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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

The Design, Syntheses, and Photophysics of Novel Pt(II) Polypyridyl Arylacetylides and Arylthiolates

Prusakova, Valentina 07 December 2012 (has links)
No description available.
22

Sulphonamido-phosphorus nickel complexes for the selective oligomerisation of olefins - Exploring dissymmetric ligands and supramolecular strategies / Complexes sulfonamido-phosphine du nickel pour l'oligomérisation sélective des oléfines, exploration de ligands dissymétriques et de stratégies supramoléculaires

Boulens, Pierre 17 December 2014 (has links)
Les alpha oléfines linéaires courtes sont des molécules de base en pétrochimie donc le marché est en constante augmentation notamment pour les oléfines légères (butène-1, hexène-1, octène-1). Ces oléfines, utilisées massivement dans l’industrie des plastiques, sont produites par la réaction catalytique d’oligomerisation de l’éthylène. IFPEN a contribué à développer plusieurs procédés homogènes d’oligomérisation de l’éthylène (AlphaButol, AlphaHexol, AlphaSelect) à base des complexes de titane, chrome ou zirconium. A travers une collaboration avec l’Université d’Amsterdam de nouvelles stratégies de développement de ligands ont été entreprises afin de rendre les catalyseurs à base de nickel sélectifs pour cette transformation. Ainsi, une approche supramoléculaire basée sur des interactions par liaison hydrogène, jusqu’alors décrite pour les métaux nobles, a été développée et appliquée aux complexes de nickel. Des complexes organométalliques originaux ont pu être générés et les interactions supramoléculaires ont été caractérisées par diffraction aux rayons X notamment. Ces complexes se présentent sous forme zwitterionique et sont formés par la combinaison de deux ligands simples donneurs et/ou accepteurs d’hydrogène. Ces complexes se sont avérés très actifs vis-à-vis de l’éthylène et ne nécessite pas l’ajout d’activateur du fait de la présence d’une liaison nickel-carbone réactive. Ils ont permis d’accéder à des sélectivités très importantes en butène-1. Appuyé par des expériences in situ et l’évaluation en catalyse de plusieurs complexes aux propriétés électroniques et stériques variées, cette approche a permis d’identifier l’espèce active et de mesurer l’impact de plusieurs descripteurs permettant de moduler la sélectivité et l’activité de la réaction catalytique en profondeur. / The demand for short linear alpha olefins is constantly increasing and motivates the development of robust and selective catalysts. In this thesis, several libraries of phosphorus ligands with the capacity to form dissymmetric or supramolecular assemblies were synthesized. The variability observed within the aminophosphine libraries, clearly reflected by the various tautomeric equilibrium of the ligand, was also observed in the nickel complexes as a single ligand could generate several complexes with different structures. Sulphonyliminobisphosphine were then introduced as a new class of ligands. These precursors rearrange in the presence of nickel to generate diphosphinamine nickel complexes. Activated by MAO, these complexes are active in the reaction of ethylene oligomerisation and produce short chain olefins. A new approach that forms stable supramolecular nickel complexes was developed by combining two phosphorus ligands with Ni(0). These complexes stabilised by hydrogen bonding are directly active in the reaction of ethylene oligomerisation with some catalysts leading to high selectivity to 1-butene (up to 84%). To understand the origin of that selectivity, the scope of complexes was extended to ligands with different steric and electronic properties. Their evaluation in the reaction of ethylene oligomerisation evidenced a relation between the catalyst structure and the selectivity of the reaction. Mechanistic studies, under an ethylene atmosphere, reveals that cationic complexes rearrange to neutral complexes, which are likely, the active species.
23

[en] CHARGE TRANSFER COMPLEXES WITH HIGH SURFACE AREA BASED ON TIO2 NANOPARTICLES MODIFIED WITH BIDENTATE LIGANDS: SYNTHESIS, CHARACTERIZATION AND PHOTOCATALYTIC ACTIVITY UNDER LOW-POWER VISIBLE LIGHT / [pt] COMPLEXOS DE TRANSFERÊNCIA DE CARGA COM ALTA ÁREA SUPERFICIAL BASEADOS EM TIO2 NANOMÉTRICO MODIFICADO COM LIGANTES BIDENTADOS: SÍNTESE, CARACTERIZAÇÃO E ATIVIDADE FOTOCATALÍTICA SOB LUZ VISÍVEL DE BAIXA POTÊNCIA

LUCAS ARAUJO LIMA ALMEIDA 21 November 2023 (has links)
[pt] Os nanomateriais à base de TiO2 sensíveis à luz visível estão entre as alternativas mais promissoras para aplicações fotocatalíticas, como remediação ambiental. Os complexos de transferência de carga (CTCs) entre nano-TiO2 e ligantes bidentados, uma alternativa, têm sido amplamente estudados. No entanto, a eficiência da fotodegradação e o papel das espécies oxidantes reativas (ROS) não são totalmente compreendidos. Além disso, o desenvolvimento de CTCs baseados em TiO2 modificado com ácido malônico (MoA) ainda não foi investigado, até onde é sabido. Neste estudo, CTCs de TiO2-Acetilacetona (ACAC) e TiO2-MoA com alta área superficial foram sintetizados via sol-gel. Ambos os CTCs à base de TiO2preparados foram submetidos a testes de fotodegradação de tetraciclina e clorofenolcom e sem sequestrantes de ROS sob luz visível de baixa potência (26 W). Os CTCs TiO2-MoA foram totalmente caracterizadas por análises de DRX, MS-TGA, FTIR, adsorção-dessorção de N2, DRS, PL, EPR e XPS. A síntese sol-gel e o processo de calcinação adotado produziram CTCs de anatásio fortemente ligados (ligação covalente) com acetilacetona e ácido malônico, capazes de absorver ao longo do espectro visível quando calcinados a 300 graus C (TiO2-A300) e 270 graus C (TiO2-MoA270). Ambos os CTCs calcinados apresentam um único elétron preso na vacância de oxigênio (SETOV / centro de cores F+). Os CTCs TiO2-MoA-270 apresentaram áreas superficiais (>306 m2.g-1), volumes de mesoporos (>0,339 mL.g-1) e atividadefotocatalítica extremamente elevados, degradando aproximadamente 100 por cento de TC após 6 h. Os CTCs TiO2-MoA-270 e TiO2-A300 são uma fonte eficiente de geração de radicais *O2- e ineficientes geradores de radicais OH*. Os resultados desta pesquisa podem ser aplicados à síntese, via sol-gel, de outros CTCs, como os ácidos dicarboxílicos, e explorados em estudos posteriores sobre purificação do ar e produção de hidrogênio. / [en] Visible light-sensitive TiO2-based nanomaterials are among the most promising alternatives for photocatalytic applications, such as environmental remediation. The charge transfer complexes (CTCs) between nano-TiO2 and bidentate ligands, an alternative, have been widely studied. However, the photodegradation efficiency and role of reactive oxidizing species (ROS) are not fully understood. In addition, the development of CTCs based on TiO2 modified with malonic acid (MoA) have not yet been investigated, as far as the authors know. In this study, TiO2-Acetylacetone (ACAC) and TiO2-MoA CTCs with high surface area were synthesized via sol-gel route. Both as-prepared TiO2-based CTCs were subjected to tetracycline and chlorophenol photocatalytic degradation tests with and without ROS scavengers under low-power visible light (26 W). The TiO2-MoA CTCs were fully characterized by XRPD, MS-TGA, FTIR, N2 adsorption-desorption, DRS, PL, EPR and XPS analysis. The sol-gel synthesis and the calcination process adopted produced CTCs of nano-TiO2 anatase strongly bond (covalent bond) with acetylacetone and malonic acid, capable of absorbing along the visible spectrum when calcined at 300 degrees C (TiO2-ACAC-300) and 270 degrees C (TiO2- MoA-270). Both calcined CTCs present single electron trapped in oxygen vacancy (SETOV / F +color center). The TiO2-MoA-270 CTCs showed very high surface areas (>306 m2.g-1), mesopore volumes (>0.339 mL.g-1) and the highest photocatalytic activity, degrading approximately 100 percent of the TC after 6 h. The TiO2-MoA-270 and TiO2-A300 CTCs were an efficient source of *O2- radicals and inefficient generation of OH* radicals. The findings of this research can be applied to the synthesis, via sol-gel, of other CTCs, such as dicarboxylic acids, and explored in further studies on air purification and hydrogen production.
24

Synthesis and Characterization of Copper Halide Complex Materials / Syntes och karakterisering av material baserade på kopparhalogenid-komplex

Tomita, Hiroki January 2021 (has links)
Energiförbrukning är ett hett ämne i världen idag, eftersom världens befolkning fortsätter att växa. Som ett resultat ökar också den globala energiförbrukningen snabbt och utsläppen av koldioxid därmed, vilket påverkar global uppvärmning och klimatförändringar. Således kommer utvecklingen av förnybara energikällor att bli en av nödvändighet. Solenergi utgör en förnybar energikälla och uppvisar en enorm potential för att tillgodose det globala energibehovet. En solcell är kan användas för att omvandla solljus till elektricitet. Många typer av solceller har utvecklats under det senaste decenniet, och forskning för att förbättra effektiviteten kommer att fortsätta i framtiden. Material baserade på kopparhalogenidkomplex har uppvisat intressanta optiska och elektrokemiska egenskaper på grund av flera laddningsöverföringsexciterade tillstånd. Genom att kombinera kopparhalogenidsystem med organiska ligander med två bindningsgrupper, kommer komplexet att kunna bilda nätverksstrukturer i flera dimensioner och därmed effektivt kunna leda ström. Eftersom kopparhalogenidkomplex uppvisar unika optiska och elektriska egenskaper, är det värt att undersöka dem för användning i solceller. Syftet med examensarbete har varit att undersöka kopparhalogenidkomplex med optiska och elektrokemiska egenskaper. Kopparhalogenidkomplex med bidentatligander har syntetiserats och applicera som tunna filmer undersöktes. I kapitel 1 och 2 av uppsatsen presenteras bakgrunden och en introduktion av denna studie, samt de experimentella metoderna. I kapitel 3 beskrivs syntesen av kopparjodid-4,4'-bipyridinkomplex och karakteriseringen av detsamma. Applicering av det resulterande materialet på glassubstrat diskuteras också. I kapitel 4 beskrivs syntesen av kopparhalogenid-N-oxid-4,4'-bipyridinkomplex med efterföljande karakterisering. I kapitel 5 undersöks metoder för att applicera kopparjodidpyridin på koppar-folie och FTO-belagda glassubstrat. / Energy consumption is presently a hot topic in the world since the world’s population continues to grow. As a result, global energy consumption is increasing rapidly and the emission of carbon dioxide is also increasing, which causes global warming and climate change. Thus, the development of renewable energy sources will be one of the solutions. Solar energy is one of the renewable energy sources and has a huge potential to satisfy the global energy demand. A solar cell harvests light and converts it to electricity. Many kinds of solar cells have been developed in the past decades, and investigation for the improvement of the efficiency will be continued in the future. Copper halide organic complex materials have some potential for optical and electrochemical properties due to several charge transfer states inside the structure. By combining copper halide with bidentate organic ligands, the complex will form high dimensional network structure and will have electrical property due to the formation of electron conducting paths. Since copper halide complex has potential for unique optical and electrical properties, it is worth investigating for the further photovoltaic application. The aim of the thesis is to investigate copper halide complex material showing optical and electrochemical property. Copper halide complex with bidentate ligands were synthesized and the way to apply copper halide complex to films were also investigated in this thesis. In chapter 1 and 2, the background and the introduction of this study and the experimental methods are presented. In chapter 3, the synthesis of copper iodide 4,4’-bipyridine complex and the characterization of the complex sample are presented. The application of the complex to glass substrate is also discussed. In chapter 4, the synthesis of copper halide N-oxide-4,4’-bipyridine complex and the characterization are discussed. In chapter 5, the way to apply copper iodide pyridine to copper foil and FTO-coated glass substrate is discussed.

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