Vol. 114 No. 4 (2018)

An Open Letter from Researchers to European Funding Agencies, Academies, Universities, Research Institutions, and Decision Makers

Bas de Bruin y otros 1.380 investigadores.

Resumen: La comprensión mecanística de los procesos catalíticos es de máxima relevancia. En este artículo se exponen las diferentes estrategias utilizadas para este fin, prestando especial atención a sustratos modelo que contienen grupos haluro de arilo o areno en un entorno macrocíclico utilizados de forma exitosa en procesos catalíticos que implican catalizadores de Cu, Ag, Au, Co y Ni. Se destaca la importancia de diseñar plataformas estructurales que sirvan como modelo para desentrañar detalles mecánisticos, a nivel molecular, de procesos de formación de enlaces C–C o C–heteroátomo catalizados por metales de transición. Este conocimiento servirá como base para el diseño de catalizadores más eficientes para una transformación deseada.
Palabras clave: diseño de ligandos, catalizadores de metales de transición, altos estados de oxidación, mecanismos, especies intermedias.
Abstract: Different approaches devoted to the mechanistic understanding of catalytic processes are exposed, paying special attention to the successful use of triazamacrocyclic aryl-halide or arene-containing substrates used for Cu-, Ag-, Au-, Co- and Ni-catalysis. The importance of designing model substrate platforms to unravel mechanistic details at a molecular level of C–C or C–heteroatom bond forming processes catalysed by transition metals are highlighted. This fundamental mechanistic knowledge will serve as a foundation for the catalyst design for a desired transformation.
Keywords: Ligand Design, Transition Metal Catalysts, High Oxidation States, Mechanisms, Intermediate Species.

Resumen: La aplicación de los distintos mecanismos de activación organocatalítica en química de cicloadición ha derivado en el desarrollo de diversas metodologías para la síntesis estereocontrolada de estructuras carbo- y heterocíclicas de relativa complejidad estructural de forma sencilla y eficaz. En este artículo se trata de ilustrar las posibilidades que ofrece la organocatálisis asimétrica como herramienta de síntesis a través de distintos ejemplos de reacciones de cicloadición desarrolladas en nuestro Grupo de Investigación, que van desde la paradigmática cicloadición Diels-Alder a otras cicloadiciones (formales) menos convencionales como las cicloadiciones (3+2), (5+2) o (4+3).
Palabras clave: Cicloadiciones, Organocatálisis, Catálisis Asimétrica, Heterociclos, Iluros.
Abstract: The application of the different organocatalytic activation manifolds in cycloaddition chemistry has led to the development of a variety of methodologies for the stereocontrolled synthesis of carbo- and heterocyclic scaffolds of relative structural complexity in a simple and effective manner. This account tries to illustrate the possibilities offered by asymmetric organocatalysis as a powerful synthetic tool through different examples of cycloaddition reactions developed in our research group, moving from the paradigmatic Diels-Alder cycloaddition to other less conventional (formal) cycloadditions such as (3+2), (5+2) or (4+3) cycloaddition reactions.
Keywords: Cycloadditions, Organocatalysis, Asymmetric Catalysis, Heterocycles, Ylides.

Non-covalent interactions unavoidably lead to an electron density redistribution of the molecular systems taking part in them. Quite importantly, even if these interactions are normally weak, they significantly perturb the intrinsic reactivity of the individual systems participating in them, which usually behave as Lewis bases or as Lewis acids. The consequence is that these electron density redistributions are mirrored in dramatic changes on the intrinsic acidity or basicity of the system acting as a Lewis acid or as a Lewis base, respectively, to the point that conventional bases become very strong acids, or conventional oxyacids become very strong bases. The aforementioned changes are particularly strong when the Lewis acids participating in the interaction are electron-deficient beryllium derivatives. This electron-deficient nature is also responsible for the behavior of some specific beryllium compounds as electron and anion sponges.

Keywords: instrinsic reactivity, non-covalent interactions, cooperativity, electron sponges, anion sponges, ion pairs

Resumen: Emergencia es el fenómeno a través del cual surgen fascinantes y nuevas propiedades. Este artículo tiene dos objetivos principales. El primero es presentar el fenómeno de emergencia usando el lenguaje de la química y empleando modelos químicos. El segundo y más importante objetivo, es resaltar la visión de que el aparente caprichoso movimiento de moléculas orgánicas y de agua puede, bajo condicio- nes de equilibrio, en un ambiente determinado, dar lugar a agrupamientos e interacciones que evolucionan hasta ordenarse en empaquetamientos estables, con propiedades que pueden ser valoradas como resultado de procesos emergentes.
Palabras clave: Emergencia, química, actividad biológica, auto-ensamblaje, agua, síntesis.
Abstract: Emergence is the phenomenon by which fascinating, and entirely novel properties, arise. This article has two major goals. The first is to present the phenomenon of emergence using the language of the chemistry and on the basis of chemical models. The second and more important goal is to make the point that the random motion of water and organic molecules under a conductive environment, involve shape interactions played our sequentially over time and can be considered also examples of emergent processes, where randomness can give rise to complex ordered structures.
Keywords: Emergence, chemistry, biological activity, self-assembly, water, synthesis.

This paper highlights the work of photographers that have contributed with an artistic vision to the graphic documentation of chemistry, through its protagonists, their laboratories, the substances, and their reactions. First a collection of portraits of famous chemists, made since the invention of the daguerreotype until the end of World War II, is reviewed. In second place, special attention is paid to the work of the German photographer Albert Renger-Patzsch, well known for his photographs of nature and urban and industrial architecture, but who has left us simple and fascinating images of glassware for the laboratory, as well as to the Northamerican science photographer Fritz Goro. Third, examples of photographers and scientists who have successfully illustrated several chemical reactions in books are given. Finally, brief comments are made on the work of photographers more related to physics, as well as that of other artists with scarce but interesting contributions in the field of chemistry.

Resumen: Atendiendo a las orientaciones metodológicas recogidas por los últimos Decretos que regulan los nuevos currículos de Secundaria derivados del cambio Legislativo en Educación, se desarrolla el tema de Cinética Química que se reincorpora al currículo de algunos cursos de Secundaria, contextualizando con el actual término de “Química Verde”, relacionado con el concepto de sostenibilidad. Concretamente se utilizará la catálisis y su importancia industrial como nexo de unión entre el currículo y el concepto de Química Verde.
Palabras clave: Enseñanza, Secundaria, Catálisis, Cinética Química, Química Verde.
Abstract: In regard with the methodological orientations gathered by the last Education Acts that regulate the new Secondary Education curricula derived from the Educative Laws changes, Chemical Kinetics is developed -which is reincorporated into the curriculum of some Secondary courses- in the context of the current term of “Green Chemistry”, related to the concept of sustainability. Specifically, catalysis and its industrial importance will be used as a link between the curriculum and the concept of Green Chemistry.
Keywords: Teaching, Secondary School, Catalysis, Chemical Kinetics, Green Chemistry.