[pt] As ligas metálicas têm sido amplamente estudadas, visando atender aplicações onde propriedades físicas e químicas diferenciadas se fazem necessárias. Nesse sentido, merecem destaque as ligas voltadas ao recobrimento de substratos metálicos, tendo-se como objetivo a proteção do substrato em ambientes corrosivos. Sendo assim, a presente pesquisa propõe abordar um método de síntese de ligas de Cu-Ni em substratos de cobre através da decomposição térmica do nitrato de níquel, e subsequentemente a redução do óxido NiO formado, mediante redução com H2 a 350 graus Celsius e tratamento térmico na mesma atmosfera a 800 graus Celsius, com tempos variados (3, 4 e 5h), para estimular a difusão do níquel produzido no interior da matriz de Cu. Os filmes serão caracterizados via microscopia eletrônica de varredura (MEV), tanto em sessões transversais, quanto panorâmico, além da difração de raios-x (DRX) com incidência rasante, visando-se identificar a liga Cu-Ni produzida. Os resultados sugerem que o processo proposto foi bem-sucedido, permitindo um amplo recobrimento do substrato e a subsequente difusão do Ni produzido, o que permitiu a identificação, em todas as amostras, da liga de interesse. As amostras selecionadas serão futuramente utilizadas para ensaios de microdureza, bem como de eletro-corrosão, sendo o comportamento medido comparando-se com o substrato puro. Espera-se que a presença do recobrimento eleve a resistência à abrasão, bem como dificultar a corrosão do cobre presente. / [en] Metal alloys has been extensively studied to light upon applications where differentiated physical and chemical properties are required. In this context, its value highlighting the alloys for the coating of metallic substrates with the objective of protecting the substrate in corrosive environments. The present work proposes to approach a method of synthesis of Cu-Ni alloys in copper substrates through the thermal decomposition of nickel nitrate and subsequently to discount the NiO oxide formed by reduction with H2 at 350 degrees Celsius and heat treatment in the same atmosphere at 800 degrees Celsius with (3, 4 and 5h) to stimulate the diffusion of the nickel produced inside the Cu matrix. The films were then characterized by scanning electron microscopy (SEM) in both cross-sectional and panoramic sessions, in addition to X-ray diffraction (XRD) with low incidence, aiming to identify Cu-Ni alloy produced. The results suggest that the proposed process was successful, allowing a wide coating of the substrate and subsequent diffusion of Ni produced, which allowed the identification in all samples of the alloy of interest. Selected samples will be used in the future for microhardness tests, as well as for electro-corrosion, and the measured behavior is compared to that observed for pure substrate. The presence of the coating is expected to raise the abrasion resistance as well as to hinder the corrosion of the copper present.

Este trabalho descreve a síntese e caracterização dos compostos de adição obtidos pela reação entre os monocloroacetatos (CA) e dicloroacetatos (DCA) de lantanídeos (III) com a quinolina-N-óxido (QNO), na presença de etanol e ortoformiato de trietila. Os compostos foram obtidos na forma sólida e caracterizados por análise elementar, testes de solubilidade, medidas de condutância eletrolítica, difração de raios X (método do pó), espectros de absorção na região do infravermelho, espectros de absorção na região do visível dos compostos de Nd, espectros de emissão dos compostos de Eu e análise térmica. Os experimentos de análise térmica permitiram estudar o comportamento térmico dos compostos. A associação dos resultados de análise elementar e termogravimétrica permitiu sugerir as seguintes fórmulas mínimas: a) Ln(DCA)3.yQNO.wEtOH onde, y = w = 8/9 para Ln= La; y = w = 1 para Ln= Ce; y = 1 e w =¾ para Ln= Pr, Nd e Sm; y = 1 e w = O para Ln= Eu ao Lu e Y. b) Ln(CA)3.QNO, onde Ln= La ao Ho e Y. Os compostos não são higroscópicos, e possuem coloração bege, em sua grande maioria. São solúveis em DMF, DMSO, HMPA e água, e insolúveis em hexano, ciclohexano, dimetoxipropano, benzeno, clorofórmio, cloreto de metileno, tolueno, acetonitrila e acetona. As medidas de condutância, em solução de DMF, revelaram que os compostos se comportam como não eletrólitos, indicando que os ânions CA e DCA estão coordenados ao íon Ln3+. Os difratogramas de raios X ( método do pó) mostraram que os compostos de adição de dicloroacetatos possuem três séries isomorfas. Os espectros de absorção no infravermelho indicaram que a coordenção da QNO e dos ânions CA e DCA ocorre através do átomo de oxigênio, mas não permitiram evidenciar a coordenção do EtOH nos compostos de adição de dicloroacetatos, porém os resultados de análise térmica confirmaram a presença do etanol para os compostos de La ao Sm. As associações das técnicas auxiliaram na definição da estequiometria e existência das séries isomorfas. Os espectros de absorção dos compostos de Nd mostraram que as interações Nd3+- ligantes são de caráter eletrostático. Baseando-se nas transições 4I9/2 → 4G5/2, 2G7/2 foi possível determinar o parâmetro nefelauxético [β = 0,990 (CA) e β = 0,993 (DCA)], o fator de covalência [b1/2 = 0,070 (CA) e b1/2 = 0,0502 (DCA)] e o parâmetro de Sinha [δ = 1,01 (CA) e δ = 0,705 (DCA)]. Os espectros de emissão dos compostos de Eu, registrados a 77 K, sugeriram a simetria C3v para o composto de Eu(CA)3.QNO e C2v para o composto Eu(DCA)3.QNO. As curvas termoanalíticas evidenciaram que o processo de decomposição térmica ocorre em multi-etapas e que o produto final é o respectivo óxido. / This work describes the synthesis and characterization of the addition compounds obtained between lanthanide (III) mono and dichloroacetates with Quinoline-N-oxide (QNO) in the presence of ethanol and triethyl orthoformate. These compounds were obtained in the solid form and characterized by elemental analysis, solubility tests, electrolytic condutance measures, X-ray diffraction (powder method), infrared absorption spectroscopy, visible absorption spectroscopy of the Nd compounds, emission spectroscopy of the Eu compounds and thermal analysis. The thermal analysis experiments allowed studying the thermal behavior of the compounds. The association of the results of elemental analysis and thermogravimetry allowed to suggest the minimum formule: a) Ln(DCA)3.yQNO.wEtOH, where y = w = 8/9 when Ln = La; y = w = 1 when Ln = Ce; y = 1 and w = 3/4 when Ln = Pr, Nd and Sm; y = 1 and w = 0 when Ln = Eu to Lu and Y. b) Ln(CA)3.QNO, where Ln= La -Ho e Y. The compounds are not hygroscopic and are beige coloration. They are soluble in DMF, DMSO, HMPA and water, but they are insoluble in hexane, ciclohexane, dimetoxipropane, benzene, chloroform, methylene chloride, toluene, acetonitrile and acetone. In DMF solution, the conductance measurements revealed that the compouds behave as non-electrolytes, indicating that CA and DCA ions are coordinated to the ion Ln3+. X-ray patterns suggest that the addition compounds of dichloroacetates and monochloroacetates have, respectively, three and four isomorphous series. The infrared spectra indicated that ligand and anions coordination to Ln3+ occurs through the oxygen atom, but they did not confirm the EtOH coordination in the addition compounds of dichloroacetates, however the results of thermal analysis confirmed the alcohol presence in the La to Sm complexes. The techniques association support in stoichiometry definition and isomorphic series. The absorption spectra of the Nd compounds suggest that the Nd3+-ligand interactions are of electrostatic character. Based in the 4I9/2 → 4G5/2, 2G5/2 transitions was possible to determine the spectroscopic parameters: nephelauxetic parameter [β = 0,990 (CA) and β = 0,993 (DCA)], covalency factor [bl/2 = 0,070 (CA) and b1/2 = 0,0502 (DCA)] and Sinha\'s parameter [δ = 1,01 (CA) and δ = 0,705 (DCA)]. The emission spectra of the Eu compounds, at 77 K, suggest that the symmetry for the Eu3+ ions is C3v for Eu(CA)3.QNO and C2v for Eu(DCA)3.QNO. The thermoanalytical curves evidenced that the thermal decomposition process occurs in multi-stages and that the final product is the respective oxide.

Made available in DSpace on 2014-06-11T19:23:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-09-18Bitstream added on 2014-06-13T19:50:19Z : No. of bitstreams: 1 tranquilin_rl_me_bauru.pdf: 1401003 bytes, checksum: 671b0d9181df24fb0ba937b77bcac1d8 (MD5) / O estudo das propriedades fotoluminescentes nos diferentes materiais tanto orgânicos e inorgânicos tem despertado muito o interesse da comunidade científica. Dentre os molibdatos, destacamos o molibdato de bário (BAMoO4) devido suas propriedades ópticas e termoelétricas que junto com suas emissões luminescentes no azul, verde e laranja o tornam um importante material. Neste trabalho, pós de molibdato de bário foram sintetizados pelo método de coprecipitação e processados a 140 ºC por diferentes tempos, em hidrotermal assistido por irradiação de microondas. A caracterização dos pós foi realizada através de difração de raios - X, espectroscopia Raman, absorção na região do infravermelho. As análises microestruturais e morfológicas destes pós foram realizadas através das técnicas de microscopia eletrônica de varredura por canhão de elétrons e microscopia de Transmissão. As propriedades ópticas foram verificadas por meio da espectroscopia na região do ultravioleta visível e medidas de fotoluminescência. / The study of properties in different photoluminescent both organic and inorganic materials has attracted much interest form the scientific community. Among the molybdate,. the highlight of barium molybdate (BaMoO4) because their optical properties and thermoelectric that along with its luminescent emission in blue, green and orange make it an important material. In this work of barium molybdate were synthesized by co-precipitation method and processed at 140 ºC for diferent times in hydrothermal assisted by microwave irradiation. The characterization of powders was carried out by-ray diffraction - X, Raman spectroscopy, absorption in the infrared region. The micro structural and morphological analyses of these powders were performed using the techniques of field emission gun scanning electronic microscopy and by trasmission electronic microscopy. The optical properties were observed by spectroscopy in region the ultraviolet visible and measures of photoluminescence.

[pt] Nos últimos anos muitos esforços foram realizados para obtenção de materiais capazes de explorar eficientemente a conversão de energia solar. Em particular, a geração de combustíveis por fotocatálise retém grande interesse devido às suas propriedades intrínsecas de promover reações com variação de energia positiva, possibilitando seu armazenamento em compostos químicos. A eficiência desses processos, entretanto, é limitada pela fotoativação dos principais fotocatalisadores no espectro UV, desperdiçando grande parte da energia solar presente no Visível. Neste trabalho foi investigada a influência no desempenho de fotoativação de heteroestruturas de titanatos de Fe e Cu crescidos sobre TiO2 para produção de gás H2 por fotólise da água utilizando luz Visível. As amostras foram preparadas segundo rota por impregnação via úmida e pós-tratamento térmico, em que óxidos metálicos foram formados na superfície de partículas de TiO2 com posterior interdifusão e formação de fases ternárias de Fe2TiO5 e Cu3TiO4. Realizou-se a caracterização dos materiais por meio das técnicas de DRX, DSC, TGA, MEV/EDS, DRS, PLS e Fisissorção de N2. Os resultados obtidos confirmaram a formação dos materiais, sugerindo a criação de heteroestruturas do tipo PN para as amostras contendo Fe e a formação de fase dopada rutilo Cu para as contendo Cu. A atividade fotocatalítica foi avaliada em teste de desempenho realizado em sistema reacional construído na execução do trabalho. Os testes permitiram identificar resultados preliminares promissores de atividade fotocatalítica para as amostras contendo Fe em sua estrutura, que demonstraram uma significativa atividade fotocatalítica no espectro Visível. / [en] In recent years many efforts have been made to obtain materials capable of efficiently exploiting the potential of solar energy conversion. In particular, the generation of fuels by photocatalysis retains great interest due to its intrinsic properties of promoting up-hill reactions, with a positive free energy variation, allowing its storage in chemical compounds. The efficiency of these processes, however, is usually limited by the photoactivation of main photocatalysts in UV spectrum, wasting much of the solar energy present in visible spectrum. This work investigates the influence on photoactivation performance of heterojunctions with Fe and Cu titanate grown on TiO2 for H2 gas production under Visible light by water-splitting. The samples were prepared according route by wet impregnation followed by post-heating treatment, where metal oxides were formed on TiO2 particles surface with subsequent interdiffusion and formation of ternary phases of Fe2TiO5 e Cu3TiO4. The materials were characterized by DRX, DSC, TGA, MEV / EDS, DRS, PLS and N2 Physisorption techniques. The results confirmed the materials sucessful preparation, suggesting the formation of PN-type heterostructures for Fe-containing samples and a rutile-Cu doped phase for Cu-containing samples. The photocatalytic activity was evaluated in a performance test using a photoreactor system built in as part of this work. The tests allowed to identify promising preliminary results for Fe-containing samples, which demonstrated a significant photocatalytic activity in the Visible spectrum.

Hydroxyapatite (HAP) coatings are used in orthopaedic surgery for bone regeneration. Current methods of phase quantification of HAP coatings suffer from drawbacks. A novel methodology of quantitative phase analysis of HAP coatings has been devised and validated. This method, based on whole pattern fitting with a fundamental parameters approach, incorporates amorphous calcium phosphate (ACP) and apatite phases into structural refinements. A comparison of the structural and chemical properties of plasma sprayed (PS) and novel electrodeposited (ED) HAP coatings has been conducted. ED coatings contained less ACP and more preferred orientation than the PS coatings, although the stoichiometry was similar. In vitro investigations of PS and ED coatings in simulated body fluid and foetal calf serum revealed that both are bioactive. A carbonated apatite layer produced on the ED coatings was -0.7μm thick with a stoichiometry and chemical constituents similar to that of natural bone apatite. PS coatings produced a nanocrystalline carbonated apatite layer (-4μm). For the first time it has been possible to model crystalline HAP and nanocrystalline apatite as independent phases and obtain accurate lattice parameters for each. A positive linear correlation has been made between microstrain and the solubility of HAP and carbonated apatites. Dissolution studies have shown that the behaviour of HAP and carbonated apatite is dominated by crystallite size at low undersaturation and by crystallite size and microstrain at high undersaturation for crystallites between -30OA- 1000A. Metastable equilibrium occurred for crystallites <_400A at low undersaturation. Carbonate content did not affect the solubility or dissolution behaviour. A novel technology for coating polymeric tape with HAP for potential use in anterior cruciate ligament reconstruction has been devised. Mechanical tests have demonstrated that no adverse properties are induced by the coating technology. Cell culture studies have shown that the HAP layer is capable of enhanced attachment, proliferation and differentiation of osteoblast cells compared to uncoated tape.

Orientador: Élson Longo / Banca: Fenelon Martinho Lima Pontes / Banca: Alberthmeiry Teixeira Figueiredo / - O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: O estudo das propriedades fotoluminescentes nos diferentes materiais tanto orgânicos e inorgânicos tem despertado muito o interesse da comunidade científica. Dentre os molibdatos, destacamos o molibdato de bário (BAMoO4) devido suas propriedades ópticas e termoelétricas que junto com suas emissões luminescentes no azul, verde e laranja o tornam um importante material. Neste trabalho, pós de molibdato de bário foram sintetizados pelo método de coprecipitação e processados a 140 ºC por diferentes tempos, em hidrotermal assistido por irradiação de microondas. A caracterização dos pós foi realizada através de difração de raios - X, espectroscopia Raman, absorção na região do infravermelho. As análises microestruturais e morfológicas destes pós foram realizadas através das técnicas de microscopia eletrônica de varredura por canhão de elétrons e microscopia de Transmissão. As propriedades ópticas foram verificadas por meio da espectroscopia na região do ultravioleta visível e medidas de fotoluminescência. / Abstract: The study of properties in different photoluminescent both organic and inorganic materials has attracted much interest form the scientific community. Among the molybdate,. the highlight of barium molybdate (BaMoO4) because their optical properties and thermoelectric that along with its luminescent emission in blue, green and orange make it an important material. In this work of barium molybdate were synthesized by co-precipitation method and processed at 140 ºC for diferent times in hydrothermal assisted by microwave irradiation. The characterization of powders was carried out by-ray diffraction - X, Raman spectroscopy, absorption in the infrared region. The micro structural and morphological analyses of these powders were performed using the techniques of field emission gun scanning electronic microscopy and by trasmission electronic microscopy. The optical properties were observed by spectroscopy in region the ultraviolet visible and measures of photoluminescence. / Mestre

Made available in DSpace on 2014-12-17T14:54:59Z (GMT). No. of bitstreams: 1 ElderECO_TESE_Capa_ate_pag86.pdf: 3877192 bytes, checksum: d9b068e5eaa76a69d5a1fa1f245dbc5d (MD5) Previous issue date: 2011-09-02 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The search for ever smaller device and without loss of performance has been increasingly investigated by researchers involving applied electromagnetics. Antennas using ceramics materials with a high dielectric constant, whether acting as a substract element of patch radiating or as the radiant element are in evidence in current research, that due to the numerous advantages offered, such as: low profile, ability to reduce the its dimensions when compared to other devices, high efficiency of ratiation, suitability the microwave range and/or millimeter wave, low temperature coefficient and low cost. The reason for this high efficiency is that the dielectric losses of ceramics are very low when compared to commercially materials sold used in printed circuit boards, such as fiberglass and phenolite. These characteristics make ceramic devices suitable for operation in the microwave band. Combining the design of patch antennas and/or dielectric resonator antenna (DRA) to certain materials and the method of synthesis of these powders in the manufacture of devices, it s possible choose a material with a dielectric constant appropriate for the design of an antenna with the desired size. The main aim of this work is the design of patch antennas and DRA antennas on synthesis of ceramic powders (synthesis by combustion and polymeric precursors - Pe- chini method) nanostructured with applications in the microwave band. The conventional method of mix oxides was also used to obtain nanometric powders for the preparation of tablets and dielectric resonators. The devices manufactured and studied on high dielectric constant materials make them good candidates to have their small size compared to other devices operating at the same frequency band. The structures analyzed are excited by three different techniques: i) microstrip line, ii) aperture coupling and iii) inductive coupling. The efficiency of these techniques have been investigated experimentally and compared with simulations by Ansoft HFSS, used in the accurate analysis of the electromagnetic behavior of antennas over the finite element method (FEM). In this thesis a literature study on the theory of microstrip antennas and DRA antenna is performed. The same study is performed about the materials and methods of synthesis of ceramic powders, which are used in the manufacture of tablets and dielectric cylinders that make up the devices investigated. The dielectric media which were used to support the analysis of the DRA and/or patch antennas are analyzed using accurate simulations using the finite difference time domain (FDTD) based on the relative electrical permittivity (er) and loss tangent of these means (tand). This work also presents a study on artificial neural networks, showing the network architecture used and their characteristics, as well as the training algorithms that were used in training and modeling some parameters associated with the devices investigated / A busca por dispositivos cada vez menores e sem perda de desempenho vem sendo cada dia mais investigada pelos pesquisadores da ?rea envolvendo eletromagnetismo apli- cado. Antenas utilizando materiais cer?micos com uma alta constante diel?trica, sejam elas atuando como substrato do elemento patch radiante ou como sendo o pr?prio ele- mento radiante est?o em evid?ncia nas pesquisas atuais, isso devido ?s in?meras vantagens que apresentam, tais como: baixo perfil, capacidade de redu??o de suas dimens?es (quando comparado a outros dispositivos), alta efici?ncia de radia??o, adequabilidade a faixa de micro-ondas e/ou ondas milim?tricas, baixo coeficiente de temperatura e baixo custo. A raz?o para essa alta efici?ncia ? que as perdas diel?tricas das cer?micas s?o muito baixas, quando comparadas ?s dos materiais comercialmente usados em placas de circuito impresso, tais como: fibra de vidro e fenolite. Essas caracter?sticas tornam os dispositivos cer?micos adequados para operar na faixa de micro-ondas. Aliando o projeto de antenas patch e/ou antenas ressoadoras diel?tricas (DRA) ao uso de certos materiais e ao m?todo de s?ntese desses p?s na fabrica??o dos dispositivos, ? poss?vel escolher um material com uma determinada constante diel?trica para o projeto de uma antena com o tamanho desejado. O objetivo principal deste trabalho consiste no projeto de antenas patches e antenas DRA sob s?ntese de p?s cer?micos (s?ntese por combust?o e por precursores polim?ricos - m?todo Pechini) nanoestruturados para aplica??es na faixa de micro-ondas. O m?todo convencional de mistura de ?xidos tamb?m foi utilizado na obten??o de p?s nanom?tricos para a confec??o das pastilhas e ressoadores diel?tricos. Os dispositivos fabricados e estudados sobre materiais de alta constante diel?trica os tornam bons candidatos ? fabrica??o de dispositivos e circuitos de dimens?es reduzidas quando comparado aos outros dispositivos tradicionais operando na mesma faixa de frequ?ncia. As estruturas analisadas s?o excitadas por tr?s diferentes t?cnicas: i) linha de microfita, ii) acoplamento por abertura e iii) acoplamento indutivo. A efici?ncia dessas t?cnicas de alimenta??o s?o investigadas experimentalmente e comparada com simula??es realizadas pelo Ansoft HFSS, utilizado na an?lise precisa do comportamento eletromagn?tico das antenas atrav?s do m?todo dos elementos finitos (FEM). Nesta tese um estudo bibliogr?fico sobre teoria de antenas de microfita e antenas DRA ? realizado. O mesmo estudo ? realizado a respeito dos materiais e dos m?todos de s?ntese dos p?s cer?micos que s?o utilizados na fabri- ca??o das pastilhas e dos cil?ndros diel?tricos que compor?o os dispositivos investigados. Os meios diel?tricos os quais serviram de suporte na an?lise das antenas patch e/ou DRA s?o analisados atrav?s de simula??es precisas utilizando o m?todo das diferen?as finitas no dom?nio do tempo (FDTD) com base na permissividade el?trica relativa (er) e tangente de perda desses meios (tand). Este trabalho ainda apresenta um estudo em redes neurais artificiais, evidenciando a arquitetura de rede utilizada e suas caracter?sticas, bem como os algoritmos de treinamento que foram usados no treinamento e na modelagem de alguns par?metros associados aos dispositivos investigados

Cette thèse concerne le développement de nanocristaux (NCs) cœur/coquille d'InP/ZnS émettant dans le proche infrarouge pour l'imagerie biologique. Dans la synthèse chimique des NCs cœur d'InP, nous avons utilisé la phosphine générée in situ comme précurseur de phosphore en combinaison avec le myristate d'indium comme précuseur d'indium et l'1-octadécène comme solvant. Les NCs obtenus sont hautement cristallins et présentent une fluorescence dans la gamme 720-750 nm, selon leur taille. La croissance d'une ou deux monocouches (coquille) de ZnS sur la surface des NCs d'InP a considérablement amélioré leur rendement quantique de fluorescence. Nous avons de plus étudié le transfert de phase de ces NCs InP/ZnS du milieu organique au milieu aqueux en utilisant diverses molécules hydrophiles contenant un groupe thiol. En particulier, nous nous sommes intéressés au transfert de phase avec des molécules zwitterioniques tels que la penicillamine et la cystéine afin d'obtenir une taille hydrodynamique compacte, et de réduire les interactions non-spécifiques en milieu biologique. Dans l'étude du transfert de phase, l'accent a été mis sur la stabilité colloïdale des NCs et sur la préservation de leur efficacité de fluorescence en milieu aqueux. La cytotoxicité des NCs InP/ZnS fonctionnalisés avec la pencillamine a été évaluée en culture cellulaire. Puis la bio-distribution de ces NCs a été étudiée dans des souris vivantes par imagerie de fluorescence grâce à leur émission dans le proche infrarouge. Pour finir, les fonctionnalisations de NCs InP/ZnS d'une part avec un peptide de pénétration cellulaire, d'autre part avec des agents de contraste IRM (complexes de gadolinium) et enfin avec un nombre contrôlé de molécules streptavidine ont été explorées, démontrant le grand intérêt de ces NCs pour l'imagerie biologique. Mots clés: phosphure d'indium, boîtes quantiques, nanocristaux, imagerie biologique de fluorescence, infrarouge, transfert de phase, fonctionnalisation de surface / This thesis concerns the development of near infrared (NIR) emitting InP/ZnS core/shell nanocrystals for biological imaging. In situ generated phosphine gas was used as the phosphorous precursor, indium myristate as the In precursor and 1-Ocadecene as the solvent to produce InP NCs with emission in the range of 720-750 nm. Growth of 1-2 monolayers of a ZnS shell on the surface of the InP NCs strongly improves their quantum yield. Next, we studied the phase transfer of the obtained InP/ZnS NCs to aqueous medium with various thiol group containing ligands. Emphasis is put on the colloidal stability and the retention of fluorescence quantum efficiency during the transfer. Zwitterionic ligands such as pencillaime and cysteine have been studied in view of their biological interest in providing compact size and reduced non-specific interaction with cells. The cytotoxicity of pencillamine capped InP/ZnS NCs has been evaluated in cell culture. The NIR emitting properties of the QDs have been exploited to their study bio-distribution in mice by fluorescence imaging. In addition, functionalisation of the InP/ZnS NCs with a cell penetrating peptide, with a MRI contrast agent (gadolinium complex) and with a controlled number of streptavidin molecules have been explored to demonstrate the large interest of InP/ZnS NCs in biology. Key words: Indium phosphide, quantum dots, near infrared fluorescence imaging, phase transfer, surface functionalisation

Atomically flat colloidal semiconductor CdSe nanoplatelets (NPLs) with precisely controlled thickness possess a range of unique optoelectronic properties. Here, we study the growth of CdSe, CdTe, and CdS NPLs with the aim of synthesizing thicker NPLs in order to extend their optical activity further into the lower energy/larger wavelength range. We employ cadmium halides, which lead to faster reaction kinetics as confirmed by control experiments with cadmium hydroxide as a Cd-precursor. Addition of halides in all cases led to the formation of thicker NPL species, as compared with the corresponding syntheses without these additives. Analysis of a recent theoretical model of the platelet growth mechanism confirms an earlier suggestion that reducing both the reaction enthalpy and the surface energy of CdSe, by replacing acetate ligands with chloride ions, should indeed lead to thicker NPLs as observed. We noticed a formation of Cd0-metal nanoparticles in the first stage of the synthesis by preparing the Cd-precursor, which is another key finding of our work. We assume that these particles can serve as an active cadmium source facilitating the growth of the NPLs. The resulting 6 ML CdSe NPLs exhibited bright photoluminescence with quantum yield of up to 50%, exceptionally narrow spectrum centered at 582 nm with full width at half-maximum of approx. 11 nm, and small Stokes shift of 2 nm. Moreover, we demonstrated the synthesis of heterostructured core/shell CdSe/CdS NPLs based on 6 ML CdSe platelets, which also exhibited bright fluorescence. This work shows the possibility to overcome energetic barrier limiting the size (thickness) control by using appropriate promoters of the growth of CdSe, CdTe, and CdS 2D structures.

The on-surface reactions of 10-bromo-10'-(2,6-dimethylphenyl)-9,9'-bianthracene on Au(111) surface have been investigated by a combination of bond-resolved scanning tunneling microscopy, scanning tunneling spectroscopy, and tightbinding and mean-field Hubbard calculations. The reactions afford the synthesis of two open-shell nanographenes (1a and 1b) exhibiting different scenarios of all-carbon magnetism. 1a, an allbenzenoid nanographene with previously unreported triangulenelike termini, contains a high proportion of zigzag edges, which endows it with an exceedingly low frontier gap of 110 meV and edge-localized states. The dominant reaction product (1b) is a non-benzenoid nanographene consisting of a single pentagonal ring in a benzenoid framework. The presence of this nonbenzenoid topological defect, which alters the bond connectivity in the hexagonal lattice, results in a non-Kekulé nanographene with a spin S = ½, which is detected as a Kondo resonance. Our work provides evidence of all-carbon magnetism, and motivates the use of topological defects as structural elements toward engineering agnetism in carbon-based nanomaterials for spintronics.