An Iron Bis(carbene) Catalyst for Low Overpotential CO2 Electroreduction to CO: Mechanistic Insights from Kinetic Zone Diagrams, Spectroscopy, and Theory

A common challenge in molecular electrocatalysis is the relationship between maximum activity and the overpotential required to reach that rate, with faster catalysts incurring higher overpotentials. This work follows a strategy based on independent tuning of ligands in the primary coordination sphere to discover a previously unreported iron catalyst for CO2 reduction with higher activity than similar complexes while maintaining the same overpotential. Iron complexes bearing a bis-N-heterocyclic carbene ligand (methylenebis(N-methylimidazol-2-ylidene), bis-mim) and a redox active 2,2′:6′,2″-terpyridine (tpy) ligand were synthesized and found to catalyze the selective reduction of CO2 to CO at low overpotential with water as the proton source. Mechanistic studies based on kinetic zone diagrams, spectroscopy, and computation enable comparisons with a previously studied pyridyl–carbene analogue. Changing the bidentate ligand donor ability accelerates catalysis at the same overpotential and changes the nature of the turnover-limiting step of the reaction.The synthesis, voltammetry, and spectroelectrochemistry were supported as part of the Alliance for Molecular PhotoElectrode Design for Solar Fuels (AMPED), an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001011 (E.A.A and A.J.M.M). Jordi Benet assisted with crystallographic data collection. Brandie M. Ehrmann assisted with mass spectrometry. The mass spectrometry work was supported by the National Science Foundation under grant no. (CHE-1726291). Computational studies, flow electrolyses, and X-ray diffraction studies were supported by the European Commission for the ERC-CoG-2015-648304 project and the Spanish Ministry of Science for the project PID2019-110050RB-I00 (J.Ll.-F). S.G. thanks the EU for Horizon 2020 Marie Skłodowska-Curie Fellowship (grant no. 794119, Fe-RedOx-Cat)

Role of geographical provenance in the response of silver fir seedlings to experimental warming and drought

Changes in climate can alter the distribution and population dynamics of tree species by altering their recruitment patterns, especially at range edges. However, geographical patterns of genetic diversity could buffer the negative consequences of changing climate at rear range edges where populations might also harbour individuals with drought-adapted genotypes. Silver fir (Abies alba) reaches its south-western distribution limit in the Spanish Pyrenees, where recent climatic dieback events have disproportionately affected westernmost populations. We hypothesised that silver fir populations from the eastern Pyrenees are less vulnerable to the expected changing climate due to the inclusion of drought-resistant genotypes. We performed an experiment under strictly-controlled conditions simulating projected warming and drought compared with current conditions and analysed physiology, growth and survival of silver fir seedlings collected from eastern and western Pyrenean populations. Genetic analyses separated eastern and western provenances in two different lineages. Climate treatments affected seedling morphology and survival of both lineages in an overall similar way: elevated drought diminished survival and induced a higher biomass allocation to roots. Increased temperature and drought provoked more negative stem water potentials and increased δ13C ratios in leaves. Warming reduced nitrogen concentration and increased soluble sugar content in leaves, whereas drought increased nitrogen concentration. Lineage affected these physiological parameters, with western seedlings being more sensitive to warming and drought increase in terms of δ13C, nitrogen and content of soluble sugars. Our results demonstrate that, in Abies alba, differences in the physiological response of this species to drought are also associated with differences in biogeographical history

Estructura sanitaria de atención al tabaquismo

El presente artículo trata de analizar la necesidad de generar una estructura sanitaria de atención al tabaquismo en los distintos departamentos de salud, dependientes de la red pública sanitaria. Esta estructura cobra fuerza y llega a un mayor número de sujetos si se asienta sobre la Atención Primaria de salud, articulándose alrededor de las consultas específicas de tabaquismo en los distintos centros de Salud. Estas consultas deben contar como mínimo con un médico y una enfermera que se dediquen especialmente a atender la consulta al menos 4 horas a la semana. Aun siendo la Atención Primaria la principal puerta de entrada de los pacientes, no podemos descartar el papel de otras unidades o servicios como, medicina Preventiva, los servicios de Neumología o las Unidades de Conductas Adictivas, que también deben hacer un papel importante a la hora de su interrelación. Con todo esto hay que establecer una correcta coordinación entre los distintos servicios, consultas y unidades, sumando a ellas los recursos de Salud Pública e incluso el apoyo que se pueda ofrecer desde distintos ayuntamientos y otras administraciones no sanitarias. Al contar con una estructura definida y una organización coordinada se puede llegar al máximo número de pacientes, además de realizar otras tareas como la prevención o incluso la investigación en este campo, por parte de personas que conozcan toda la problemática de los fumadores. A pesar de los documentos previos, llega la hora de que los distintos gobiernos tanto a nivel autonómico como estatal, consensúen y establezcan un modelo de Atención sanitaria al tabaquismo para todo el Estado español. En este trabajo, aparte de presentar nuestro proyecto, ofrecemos los resultados preliminares que nos indica que nuestra experiencia es efectiva y eficiente en nuestro Departamento de Salud cuando se compara con otros trabajos. Esperamos que con el seguimiento aportemos datos más concluyentes

Oxidant-Free Au(I)-Catalyzed Halide Exchange and Csp2–O Bond Forming Reactions

Au has been demonstrated to mediate a number of organic transformations through the utilization of its π Lewis acid character, Au(I)/Au(III) redox properties or a combination of both. As a result of the high oxidation potential of the Au(I)/Au(III) couple, redox catalysis involving Au typically requires the use of a strong external oxidant. This study demonstrates unusual external oxidant-free Au(I)-catalyzed halide exchange (including fluorination) and Csp2–O bond formation reactions utilizing a model aryl halide macrocyclic substrate. Additionally, the halide exchange and Csp2–O coupling reactivity could also be extrapolated to substrates bearing a single chelating group, providing further insight into the reaction mechanism. This work provides the first examples of external oxidant-free Au(I)-catalyzed carbon–heteroatom cross-coupling reactions

¿Cómo influye la riqueza genética de los abetos pirenaicos en su respuesta al cambio climático?

Noticia publicada por la Agencia Sinc: El Servicio de Información y Noticias Científicas (SINC) es la primera agencia pública de ámbito estatal especializada en información sobre ciencia, tecnología e innovación en español. En la página web de iAguaUn estudio demuestra que los abetares más antiguos son más tolerantes a condiciones de aumento de temperatura y disminución de precipitación. El mantenimiento de la diversidad ayuda a los expertos a contar con individuos adaptados, idóneos en las restauraciones, que eviten el decaimiento de la especie.N

Genes y edad de los abetos pirenaicos, claves en su respuesta al cambio climático

Noticial en el Blog de la Web Fundación Descubre: Fundación Andaluza para la Divulgación de la Innovación y el ConocimientoUn estudio demuestra que los abetares más antiguos son más tolerantes a condiciones de aumento de temperatura y disminución de precipitación. El mantenimiento de la diversidad ayuda a los expertos a contar con individuos adaptados, idóneos en las restauraciones, que eviten el decaimiento de la especie.Peer reviewe

Enantio- and diastereocontrol in intermolecular cyclopropanation reaction of styrene catalyzed by dirhodium(II) complexes with bulky ortho-metalated aryl phosphines

Enantiomerically pure dirhodium(II) complexes with ortho-metalated p-substituted aryl phosphines have been shown to be enantio- and diastereoselective in the cyclopropanation of styrene by ethyl diazoacetate. Enantioselectivities up to 91% and diastereoselectivities up to 90% are observed for ethyl cis-2-phenylcyclopropanecarboxylate.Estevan Estevan, Francisco, [email protected] ; Lahuerta Peña, Pascual, [email protected] ; Lloret Fillol, Julio, [email protected] ; Sanau Torrecilla, Mercedes, [email protected] ; Ubeda Picot, M Angeles, [email protected] ; Vila Gomez, Jaume Llorenc, [email protected]

Auxin Modulated Initiation of Lateral Roots Is Linked to Pericycle Cell Length in Maize

Auxin is essential for the regulation of root system architecture by controlling primary root elongation and lateral root (LR) formation. Exogenous auxin has been reported to inhibit primary root elongation and promote the formation of LRs. In this study, LR formation in the Zea mays primary root was quantitatively evaluated after exogenous auxin treatment by comparing the effects of auxin on two selected zones elongated either before or after auxin application. We determined two main variables in both zones: the LR density per unit of root length (LRD), and the mean phloem pericycle cell length. The total number of phloem pericycle cells (PPCs) per unit of root length was then calculated. Considering that each LR primordium is initiated from four founder cells (FCs), the percentage of PPCs (%PPC) that behave as FCs in a specific root zone was estimated by dividing the number of pericycle cells by four times the LRD. This index was utilized to describe LR initiation. Root zones elongated in the presence of a synthetic auxin (1-naphthalene acetic acid, NAA) at low concentrations (0.01 μM) showed reduced cell length and increased LRD. However, a high concentration of NAA (0.1 μM) strongly reduced both cell length and LRD. In contrast, both low and high levels of NAA stimulated LRD in zones elongated before auxin application. Analysis of the percentage of FCs in the phloem pericycle in zones elongated in the presence or absence of NAA showed that low concentrations of NAA increased the %PFC, indicating that LR initiation is promoted at new sites; however, high concentrations of NAA elicited a considerable reduction in this variable in zones developed in the presence of auxin. As these zones are composed of short pericycle cells, we propose that short pericycle cells are incapable to participate in LR primordium initiation and that auxin modulated initiation of LRs is linked to pericycle cell length

The synergy between the CsPbBr 3 nanoparticle surface and the organic ligand becomes manifest in a demanding carbon–carbon coupling reaction

We demonstrate here the suitability of CsPbBr3nanoparticles as photosensitizers for a demanding photoredox catalytic homo- and cross-coupling of alkyl bromides at room temperature by merely using visible light and an electron donor, thanks to the cooperative action between the nanoparticle surface and organic capping.Fil: Rosa-Pardo, Ignacio. Instituto de Ciencia Molecular; España. Universidad de Valencia; EspañaFil: Casadevall, Carla. Barcelona Institute Of Science And Technology. Institut Català D'investigació Química.; EspañaFil: Schmidt, Luciana Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Castro Claros, José Miguel. Barcelona Institute Of Science And Technology. Institut Català D'investigació Química.; EspañaFil: Galian Baca, Raquel Eugenia. Instituto de Ciencia Molecular; España. Universidad de Valencia; EspañaFil: Lloret-Fillol, Julio. Barcelona Institute Of Science And Technology. Institut Català D'investigació Química.; EspañaFil: Pérez-Prieto, Julia. Instituto de Ciencia Molecular; España. Universidad de Valencia; Españ

Generation, Spectroscopic, and Chemical Characterization of an Octahedral Iron(V)-Nitrido Species with a Neutral Ligand Platform

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