Mostrando recursos 1 - 20 de 2.045

  1. Oficina temática de cosméticos para o ensino de química orgânica : observação da permanência dos alunos em sala de aula em um período instável pós-greves e ocupações

    Oliveira, Aline Grance de
    O presente trabalho objetiva apresentar uma abordagem contextualizada dos conteúdos de química orgânica através de oficina temática com o intuito de contribuir para motivar os alunos e incentivá-los a participar ativamente das aulas, aumentar a taxa de presença e retê-los na escola. O trabalho foi aplicado em uma escola pública estadual em uma turma noturna onde a preocupação dos professores com esses alunos era muito grande. Utilizou-se uma metodologia de pesquisa qualitativa do tipo Investigação-Ação. Os instrumentos utilizados nesta pesquisa foram o diário de campo da autora e os trabalhos desenvolvidos ao longo do período de duração da oficina pelos...

  2. Evaluación continua y análisis de resultados en las asignaturas del grado de química impartidas por el departamento de química orgánica

    Alonso Velasco, Diego A.; Alonso Valdés, Francisco; Baeza Carratalá, Alejandro; Chinchilla Cruz, Rafael; Foubelo García, Francisco; Gómez Lucas, Cecilia; Guijarro Espí, David; Guillena, Gabriela; Maciá Ruiz, Beatriz; Sansano, Jose M.; Ramón Dangla, Diego J.; González Gómez, José Carlos; Guijarro Pastor, Albert; Pastor Beviá, Isidro M.
    En esta comunicación se pondrán en común las experiencias de distintos docentes del Departamento que han impartido asignaturas de Química Orgánica tanto en la antigua Licenciatura como en el nuevo Grado de Químicas. Las asignaturas en que se focaliza el estudio, debido a que son de obligada realización, son: Química Orgánica, Estereoquímica Orgánica, Determinación Estructural de Compuestos Orgánicos y Química Orgánica Avanzada. El objetivo de este estudio permitirá evaluar los cambios que se han llevado a cabo desde el punto de vista de las nuevas metodologías docentes que se han debido aplicar así como de los cambios de contenido que han sufrido las asignaturas. También se...

  3. Diseño y desarrollo de un sistema electroquímico para la eliminación de fenol de aguas residuales mediante oxidación anódica

    Espinosa Gómez, Andrea
    La Unión Europea establece en la Directiva marco de actuación (Directiva 2000/60/CE del Parlamento Europeo y del Consejo), en el ámbito de la política del agua, la siguiente definición referente a ésta “no es un bien comercial como los demás, sino un patrimonio que hay que conservar, defender y tratar como tal”. La industria consume entre un 5 y un 20% del agua total consumida por la humanidad, y a su vez genera una significativa parte de la contaminación de las aguas. Los efluentes procedentes de las diversas industrias contienen, cada vez en mayor medida, contaminantes más persistentes en concentraciones mucho...

  4. Anti-site disorder and physical properties in microwave synthesized RE2Ti2O7 (RE = Gd, Ho) pyrochlores [Recurso electrónico] / A. Gómez-Pérez ... [et al.].

    Amador, Ulises, coaut.; Gómez Pérez, Alejandro, coaut.
    Artículo en colaboración con: Jesús Prado-Gonjal, Daniel Muñoz-Gil, Adrián Andrada-Chacón, Javier Sánchez-Benítez, Emilio Morán, M? Teresa Azcondo, Ulises Amador, Rainer Schmidt

  5. Journal of Materials Chemistry C Q123 top picks web collection: the many faces of carbon

    Martín, Nazario
    Nazario Martı´n introduces this Journal of Materials Chemistry C top picks web collection on the many faces of carbon.

  6. Graphene Nanoribbons Via Crystal Engineering

    Evans, Paul J.; Martín, Nazario
    In this issue of Chem, Rubin and coworkers have developed a new approach for the bottom-up synthesis of graphene nanoribbons by efficiently combining crystal engineering and topochemical polymerization.

  7. Subphthalocyanine-based systems focused on molecular photovoltaics

    Zango Casado, Germán
    Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Orgánica. Fecha de lectura: 15-12-2016

  8. Nanoforms for Photovoltaics: Myth or Reality?

    Martín, Nazario

  9. Photochemical site-selective synthesis of [70]methanofullerenes

    Vidal, Sara; Izquierdo, Marta; Kit Law, Wai; Jiang, Kui; Filippone, Salvatore; Perles, Josefina; Yan, He; Martín, Nazario
    Methanofullerenes such as the well-known [70]PCBM are commonly synthesized under harsh conditions to obtain the product as a mixture of site-isomers (namely a, b and minor c) due to the D5h symmetry of the C70 cage. We report the first site-selective synthesis of [70]methanofullerenes under light irradiation and low temperatures, thus avoiding time-consuming and highly expensive HPLC separations. Pure major site-isomers a-[70]PCBM and a-[70]DPM have been thus efficiently prepared including the crystal structure of 5b. Photovoltaic preliminary results revealed a slightly beneficial performance for a-pure [70]PCBM site-isomer devices.

  10. The mechanical bond on carbon nanotubes: diameter-selective functionalization and effects on physical properties

    Martínez Periñan, Emiliano; Juan, Alberto de; Pouillon, Yann; Schierl, Christoph; Strauss, Volker; Martin, Nazario; Rubio, Angel; Guldi, Dirk M.; Lorenzo, Encarnación; Pérez, Emilio M.
    We describe the functionalization of SWNTs enriched in (6,5) chirality with electron donating macrocycles to yield rotaxane-type mechanically interlocked carbon nanotubes (MINTs).Investigations by means of TEM and control experiments corroborated the interlocked nature of the MINTs. A comprehensive characterization of the MINTs through UV-vis-NIR, Raman, fluorescence, transient absorption spectroscopy, cyclic voltammetry, and chronoamperometry was carried out.Analyses of the spectroscopic data reveal that the MINT-forming reaction proceeds with diameter selectivity, favoring functionalization of (6,5) SWNTs rather than larger (7,6) SWNTs. In the ground state, we found a lack of significant charge-transfer interactions between the electron donor exTTF and the SWNTs. Upon...

  11. Cyclooctyne [60]fullerene hexakis adducts: a globular scaffold for copper-free click chemistry

    Ramos, Soriano; Reina, José J.; Pérez, Sánchez; Illescas, Beatriz M.; Rojo, Javier; Martín, Nazario
    The synthesis of a new highly symmetric hexakis adduct of C60 appended with 12 cyclooctyne moieties has been carried out. This compound has been used for the copper-free strain-promoted cycloaddition reaction to a series of azides with excellent yields.This strategy for the obtention of clicked adducts of [60]fullerene is of special interest for biological applications.

  12. Repeat protein scaffolds: ordering photo- and electroactive molecules in solution and solid state

    Mejías, Sara H.; López Andarias, Javier; Sakurai, Tsuneaki; Yoneda, Satoru; Erazo, Kevin P.; Seki, Shu; Atienza, Carmena; Martín, Nazario; Cortajarena, Aitziber L.
    The precise control over the organization of photoactive components at the nanoscale is one of the main challenges for the generation of new and sophisticated macroscopically ordered materials with enhanced properties. In this work we present a novel bioinspired approach using protein-based building blocks for the arrangement of photo and electroactive porphyrin derivatives. We used a designed repeat protein scaffold with demonstrated unique features that allow for the control of their structure, functionality, and assembly. Our designed domains act as exact biomolecular templates to organize porphyrin molecules at the required distance. The hybrid conjugates retain the structure and assembly properties of...

  13. Stereodivergent-at-Metal Synthesis of [60]Fullerene Hybrids

    Marco Martínez, Juan; Vidal, Sara; Fernández, Israel; Filippone, Salvatore; Martín, Nazario
    Chiral fullerene–metal hybrids with complete control over the four stereogenic centers, including the absolute configuration of the metal atom, have been synthesized for the first time. The stereochemistry of the four chiral centers formed during [60]fullerene functionalization is the result of both the chiral catalysts employed and the diastereoselective addition of the metal complexes used (iridium, rhodium, or ruthenium).DFT calculations underpin the observed configurational stability at the metal center, which does not undergo an epimerization process.

  14. Cyclobuteno[60]fullerenes as efficient n-type organic semiconductors

    Reboredo, Silvia; Girón, Rosa M.; Filippone, Salvatore; Mikie, Tsubasa; Sakurai, Tsuneaki; Seki, Shu; Martín, Nazario
    Cyclobuteno[3,4:1,2][60]fullerenes have been prepared in a straightforward manner by a simple reaction between [60]fullerene and readily available allenoates or alkynoates as organic reagents under basic and mild conditions. The chemical structure of the new modified fullerenes has been determined by standard spectroscopic techniques and confirmed by X-Ray diffraction analysis. Some of these new fullerene derivatives exhibit a remarkable intrinsic electron mobility – determined by using flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements – which surpasses that of the well-known PCBM, thus behavi ng as promising n-type organic semiconductors.

  15. Conjugated Porphyrin Dimers: Cooperative Effects and Electronic Communication in Supramolecular Ensembles with C60

    Moreira, Luis; Calbo, Joaquín; Aragó, Juan; Illescas, Beatriz M.; Nierengarten, Iwona; Delavaux-Nicot, Béatrice; Ortí, Enrique; Martín, Nazario; Nierengarten, Jean-Françoise
    Two new conjugated porphyrin-based systems (dimers 3 and 4) endowed with suitable crown ethers have been synthesized as receptors for a fullerene-ammonium salt derivative (1). Association constants in solution have been determined by UVvis titration experiments in CH2Cl2 at room temperature. The designed hosts are able to associate up to two fullerene-based guest molecules and present association constants as high as 5 × 108 M‒1 . Calculation of the allosteric cooperative factor  for supramolecular complexes [3·12] and [4·12] showed a negative cooperative effect in both cases. The interactions accounting for the formation of the associates are based, firstly, on the...

  16. Analysis of the Hysteresis Behavior of Perovskite Solar Cells with Interfacial Fullerene Self-Assembled Monolayers

    Valles Pelarda, Marta; Clasen Hames, Bruno; García Benito, Inés; Almora, Osbel; Molina Ontoria, Agustín; Sánchez, Rafael S.; García Belmonte, Germà; Martín, Nazario; Mora Sero, Iván
    The use of self-assembled monolayers (SAMs) of fullerene derivatives reduces the hysteresis of perovskite solar cells (PSCs). We have investigated three different fullerene derivatives observing a decrease on hysteresis for all the cases. Several processes can contribute to the hysteresis behavior on PSCs. We have determined that the reduced hysteresis observed for devices with SAMs is produced by a decrease of the capacitive hysteresis. In addition, with an appropriated functionalization, SAMs can increase photocurrent even when no electron selective contact (ESC) is present and a SAM is deposited just on top of the transparent conductive oxide. Appropriated functionalization of the...

  17. Supramolecular Complexation of Carbon Nanostructures by Crown Ethers

    Moreira, Luis; Illescas Martínez, Beatriz M.; Martín, Nazario
    Since their discovery, crown ethers as well as the most recent carbon nanostructures, namely fullerenes, carbon nanotubes, and graphene, have received a lot of attention from the chemical community. Merging these singular chemical structures by noncovalent forces has provided a large number of unprecedented supramolecular assemblies with new geometric and electronic properties whose more representative examples are presented in this Synopsis organized according to the different nature of the carbon nanostructures.

  18. Synthesis and Optoelectronic Properties of Chemically Modified Bifluorenylidenes.

    Wielopolski, Mateusz; Marszalek, Magdalena; Brunetti, Fulvio G.; Joly, Damien; Calbo, Joaquín; Aragó, Juan; Moser, Jacques-E.; Humphry-Baker, Robin; Zakeeruddin, Shaik M.; Delgado, Juan Luis; Grätzel, Michael; Ortí, Enrique; Martin, Nazario

  19. Collective Concerted Motion in a Molecular Adlayer Visualized through the Surface Diffusion of Isolated Vacancies

    Urban, Christian; Otero, Roberto; Ecija, David; Trelka, Marta; Martín, Nazario; Gallego, José María; Miranda, Rodolfo
    We have measured STM movies to study the diffusion of individual vacancies in a self-assembled layer of a tetrathiafulvalene derivative (exTTF) on Au(111) at room temperature. The diffusion is anisotropic, being faster along the compact direction of the molecular lattice. A detailed analysis of the anisotropic displacement distribution of the single vacancies shows that the relative abundance of double jumps (that is, the collective motion of molecular dimers) with respect to single jumps is rather large, the number of double jumps being more than 20% of the diffusion events. We conjecture that the relative abundances of long jumps might be...

  20. Synthesis of modified fullerenes for oxygen reduction reactions

    Girón, Rosa María; Martínez, Juan Marco; Bellani, Sabastiano; Insuasty, Alberto; Comas Rojas, Hansel; Antognazza, María Rosa; Filippone, Salvatore; Martín, Nazario
    In the search for carbon based catalysts for Oxygen Reduction Reactions (ORR), two different classes of fullerene hybrids and metal free fullerene derivatives have been prepared by highly selective metal- and organo-catalyzed synthetic methods. They were included as both electron acceptors and catalysts in polymer-based photo-electrochemical cell,fully demonstrating electrocatalytic activity. Remarkably, the activity of the metal free fullerenes proved to be as high as that observed for metallofullerenes based on noble metals, and up to ten-fold higher than by using PCBM.

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.