56 research outputs found
Multichromophores Onto Graphene: Supramolecular Non-Covalent Approaches for Efficient Light Harvesting.
No full textThe idea of attaching multiple porphyrins to graphene is explored. A charged porphyrin salt is stabilized onto exfoliated graphene by taking advantage of π-π* interactions and a second porphyrin light harvester is anchored through electrostatic interactions with the former. The interactions are capable of allowing electronic communication of the second, electrostatically attached, porphyrin with graphene, effectively quenching its emission. The graphene-porphyrin-porphyrin triad is examined through optical (UV-Vis, steady state and time resolved photoluminescence) techniques, while electrochemistry is employed to study the thermodynamically favored pathways through which the interaction occurs. The porphyrin that is electrostatically stabilized onto the graphene nanoensemble shows lifetimes one order of magnitude faster than its π-π* stacked analogue suggesting a more efficient pathwa
Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)
No full textThe electrochemical oxidation of polycyclic aromatic phenols (PAPs) has been developed in a microfluidic cell to synthesize polycyclic aromatic quinones (PAQs). Methanol was used as nucleophile to trap the phenoxonium cation formed in the oxidation as an acetal, that later were hydrolysed to the quinone. Formation of hydrogen gas as the cathode reaction caused challenges in the flow cell and were overcome by recycling the reaction mixture through the cell at increased flow rate several times. The specific quinones formed were guided by the position of an initial hydroxy group on the polycyclic aromatic hydrocarbon. An available para-position in the PAPs gave p-quinones, while hydroxy groups in the 2- or 3-position led to o-quinones. The substrates were analysed by cyclic voltammetry for estitmation of the HOMO/LUMO energies to shed more light on this transformation. The easy separation of the supporting electrolyte from the product will allow recycling and makes this a green transformation
Correspondence
No full textAuthor complains that former business partners/landlords should return his deposit because his failure to meet the contract terms was the result of their failure
Uncertainty and the Disappearance of International Credit
No full textWe show that increased uncertainty about the size of an emerging market's external debt has a nonlinear and potentially large adverse effect on the supply of international credit offered to them. We also show that if international creditors are first- order risk averse, attaching greater weight to utility derived from bad outcomes than from good ones, a moderate increase in uncertainty about debt overhang or about other relevant factors affecting repayment prospects-- can cause the supply of credit to dry up completely. We therefore offer one possible explanation for why emerging markets may find themselves suddenly cut off from international capital markets.
2006 Author Recognition Bibliography
No full texthttps://scholarworks.gvsu.edu/authorrecognition/1008/thumbnail.jp
Effect of π-linkers on phenothiazine sensitizers for dye-sensitized solar cells
No full textEleven new dyes have been synthesized in order to investigate the effect of five different π-spacers and two different auxiliary donors in phenothiazine-based sensitizers for dye-sensitized solar cells. The target molecules were synthesized in 5–7 steps from 10H-phenothiazine. Evaluation of the photovoltaic performance revealed that introducing a π-spacer does not necessarily increase the power conversion efficiency. Still, dyes with a furan π-spacer were found to be slightly more efficient compared to their thiophene counterparts, and more efficient than no spacer. Dyes with phenyl based π-spacers resulted in less efficient solar cells, and especially so when incorporating two fluorine atoms. Surprisingly, introducing an additional electron donating group in the auxiliary donor had no pronounced effect on the photovoltaic performance of the dyes.acceptedVersion© 2018. This is the authors’ accepted and refereed manuscript to the article. Locked until 9.1.2020 due to copyright restrictions. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.
Exfoliation and Chemical Modification Using Microwave Irradiation Affording Highly Functionalized Graphene
No full textNew hybrid materials with porphyrin-ferrocene and porphyrin-pyrene covalently linked to single-walled carbon nanotubes.
No full textNovel porphyrin derivatives bearing additional pyrene or ferrocene units as light harvesting antenna systems were synthesized and fully characterized. Following a covalent functionalization approach for single-walled carbon nanotubes (SWCNTs), stable SWCNT suspensions in common organic solvents 10 were produced. Subsequently, the resulting porphyrin-pyrene and porphyrin-ferrocene dyads were incorporated onto the nanotubes' backbone yielding donor-donor-acceptor hybrids. The resulting hybrid materials were soluble in common organic solvents and were characterized using micro-Raman, ATR-IR,
UV-Vis and photoluminescence spectroscopy, transmission electron microscopy, thermogravimetric analysis and εlectrochemistry. Photoluminescence quenching of the porphyrin emission in both hybrid 15 materials was detected thus suggesting the potentiality of these materials in photoelectrochemical cells
Restauración de un arma de la sala del Mundo Árabe del MNC. La pistola ametralladora FNAB PM43 CAL 9mm, una breve historia. 61 Tercera época (2015) abril-julio. Gaceta de Museos. Museo Nacional de las Culturas. 50 años
No full textAlfonso, B. A., “Antagonistas”, 2007, en línea [http://antagonistas.blogia.com/2007/033001-estado-partido-pueblo-revolucion.php], consultado el 27 de septiembre de 2001.Castañeda Reyes, José Carlos, “Carta resumen del proceso de inauguración de la sala del Mundo Árabe del mnc”, 6 de julio de 1989.Castellanos, A., R. Ruiz y D. Vega, “Fusil de asalto ak-47”, en Informe de intervenciones realizadas a 3 piezas procedentes del Museo Nacional de las Culturas, México, Seminario Taller de Restauración de Metales-encrym-inah-sep, 2012 [inédito].Ferrari, P. A., “Universidad de San Andrés (UBA/UDESA)”, 2009,en línea [https://ude-sa.edu.ar/files/UAHumanidades/DT/DT47-AnaFerrari.pdf], consultado el 8 de octubre de 2012.Gómez, A., “Representar a una cultura: el caso de la sala del Mundo árabe del Mu-seo Nacional de las Culturas”, tesis de licenciatura en antropología social,México, ENAH-INAH, 1998.Hogg, I. V., The Complete Illustrated Encyclopedia of the World’s Firearms,Nueva York, A-W, 1978.J. M., M., “Miniaturas JM”, 2009, en línea [http://www.miniaturasjm.com/uniformo-logia/uniformes-italianos-ejercito-italiano-en-italia-19401943/], consultado el 5 de octubre de 2012.Molina Tijeras, Pedro, La Segunda Guerra Mundial en sus citas, España, Pedro Molina, 2008.Müller Solon, Hugo, “Policía comunitaria. Nuevo paradigma del siglo XXI”, Seguridad Ahora, ¿dí...?, noviembre de 2003.Vergara J., R.J.D.M., “Universidad de Tarapacá. Arica, Chile”, 2007,en línea [http://congreso.pucp.edu.pe/cibim8/pdf/15/15-90.pdf], consultado el 10 de octubre de 2012
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