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Nanopartículas magnéticas metálicas recobertas com óxido de ferro: intensificação das propriedades magnéticas da nanopartícula e funcionalização para aplicação em biomedicina; Iron oxide-coated metal magnetic nanoparticles: improved magnetic properties and surface functionalization for biomedical applications

Beck Júnior, Watson
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/02/2011 PT
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A utilização de nanopartículas (NP) magnéticas em várias áreas da biomedicina e biotecnologia vem recebendo elevado destaque nos últimos anos, graças à versatilidade de aplicações tais como: reparo de tecidos, diagnósticos, imagens por ressonância magnética, tratamento contra o câncer, separação celular, transporte controlado de drogas, entre outras. Atualmente, as NP com potencialidade de aplicação em biomedicina baseiam-se principalmente em óxidos magnéticos de ferro, os quais apresentam comportamento superparamagnético a temperatura ambiente e baixa magnetização da ordem de 60 emu g-1. A utilização dos óxidos se baseia em duas razões principais: facilidade e versatilidade de modificação da superfície e funcionalização devido aos grupos hidroxila na superfície das NP e pela baixa toxicidade comparada às NP magnéticas metálicas. Biocompatibilidade e funcionalidade específica são obtidas geralmente pela incorporação de materiais paramagnéticas e/ou diamagnéticos na superfície das NP contribuindo para diminuir ainda mais o baixo valor de magnetização de saturação dos óxidos. Nesse contexto, é necessário o desenvolvimento de novos núcleos magnéticos com elevado valor de magnetização...

Funcionalização de grafite em condições de Friedel-Crafts; Graphite Functionalization in Friedel-Crafts conditions.

Sawazaki, David Tatsuo Atique
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/09/2013 PT
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Neste trabalho foi realizada a funcionalização de grafite sem prévio tratamento em condições de Fridel-Crafts. Considerando que a grafite não possui hidrogênio em sua estrutura, não se observa uma reação de substituição eletrofílica. Por outro lado, o trabalho mostra o papel da umidade presente no grafite na reação de funcionalização. Dessa forma, foi proposto um mecanismo para a reação com a participação da água adsorvida na grafite estabilizando o carbocátion formado. O grafite funcionalizado obtido na reação foi utilizado como material eletródico. Para a reação de funcionalização, quatro moléculas foram utilizadas: ácido ferrocenomonocarboxílico, cloreto de 4-nitrobenzoíla, cloreto de 3,5-dinitrobenzoíla e ácido 3,4-dinitrobenzóico. Para o estudo das condições ótimas da reação, utilizou-se diferentes potências de radiação no reator de micro-ondas, sendo que a extensão da funcionalização mostrou-se sensível à variação deste parâmetro. Para a caracterização dos materiais, utilizou-se voltametria cíclica e análise térmica (TG e DTA). Resultados de infravermelho e Ramam são apresentados no Apêndice A. Os resultados eletroquímicos mostraram que os materiais funcionalizados em maiores potências apresentaram maior corrente Faradaica...

Processamento e funcionalização de pontas para aplicações biológicas de microscopia de força atômica; Processing and functionalization of tips for biologial applications of atomic force microscopy

Alberto Luís Dario Moreau
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/11/2005 PT
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Este trabalho teve como objetivo implementar a técnica de espectroscopia de força no Microscópio de Força Atômica (AFM) existente no LPD/IFGW/UNICAMP e aplicá-la ao estudo de pontas e amostras funcionalizadas com tiol (mercaptoundecanoic acid). Em particular, foi necessária uma caracterização minuciosa da ponta de AFM, utilizando imagens de microscopia eletrônica. Avaliamos a metalização da ponta com Au (necessária para a funcionalização), o raio da extremidade da ponta e as formas de aproximação da mesma em relação à amostra. Um estudo da constante de mola da alavanca onde se localiza a ponta foi realizado para obtermos valores das forças absolutas medidas. As medidas de força foram realizadas em atmosfera de N2 para evitarmos forças capilares embora também tenhamos realizado algumas medidas em meio ambiente. Variamos a técnica utilizada para a metalização da ponta (sputtering e deposição térmica), a concentração da solução tiol/etanol e os tempos de funcionalização das pontas e amostras. As medidas de força de adesão do tiol nos mostraram que a rugosidade da amostra interfere significativamente na área de contato entre ponta e amostra e conseqüentemente na dispersão nas forças. Apesar disso...

Impacto da funcionalização de nanobastões de céria na reação de deslocamento gás-água; Impact of functionalization of ceria nanorods on water-gas shift reaction

Tathiana Midori Kokumai
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/02/2014 PT
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Nanobastões de céria (CeO2) funcionalizados com grupos amino foram utilizados como suporte em catalisadores de cobre para a reação de deslocamento gás-água (WGS). A funcionalização da superfície do óxido foi realizada visando uma melhor dispersão da fase metálica no suporte, através da interação entre o grupo amino e o precursor Cu2+, com a posterior correlação entre esta modificação e a atividade do catalisador. Utilizou-se o método hidrotérmico para a síntese dos nanobastões, que foram posteriormente funcionalizados com 3-(aminopropil)trimetoxisilano. A adição do precursor Cu2+ ao suporte foi feita via impregnação, seguida de calcinação e redução (ativação do catalisador), etapa na qual se formaram as nanopartículas metálicas (Cu0) suportadas. Comparando os catalisadores com suporte de céria pura e de céria funcionalizada, observou-se que de fato a funcionalização resultou na maior dispersão do Cu2+ na superfície. No entanto, ela causou a menor dispersão do metal (Cu0) após a redução, a diminuição da redutibilidade da céria superficial, a fragmentação dos bastões e o menor desempenho catalítico frente à reação de WGS. Visando a compreensão destes sistemas, verificou-se que a calcinação após a adição de Cu2+ na amostra funcionalizada formou uma camada de SiO2 na superfície da céria...

Functionalization of CNTS with maleic anhydride

Araújo, Rui Filipe; Paiva, M. C.; Proença, M. Fernanda R. P.; Silva, Carlos J. R.
Fonte: ChemOnTubes 2012 Publicador: ChemOnTubes 2012
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 ENG
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The outstanding properties of carbon nanotubes (CNTs) [1] are mainly related with their unique structural features. However, the high π-π staking between the tubes is a major drawback for their manipulation and interaction with other materials. Chemical functionalization has been used as a convenient tool to improve their performance in various applications [2]. The work reports the functionalization of multi-wall carbon nanotubes (MWCNTs) with maleic anhydride via a Diels-Alder addition reaction, performed in dimethyl sulfoxide (190 ºC) or 2-chorotoluene (150 ºC) for 24 hours. The product was characterized by thermogravimetric analysis (TGA) and the weight loss at 800 ºC was 11.9 and 3.7 % respectively. Potentiometric titration suggests that CNTs modified at 190 ºC remain predominantly in the anhydride form, while for CNTs modified at 150 ºC, the extent of hydrolysis is approximately 40 %. Maleic anhydride was also reacted with a model compound (anthracene) in dimethyl sulfoxide (190 ºC) and the hydrolysis of the product (0.025 mmol in 650 µL of DMSO-d6) was followed by 1H RMN upon addition of 0.166 mmol of DCl (40 % weight in D2O) (graphic in figure). The anhydride 1 was easily regenerated from the dicarboxylic acid 2 when this compound was heated at 185 ºC for 10 minutes. A similar behavior is expected for the modified CNTs.; Fundação para a Ciência e Tecnologia

Simple strategies for stable aqueous suspensions of carbon nanotubes

Paiva, M. C.; Araújo, Rui Filipe; Cunha, Eunice Paula Freitas; Gonçalves, Jordana; Melle-Franco, M.; Pereira, M.; Proença, M. Fernanda R. P.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Aula
Publicado em /04/2014 ENG
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Carbon nanotubes (CNT) are attractive nanoparticles for biological applications due to their broad absorption of light in the UV-Vis-NIR, NIR photoluminescence, unique Raman signature, photothermal response, and large surface area for the covalent and non-covalent conjugation of contrast agents and drugs, DNA/RNA. However, pristine CNT are highly hydrophobic and not biocompatible, requiring functionalization with hydrophilic molecules in order to form stable aqueous suspensions. Here, simple functionalization methods of perylene bisimides and pyrene, to render these polyaromatic molecules amphiphilic, will be presented. Bolaamphiphilic perylene bisimides (PBI) were prepared by the reaction of perylenetetracarboxylic dianhydride with -amino acids in good yield, using a simple protocol and avoiding complex purification methods. [1] Pyrene was modified by nitration followed by amination, and further reacted with maleic anhydride yielding carboxylic acid-functionalized pyrene. The CNT aqueous suspensions were studied by absorption and emission spectroscopy. Theoretical calculations were used to support the experimental observations. The possibility of CNT double functionalization (covalent and non-covalent) will be discussed based on CNT solubility studies in surfactant aqueous solutions. Pristine and covalently functionalized CNT...

Enantioselective Functionalization of Allylic C-H Bonds Following a Strategy of Functionalization and Diversification

Sharma, Ankit; Hartwig, John F.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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We report the enantioselective functionalization of allylic C-H bonds in terminal alkenes by a strategy involving the installation of a temporary functional group at the terminal carbon atom by C-H bond functionalization, followed by diversification of this intermediate with a broad scope of reagents. The method consists of a one-pot sequence of palladium-catalyzed allylic C-H bond oxidation under neutral conditions to form linear allyl benzoates, followed by iridium-catalyzed allylic substitution. This overall transformation forms a variety of chiral products containing a new C-N, C-O, C-S or C-C bond at the allylic position in good yield with high branched-to-linear selectivity and excellent enantioselectivity (ee ≤ 97%). The broad scope of the overall process results from separating the oxidation and functionalization steps; by doing so, the scope of nucleophile encompasses those sensitive to direct oxidative functionalization. The high enantioselectivity of the overall process is achieved by developing an allylic oxidation that occurs without acid to form the linear isomer with high selectivity. These allylic functionalization processes are amenable to an iterative sequence leading to (1,n)-functionalized products with catalyst-controlled diastereo- and enantioselectivity. The utility of the method in the synthesis of biologically active molecules has been demonstrated.

Surface Functionalization of Monodisperse Magnetic Nanoparticles

Lattuada, Marco; Hatton, T. Alan
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Artigo de Revista Científica Formato: 11308 bytes; application/pdf
EN
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We present a systematic methodology to functionalize magnetic nanoparticles through surface-initiated atom-transfer radical polymerization (ATRP). The magnetite nanoparticles are prepared according to the method proposed by Sun et al. (2004), which leads to a monodisperse population of ~ 6 nm particles stabilized by oleic acid. The functionalization of the nanoparticles has been performed by transforming particles into macro-initiators for the ATRP, and to achieve this two different routes have been explored. The first one is the ligand-exchange method, which consists of replacing some oleic acid molecules adsorbed on the particle surface with molecules that act as an initiator for ATRP. The second method consists in using the addition reaction of bromine to the oleic acid double bond, which turns the oleic acid itself into an initiator for the ATRP. We have then grown polymer brushes of a variety of acrylic polymers on the particles, including polyisopropylacrylamide and polyacrylic acid. The nanoparticles so functionalized are water soluble and show responsive behavior: either temperature responsive behavior when polyisopropylacrylamide is grown from the surface or PH responsive in the case of polyacrylic acid. This methodology has potential applications in the control of clustering of magnetic nanoparticles.; Singapore-MIT Alliance (SMA)

A fundamental study into the surface functionalization of soft glass microstructured optical fibers via silane coupling agents

Debs, J.; Ebendorff-Heidepriem, H.; Quinton, J.; Monro, T.
Fonte: IEEE-Inst Electrical Electronics Engineers Inc Publicador: IEEE-Inst Electrical Electronics Engineers Inc
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
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A method for the functionalization of surfaces within soft glass microstructured optical fibers has been developed, using self assembled monolayers (SAMs) of silane coupling agents. We demonstrate the use of measurements of the fiber capillary fill rate, as a positive test for a functionalized internal surface. A simple theoretical model is used for comparison with measured fill rates. During this work, adsorption kinetics for SAMs of octadecyltrichlororsilane onto lead silicate glass has been investigated. This work is a critically important first step for a plethora of applications in biophotonics, chemical fiber sensing as well offering promise for protecting fiber glass from degradation.; John E. Debs, Heike Ebendorff-Heidepriem, Jamie S. Quinton, and Tanya M. Monro

Comparison of surface functionalization techniques on silica and soft glasses for optical fibre sensing applications

Foo, H.; François, A.; Ebendorff-Heidepriem, H.; Sumby, C.; Monro, T.
Fonte: Australian Optical Society; CDROM Publicador: Australian Optical Society; CDROM
Tipo: Conference paper
Publicado em //2009 EN
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We report the comparison of three different surface functionalization processes using two different organosilanes, 3-mercaptopropyltrimethoxysilane (MTS) and 3-aminopropyltriethoxysilane (APTES) and polyelectrolytes (PE) on the internal surface of tellurite, bismuth, lead silicate F2 and silica glass capillaries. We find that polyelectrolyte and organosilane coatings can be attached on the internal surfaces of the capillary of all four glass materials. Furthermore, PE provides more specific binding sites for streptavidin than MTS and APTS for all four glass materials.; Tze Cheung Foo, Alexandre François, Heike Ebendorff-Heidepriem, Christopher J. Sumby and Tanya M. Monro

Regioselective functionalization of N-substituted beta and gamma-lactams.

Pitt, Michael Joseph
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //1992
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With the aim of developing methodology for direct regioselective functionalization of N-substituted β-lactams at exocyclic carbon adjacent to lactam nitrogen, free radical bromination of N-substituted β-lactams bearing activating substituents at that carbon has been investigated. Reaction of β-lactams bearing activating substituents at exocyclic carbon adjacent to nitrogen with N-bromosuccinimide resulted in regioselective bromination at the exocyclic carbon adjacent to nitrogen. The resultant product bromides are suitable for elaboration and the simplicity of this procedure points to its potential for use in synthesis. In particular, the direct exocyclic bromination of N-substituted β-lactams via this methodology provides a novel attractive alternative route to the synthesis of N-(α-halo-alkyl)-substituted lactams, which are of interest in the synthesis of β-lactam antibiotics. To demonstrate the synthetic utility of the direct exocyclic functionalization of N-substituted β-lactams, the elaboration of N-(α-bromoalkyl)-substituted β-lactams thus obtained was investigated. Reaction of ethyl α-bromo-2-oxo-1-azetidineacetate with allyltributyltin afforded the corresponding allylated derivative via radical carbon-carbon bond formation at the exocyclic carbon adjacent to nitrogen. Ionic carbon-carbon bond formation at the exocyclic carbon was achieved in a Wittig reaction and Lewis acid catalysed allylation and arylation reactions of this bromide. To examine the possibility of directing functionalization to the exocyclic carbon adjacent to lactam nitrogen in γ-lactams...

Functionalization of Nanocarbons for Composite, Biomedical and Sensor Applications

Kuznetsov, Oleksandr
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
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New derivatives of carbon nanostructures: nanotubes, nano-onions and nanocrystalline diamonds were obtained through fluorination and subsequent functionalization with sucrose. Chemically modified nanocarbons show high solubility in water, ethanol, DMF and can be used as biomaterials for medical applications. It was demonstrated that sucrose functionalized nanostructures can find applications in nanocomposites due to improved dispersion enabled by polyol functional groups. Additionally, pristine and chemically derivatized carbon nanotubes were studied as nanofillers in epoxy composites. Carbon nanotubes tailored with amino functionalities demonstrated better dispersion and crosslinking with epoxy polymer yielding improved tensile strength and elastic properties of nanocomposites. Reductive functionalization of nanocarbons, also known as Billups reaction, is a powerful method to yield nanomaterials with high degree of surface functionalization. In this method, nanocarbon salts prepared by treatment with lithium or sodium in liquid ammonia react readily with alkyl and aryl halides as well as bromo carboxylic acids. Functionalized materials are soluble in various organic or aqueous solvents. Water soluble nanodiamond derivatives were also synthesized by reductive functionalization of annealed nanodiamonds. Nanodiamond heat pretreatment was necessary to yield surface graphene layers and facilitate electron transfer from reducing agent to the surface of nanoparticles. Other carbon materials such as activated carbon and anthracite coal were also derivatized using reductive functionalization to yield water soluble activated carbon and partially soluble in organic solvents anthracite. It was shown that activated carbon can be effectively functionalized by Billups method. New derivatives of activated carbon can improve water treatment targeting specific impurities and bio active contaminants. It was demonstrated that functionalized carbon nanotubes are suitable for real time radiation measurements. Radiation sensor incorporating derivatized carbon nanotubes is lightweight and reusable. In summary...

Surface Functionalization of Graphene-based Materials

Mathkar, Akshay
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
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Graphene-based materials have generated tremendous interest in the past decade. Manipulating their characteristics using wet-chemistry methods holds distinctive value, as it provides a means towards scaling up, while not being limited by yield. The majority of this thesis focuses on the surface functionalization of graphene oxide (GO), which has drawn tremendous attention as a tunable precursor due to its readily chemically manipulable surface and richly functionalized basal plane. Firstly, a room-temperature based method is presented to reduce GO stepwise, with each organic moiety being removed sequentially. Characterization confirms the carbonyl group to be reduced first, while the tertiary alcohol is reduced last, as the optical gap decrease from 3.5 eV down to 1 eV. This provides greater control over GO, which is an inhomogeneous system, and is the first study to elucidate the order of removal of each functional group. In addition to organically manipulating GO, this thesis also reports a chemical methodology to inorganically functionalize GO and tune its wetting characteristics. A chemical method to covalently attach fluorine atoms in the form of tertiary alkyl fluorides is reported, and confirmed by MAS 13C NMR, as two forms of fluorinated graphene oxide (FGO) with varying C/F and C/O ratios are synthesized. Introducing C-F bonds decreases the overall surface free energy...

Intramolecular Direct Functionalization of Cyclopropanes via Silver-Mediated, Palladium Catalysis

Ladd, Carolyn L.
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
EN
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Au cours de la dernière décennie, le domaine de la fonctionnalisation directe des liens C–H a connu un intérêt croissant, en raison de la demande de processus chimiques moins dispendieux, plus efficaces et plus écologiques. . Les cyclopropanes représentent un motif structural souvent retrouvé dans des agents biologiquement actifs importants et dans des intermédiaires de synthèse permettant l'accès à des architectures complexes. Malgré leur valeur intrinsèque, la fonctionnalisation directe des cyclopropanes n’a pas été largement explorée. Ce mémoire traitera de deux méthodologies liées, mais tout aussi différentes, impliquant la fonctionnalisation directe des liens C–H cyclopropaniques impliquant des réactions intramoléculaires catalysées par un complex de palladium et assistées par l’argent. Le premier chapitre présentera d’abord un bref survol de la littérature sur les fondements de la fonctionnalisation directe ainsi que les contributions majeures réalisées dans ce domaine. L’accent sera notamment mis sur la fonctionnalisation des centres sp3 et sera souligné par des exemples pertinents. Les découvertes clés concernant le mécanisme et les cycles catalytiques de ces processus seront discutées. Le second chapitre décrira comment les 2-bromoanilides peuvent être utilisés pour accéder à des motifs particuliers de type spiro 3...

Fonctionnalisation covalente des nanotubes de carbone : propriétés, réversibilité et applications dans le domaine de l'électronique

Cabana, Janie
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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Le sujet général de cette thèse est l’étude de la fonctionnalisation covalente des nanotubes de carbone (CNT) et son application en électronique. Premièrement, une introduction au sujet est présentée. Elle discute des propriétés des CNT, des différentes sortes de fonctionnalisation covalente ainsi que des principales techniques de caractérisation utilisées au cours de la thèse. Deuxièmement, les répercussions de la fonctionnalisation covalente sur les propriétés des nanotubes de carbone monoparoi (SWNT) sont étudiées. Deux types de fonctionnalisation sont regardés, soit le greffage de groupements phényles et le greffage de groupements dichlorométhylènes. Une diminution de l’absorption optique des SWNT dans le domaine du visible-proche infrarouge est observée ainsi qu’une modification de leur spectre Raman. De plus, pour les dérivés phényles, une importante diminution de la conductance des nanotubes est enregistrée. Troisièmement, la réversibilité de ces deux fonctionnalisations est examinée. Il est montré qu’un recuit permet de résorber les modifications structurales et retrouver, en majorité, les propriétés originales des SWNT. La température de défonctionnalisation varie selon le type de greffons...

Functionalization of Carbon Nanotubes via Nitrogen Glow Discharge

Khare, Bishun; Wilhite, Patrick; Tran, Benjamin; Teixeira, Elico; Fresquez, Kenneth; Nna Mvondo, Delphine; Bauschlicher Jr., Charles; Meyyappan, M.
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artículo Formato: 170352 bytes; application/pdf
ENG
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7 pages, 9 figures.-- PMID: 16375320 [PubMed].; We have exposed single-wall carbon nanotubes (SWCNTs) to microwave-generated N2 plasma with the aim to functionalize the nanotubes. The results strongly depend on the distance between the discharge source and the sample, since nitrogen atoms generated can be lost due to recombination. No functionalization was observed when this distance was 7.0 cm. At intermediate distances (2.5 cm), the incorporation of nitrogen and oxygen onto the SWCNT was observed, while, at short distances (1 cm), products containing C≡N were also observed.; Ben Tran is on an internship from Milpitas High School and will start his freshman year at Stanford University in the Fall of 2005. Elico Teixeira is an undergraduate research intern from Santa Clara University.; Peer reviewed

Functionalization of metal nanoparticles with synthetic and natural hosts for the surface-enhanced spectroscopic detection of polycyclic aromatic hydrocarbons; Funcionalización de nanopartículas metálicas con receptores sintéticos y naturales para la detección de hidrocarburos policíclicos aromáticos mediante espectroscopías intensificadas por superficies

Sánchez-Cortés, Santiago; Guerrini, Luca; García-Ramos, José Vicente; Domingo, Concepción
Fonte: Sociedad Española de Óptica Publicador: Sociedad Española de Óptica
Tipo: Artículo Formato: 369203 bytes; application/pdf
ENG
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[EN] In this paper we study the ability of Surface-Enhanced Optical Techniques (Raman, IR and fluorescence) in the detection of pollutants such as polycyclic aromatic hydrocarbon. We have combined the optoelectronic properties of nanostructured coinable metals, leading to a remarkable sensitivity enhancement, and the selectivity imposed by a host molecule functionalization of the metal substrate. Host molecules of different nature and origin were tested in relation to their ability to interact with PAHs: synthetic and natural. The information resulting from this study can be applied in the design of chemical sensors for the detection of these important pollutants.; [ES] En este trabajo se estudia la capacidad de las técnicas espectroscópicas ópticas (Raman, IR y fluorescencia) en la detección de contaminantes como los hidrocarburos policíclicos aromáticos. Hemos combinado las propiedades optoelectrónicas de metales nanoestructurados acuñables, en los que la sensibilidad es enormemente incrementada, y la selectividad proporcionada por las moléculas receptoras con las que se funcionaliza el sustrato metálico. Para ello se han utilizado moléculas receptoras de naturaleza diferente (sintéticos y naturales) capaces de interaccionar con hidrocarburos policíclicos aromáticos. La información derivada de este trabajo podrá ser utilizada en el diseño de sensores químicos para la detección de estos importantes contaminantes ambientales.; We acknowledge project FIS2004-00108 from Dirección General de Investigación...

A concise and scalable strategy for the total synthesis of dictyodendrin B based on sequential C?H functionalization

Pitts, Andrew K.; O'Hara, Fionn; Snell, Robert H.; Gaunt, Matthew J.
Fonte: Wiley Publicador: Wiley
Tipo: Article; accepted version
EN
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This is the author accepted manuscript. The final version is available from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/anie.201500067/abstract.; A sequential C-H functionalization strategy for the synthesis of the marine alkaloid dictyodendrin?B is reported. Our synthesis begins from commercially available 4-bromoindole and involves six direct functionalizations around the heteroarene core as part of a gram-scale strategy towards the natural product.; We are grateful to AstraZeneca, Pfizer, and EPSRC (A.K.P., F.O. and R.H.S.) and the ERC and EPSRC for fellowships (M.J.G.).

Side-Wall Functionalization of Multi-Walled Carbon Nanotubes with t-Butyl Diazoacetate

Rogel-Hernández,Eduardo; Alonso-Nuñez,Gabriel; Camarena,Juan P.; Espinoza-Gómez,Heriberto; Aguirre,Gerardo; Paraguay-Delgado,Francisco; Somanathan,Ratnasamy
Fonte: Sociedad Química de México A.C. Publicador: Sociedad Química de México A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2011 EN
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The covalent functionalization of multiwall carbon nanotubes (MWCNT) and its characterization techniques are reported. MWCNT were functionalized with tert-butyldiazoacetate to give methano-bridged ester group. Functionalized carbon nanotube by ester and its hydrolyzed carboxylic acid were characterized by high resolution electron microscope techniques, scanning electron microscopy (SEM), transmission electron microscopy (TEM) to study the shape a structure and fast Fourier transform infrared (FT-IR) to evaluate types of binding.

Functionalization of a natural biopolymer with aliphatic polyamines and its sorption properties for vanadium removal from aqueous solutions

Mnisi,Robert L.; Ndibewu,Peter P.; Mokgalaka,Ntebogeng S.
Fonte: South African Journal of Chemistry Publicador: South African Journal of Chemistry
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
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A low-cost natural adsorbent, Moringa oleifera, was investigated as a potential alternative for currently costly methods of removing vanadium from contaminated aqueous solutions. The unmodified bark was characterized using techniques such as N2-BET, SEM, XRD and FTIR spectroscopy, CHNS elemental determination and AA spectroscopy. Results showed a relatively small surface area, motivating surface functionalization to enhance adsorption capacity. Chemical modification was performed using four aliphatic polyamines: ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA). The modified bark was characterized and then investigated to determine its efficiency in removing VO2+ from aqueous solutions. The bark had a mesoporous amorphous structure and was enriched with N and S groups. FTIR absorption frequencies also revealed that polyamines were indeed immobilized on the adsorbent surface. The polyamine density was calculated and was in the order of EDA>DETA>TETA>TEPA, whereas the adsorption efficiency with VO2+ was in the order DETA>EDA>TETA>TEPA. Adsorbent amination was enhanced by up to 26 % and adsorption performance improved by up to 155 %. It was, therefore, concluded that chemical modification of M. oleifera using polyamines enhances adsorption of VO2+ from aqueous solutions. This can...