stabilise the structure. In turn, UV-Vis spectroscopy showed how the presence of Cd2+ led to a reduction in the optical band gap of the perovskite structure of up to 9% for CH3NH3Pb0.5Cd0.5I3 with regard to the MAPbI3 structure. Moreover, periodic-DFT calculations were performed to understand the effect of the increased concentration of Cd on the structural and electronic properties of MAPbI3 perovskites. The analysis of both the ELF and the non-covalent interaction (NCI) index show the important role played by the Pb2+ ions in stabilizing this kind of hybrid perovskite structures. Finally, the DOS analysis confirmed the experimental results obtained using UV-Vis spectroscopy. The theoretical band gap values decreased as the concentration of Cd increased.Junta de Andalucía (P09- FQM-04938)Fondo Europeo de Desarrollo Regional (FEDER)Centro Informático Científico de Andalucía (CICA

Novel WS2-based nanofluids for concentrating solar power: performance characterization and molecular-level insights

Nano-colloidal suspensions of nanomaterials in a fluid, nanofluids, are appealing because of their interesting properties related to heat transfer processes. Whilst nanomaterials based on transition metal chalcogenides (TMCs) have been widely studied in catalysis, sensing, and energy storage applications, there are few studies of nanofluids based on TMCs for heat transfer applications. In this study, the preparation and analysis of nanofluids based on 2D-WS2 in a typical heat transfer fluid (HTF) used in concentrating solar power (CSP) plants is reported. Nanofluids prepared using an exfoliation process exhibited well-defined nanosheets and were highly stable. The nanofluids were characterized in terms of properties related to their application in CSP. The presence of WS2 nanosheets did not modify significantly the surface tension, the viscosity, or the isobaric specific heat, but the thermal conductivity was improved by up to 30%. The Ur factor, which characterizes the thermal efficiency of the fluid in the solar collector, shows an enhancement of up to 22% in the nanofluid, demonstrating great promise for CSP applications. The Reynolds number and friction factor of the fluid were not significantly modified by the addition of the nanomaterial to the HTF, which is also positive for practical applications in CSP plants. Ab initio molecular dynamics simulations of the nanoparticle/fluid interface showed an irreversible dissociative adsorption of diphenyl oxide molecules on the WS2 edge, with very low kinetic barrier. The resulting ‘decoration’ of the WS2 edge dramatically affects the nature of the interface interactions and is therefore expected to affect significantly the rheological and transport properties of the nanofluids

Interacciones por puente de hidrógeno y reacciones de transferencia protónica de la betacarbolina, 9H-Pirido (3,4-B)indol, y de sus derivados n-metilados con 1,1,1,3,3,3-hexafluoro-2-propanol en medios apróticos

Los resultados de nuestro estudio ponen claramente de manifiesto la compleja fotofísica del anillo de betacarbolina. Por una parte, la presencia de un átomo de nitrógeno piridínico y otro pirrólico con diferentes propiedades dadoras/aceptoras de puente de hidrógeno, proporciona al anillo de betacarbolina diferentes pautas de reactividad frente a aceptores/ dadores protónicos. Por otra parte, las diferentes estructuras electrónicas de estos dos centros conjugados permiten que se establezcan entre ellos procesos ICT. Ambas propiedades se ven drásticamente intensificadas tras la excitación por la luz. La estrategia seguida, consistente en bloquear por metilación los átomos de nitrógeno pirrólico y piridínico del anillo de betacarbolina, nos ha permitido controlar y modular las propiedades dadoras/aceptoras de puente de hidrógeno y los procesos ICT que determinan la reactividad de dicho anillo. Estos derivados metilados nos han proporcionado, además, los modelos adecuados para estudiar individualmente las propiedades espectrales y fotofísicas de las diferentes formas prototrópicas de la betacarbolina. Del estudio individualizado de cada uno de estos derivados se han extraido los resultados y conclusiones que han servido de base para interpretar el comportamiento de la propia BC

Pixel-Bit

Resumen basado en el de la publicaciónSe presenta una experiencia docente llevada a cabo en los grupos de laboratorio de las asignaturas de Termodinámica Química y Experimentación en Química Física, de primer y segundo curso de la Licenciatura en Química de la Universidad de Sevilla. Se pretende demostrar que el hecho de emplear e integrar el Aprendizaje Basado en Problemas (ABP) como estrategia didáctica, con las Tecnologías de la Información y la Comunicación (TIC), es válido y aplicable a cualquier asignatura universitaria de índole práctica que implique a la Química Física.AndalucíaES

ABP en laboratorios de Química Física Macromolecular

Archivo pdf destacando los criterios a seguir empleando la metodología ABP, los test de ideas previas, y proyectos a desarrollar en las sesiones prácticas.Se muestran el material docente elaborado y empleado en las prácticas de la asignatura Química Física Macromolecular del curso 2011/2012, empleando la metodología de Aprendizaje Basado en Problemas (ABP)Proyecto de Innovación y Mejora Docente PI1_12_01

A Theoretical Study on the Inclusion of Fe, Cu, and Zn in Illite Clays

The inclusion of Fe, Cu, and Zn in (1, 0, 0), (0, 0.5, 0), and (0.5, 0.5, 0.5) sites of an illite with the KAl2Si4O12H2 structure has been studied. For the inclusion of the metals, their common oxidation states were chosen, that is, 0, +2, +3 and 0, +1, +2, for Fe and Cu, respectively, while 0 and +2 for Zn. Periodic DFT calculations were performed to know the most favourable site of incorporation of the ions. Energetically the most favourable site for the inclusion corresponds to the (1, 0, 0) coordinate for all the ions independently of their oxidation state. However, the highest oxidation state of the metals (Fe3+, Cu2+, and Zn2+) was the most favoured for being incorporated into the illite structure and was the selected ion for the discussion. In those structures, metal oxygen interaction plays an important role in stabilizing the systems. Structural and energetic results indicate that illite presents good adsorption characteristic of those Fe3+, Cu2+, and Zn2+ in the (1, 0, 0) site. Thus, those ions may be available for plants for its extraction by phytoextraction techniques and the consequent soil regeneration. The inclusion of a second metallic ion revealed the most favourable inclusion corresponding to the inclusion of Fe3+ ion. The inclusion of this ion modifies the coordination sphere around the first metal being available for subsequent extraction by phytoremediation or other techniques for clean-up of the soil and its regeneration