Radical Fluoroalkylation Reactions

Recent protocols and reactions for catalytic radical perfluoroalkylations will be described. The production of perfluoroalkyl radicals (RF = CnF2n+1, n ≥ 2), which effect both addition and substitution reactions on organic substrates, can be realized through a range of diverse methods such as the well-established visible-light transition-metal-mediated photocatalysis, organic-dye-photocatalyzed reactions, electron donor-acceptor complexes, and more recently frustrated Lewis pairs. Thus, perfluoroalkylation reactions of carbon-carbon multiple bonds, isocyanides, nitrones, hydrazones, β-keto esters, α-cyano arylacetates, sulfides, and (hetero)arenes will be described. Special emphasis will be placed on examples published after 2015, where higher fluorinated series of fluoroalkylating reagents are studied.Fil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cooke, María Victoria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Postigo, A.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentin

Polarización en el consumo de (ciertos) bienes de lujo en el Ecuador

The present work seeks to find the theoretical possibility that in Ecuador there are certain luxury goods whose demand presents a curve of Engel in the form of S. First, a theoretical model is proposed where utility depends on two functionalities and also on an added factor, the level of status...El presente trabajo de titulaci´on busca encontrar la posibilidad te´orica de que en el Ecuador existan ciertos bienes de lujo cuya demanda presenta una curva de Engel en forma de S. Primero, se plantea un modelo te´orico donde la utilidad depende de dos funcionalidades y tambi´en de un factor agregado, el nivel de estatus..

Bleomycin-induced trans lipid formation in cell membranes and in liposome models

Cell cultures of NTera-2 cells incubated with bleomycin and liposomes as biomimetic models of cell membranes were used for examining some novel aspects of drug-metal induced reactivity with unsaturated lipids under oxidative conditions. In cell cultures, bleomycin was found for the first time to cause the formation of trans fatty acids. The chemical basis of this transformation was ascertained by liposome experiments, using bleomycin-iron complexes in the presence of thiol as a reducing agent that by incubation at 37 °C gave rise to the thiyl radical-catalysed double bond isomerisation of membrane phospholipids. The effect of oxygen and reagent concentrations on the reaction outcome was studied. An interesting scenario of free radical reactivity is proposed, which can be relevant for understanding the role of membrane lipids in antitumoral treatments and drug carrier interaction.Fil: Cort, Aysegul. Akdeniz University. Faculty of Medicine; Turquía. Consiglio Nazionale delle Ricerche; ItaliaFil: Ozben, Tomris. Akdeniz University. Faculty of Medicine; TurquíaFil: Sansone, Anna. Consiglio Nazionale delle Ricerche; ItaliaFil: Barata Vallejo, Sebastian. Consiglio Nazionale delle Ricerche; Italia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chatgilialoglu, Chryssostomos. Demokritos National Centre For Scientific Research; GreciaFil: Ferreri, Carla. Consiglio Nazionale delle Ricerche; Itali

Photocatalytic Difluoromethylation Reactions of Aromatic Compounds and Aliphatic Multiple C-C Bonds

Among the realm of visible light photocatalytic transformations, late-stagedifluoromethylation reactions (introduction of difluoromethyl groups in the last stages of syntheticprotocols) have played relevant roles as the CF2X group substitutions exert positive impacts on thephysical properties of organic compounds including solubility, metabolic stability, andlipophilicity, which are tenets of considerable importance in pharmaceutical, agrochemical, andmaterials science. Visible-light-photocatalyzed difluoromethylation reactions are shown to beaccomplished on (hetero)aromatic and carbon?carbon unsaturated aliphatic substrates under mildand environmentally benign conditions.Fil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin

Combined Raman and IR spectroscopic study on the radical-based modifications of methionine

Among damages reported to occur on proteins, radical-based changes of methionine (Met) residues are one of the most important convalent post-translational modifications. The combined application of Raman and infrared (IR) spectroscopies for the characterisation of the radical-induced modifications of Met is described here. Gamma-irradiation was used to simulate the endogenous formation of reactive species such as hydrogen atoms ( •H), hydroxyl radicals ( •OH) and hydrogen peroxide (H 2O 2). These spectroscopic techniques coupled to mass experiments are suitable tools in detecting almost all the main radical-induced degradation products of Met that depend on the nature of the reactive species. In particular, Raman spectroscopy is useful in revealing the radical-induced modifications in the sulphur-containing moiety, whereas the IR spectra allow decarboxylation and deamination processes to be detected, as well as the formation of other degradation products. Thus, some band patterns useful for building a library of spectra-structure correlation for radical-based degradation of Met were identified. In particular, the bands due to the formation of methionine sulfoxide, the main oxidation product of Met, have been identified. All together, these results combine to produce a set of spectroscopic markers of the main processes occurring as a consequence of radical stress exposure, which can be used in a spectroscopic protocol for providing a first assessment of Met modifications in more complex systems such as peptides and proteins, and monitoring their impact on protein structure.Fil: Torreggiani, A.. Consiglio Nazionale delle Ricerche; ItaliaFil: Barata Vallejo, Sebastian. Consiglio Nazionale delle Ricerche; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Chatgilialoglu, C.. Consiglio Nazionale delle Ricerche; Itali

Depolarization of echo chambers by random dynamical nudge

Interactions among individuals in social networks lead to echo chambers where the distribution of opinions follows a bimodal distribution with two peaks at the opposite extremes. In issues with clear answers, such as global warming, one of the echo chambers reflects an inaccurate judgment, potentially from misinformation. However, in issues without clear answers such as elections, the neutral consensus is preferable for promoting discourse. In this letter, we use an opinion dynamics model to study the effect of a random dynamical nudge where we present random input to each agent from the other individuals in the network. We show that random dynamical nudge disallows the formation of echo chambers and leads to a normal distribution of opinions centered around the neutral consensus. The random dynamical nudge relies on the collective dynamics and it does not require surveillance of every person's opinions. Social media networks could implement a version of this self-feedback mechanism to prevent the formation of segregated online communities on pressing issues such as elections.Comment: 9 pages, 4 Fig

Tres ejemplos de inversión causal en el discurso psicoanalítico (1896-1913): Sigmund Freud, Karl Abraham y Ernest Jones.

ResumenLo que sigue contiene algunas reflexiones sobre la temprana construcción del discurso psicoanalítico. Son reflexiones que, sin pretenderse estrictamente filosóficas, giran en torno a la demarcación de la operatoria de tres inversiones causales en la problematización freudiana de una serie de tópicos estrechamente ligados entre sí. Estas páginas resultan de una investigación que, teniendo como telón de fondo una indagación acerca del problema de la herencia de las enfermedades en la medicina y la ciencia social del siglo XIX, busca precisar qué perspectiva sobre la determinación hereditaria y familiar el psicoanálisis hizo suya desde sus albores.AbstractThe following contains some reflections on the early construction of psychoanalytic discourse. They are reflections that, although not strictly philosophical, revolve around the demarcation of the operation of three causal investments in the Freudian consideration of a series of closely intertwined topics. These pages are the result of an investigation which, on the background of an inquiry into the problem of disease inheritance in 19th century medicine and social science, intends to clarify what perspective on the determination by inheritance and by family was used by psychoanalysis from its infancy.

Photocatalytic fluoroalkylation reactions of organic compounds

Photocatalytic methods for fluoroalkyl-radical generation provide more convenient alternatives to the classical perfluoroalkyl-radical (Rf) production through chemical initiators, such as azo or peroxide compounds or the employment of transition metals through a thermal electron transfer (ET) initiation process. The mild photocatalytic reaction conditions tolerate a variety of functional groups and, thus, are handy to the late-stage modification of bioactive molecules. Transition metal-photocatalytic reactions for Rf radical generation profit from the redox properties of coordinatively saturated Ru or Ir organocomplexes to act as both electron donor and reductive species, thus allowing for the utilization of electron accepting and donating fluoroalkylating agents for Rf radical production. On the other hand, laboratory-available and inexpensive photoorgano catalysts (POC), in the absence of transition metals, can also act as electron exchange species upon excitation, resulting in ET reactions that produce Rf radicals. In this work, a critical account of transition metal and transition metal-free Rf radical production will be described with photoorgano catalysts, studying classical examples and the most recent investigations in the field.Fil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bonesi, Sergio Mauricio. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Synthetic strategies for fluorosulfonylated compounds: application to click chemistry reactions

The syntheses and applications of fluorosulfonylated organic compounds have flourished in the last ten years due to their versatility to participate in click chemistry (SuFEx) reactions. Also, organic architectures that combine the SO2F group and other ancillary functional moieties such as olefins, alkynes, etc. (i.e.: bis-electrophiles) have augmented the applications and diversity of the end compounds. To this effect, the association of an alkyne functionality and the SuFExable group within one structure has been shown to encompass two-in-one click chemistry sequential protocols with the aim of building on the diversity of scaffolds by two consecutive click processes. We next examine the syntheses of (hetero)aromatic-, alkyl-, alkenyl-, and alkynyl-sulfonyl fluorides and β-keto-sulfonyl fluorides and the syntheses of compounds bearing N-SO2F and O-SO2F bonds through diverse catalytic methods, illustrating examples of their SuFEx click chemistry and other ancillary functional group reactivity.Fil: Barata Vallejo, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; Argentina. Consiglio Nazionale delle Ricerche. Istituto per la Sintesi Organica e la Fotoreattività; ItaliaFil: Yerien, Damián Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; ArgentinaFil: Postigo, Jose Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; Argentin

Dry friction and wear of self-lubricating carbon-nanotube-containing surfaces

The unfavorable environmental conditions of certain tribological systems, such as operation at high temperatures or under vacuum, set the need to replace liquid with solid lubricants. Multi-Wall-Carbon Nanotubes (MWCNTs) have been emphasized as a very effective solid lubricant. The particles have been used to create self-lubricating materials by acting as reinforcement phase in composites or as solid-lubricant coating that works in conjunction with textured surfaces to prevent the removal of particles from the contact. However, both approaches are restricted to some extent. In the case of composites, the solid lubricant concentration is limited so as not to influence the mechanical stability of the final component. For coated surface structures, the textured surfaces can degrade during the experiment. The present study focuses on the combination of these approaches in order to create enhanced self-lubricating surfaces with MWCNTs as the solid lubricant. A custom-made ring-on-block tribometer is used to study the behavior of laser textured MWCNT-coated and MWCNT-reinforced nickel matrix composites under the conditions of unidirectional sliding in conformal contact. It is shown that the combination of both approaches allows for a maximum 4-fold reduction in friction and a 115-fold reduction in wear rate compared to the reference. Additionally, the lubrication mechanism of the MWCNTs is investigated in more detail and a structural degradation model of the mechanically stressed MWCNTs is proposed. Our results highlight the integrated solution as a suitable approach for self-lubricating surfaces subjected to unidirectional sliding