This thesis describes the design, synthesis and reactivity of bimetallic complexes of doubly-pillared Schiff-base calixpyrrole ligands. Chapter One introduces the oxygen reduction reaction in light of the global energy scenario at present and in the future. Compounds and materials known to catalyse this reaction are discussed, with particular focus on transition metal complexes of pyrrole-containing macrocycles and the ability of these compounds to act as catalysts in redox reactions. Chapter Two describes the design and synthesis of several of the macrocyclic ligands developed during this project. The wide range of metals and geometries supported by one of the ligands, H4L, are outlined and include complexes of alkali-metals (Li, K), a rare earth metal (Mg), transition metals (Pd, Fe) and an actinide (UO2 2+). Chapter Three presents the use of [Co2(L)] for the reduction of dioxygen to water. The redox behaviour of the complex and its ability to reversibly bind oxygen were evaluated. The catalytic activity of [Co2(L)] was investigated in solution by UV-Vis spectrophotometry and electrochemically by rotating ring-disk electrochemistry. In Chapter Four, the ability of [Zn2(L)] to bind anions is described. Isothermal microcalorimetry, NMR, UV-Visible spectrophotometry, and fluorophotometry were used to study the de-aggregation of the anion free complex and the subsequent anion binding event. The stability of the complexes was estimated by DFT calculations. Chapter Five outlines the synthesis of complexes of L for other transition metals relevant to small molecule activation. Chapter Six contains a conclusion and suggestions on further investigations to carry out. Chapter Seven presents the full experimental details and analytical data for this work.

The correlation between NMR chemical shifts of interstitial atoms and electronic structures of boron- and carbon-centered hexazirconium halide clusters was investigated by density functional theory (DFT) calculation. The influences of bridging halide and terminal ligand variations on electronic structure were examined respectively. Inverse proportionality was found between the chemical shifts and the calculated energy gaps between two Kohn-Sham orbitals of t1u symmetry, which arose from the bonding and antibonding interaction between the zirconium cage bonding orbitals and the interstitial 2p orbitals. Chemical shielding properties of the interstitial atoms were calculated with Gauge Including Atomic Orbital (GIAO) method. Stepwise ligand substitution of terminal chlorides on [(Zr6CCl12)Cl6]4-cluster by tri(n-butyl)-phosphine oxide (Bu3PO) was conducted with the aid of TlPF6. Composition of the reaction mixtures was analyzed by use of both 13C and 31P NMR. A preliminary scheme for synthesis and separation of [(Zr6CCl12)Cl6-x(Bu3PO)x]x-4 (x = 3 ?? 5) mixture based on solubility difference was reevaluated. Three 1,10-phenanthroline based bidentate ligands, namely, 2,9-Bis(diphenyl-phosphinyl)-1,10-phenanthroline, 2,9-Bis(diethoxyphosphoryl)-1,10-phenanthroline, and 2,9-Bis(di-n-butoxyphosphoryl)-1,10-phenantholine, were synthesized for bridge-chelating the hexazirconium clusters. Coordination chemistry of these ligands with the [Zr6BCl12] and [Zr6CCl12] clusters was subject to preliminary investigation.

The correlation between NMR chemical shifts of interstitial atoms and electronic structures of boron- and carbon-centered hexazirconium halide clusters was investigated by density functional theory (DFT) calculation. The influences of bridging halide and terminal ligand variations on electronic structure were examined respectively. Inverse proportionality was found between the chemical shifts and the calculated energy gaps between two Kohn-Sham orbitals of t1u symmetry, which arose from the bonding and antibonding interaction between the zirconium cage bonding orbitals and the interstitial 2p orbitals. Chemical shielding properties of the interstitial atoms were calculated with Gauge Including Atomic Orbital (GIAO) method. Stepwise ligand substitution of terminal chlorides on [(Zr6CCl12)Cl6]4-cluster by tri(n-butyl)-phosphine oxide (Bu3PO) was conducted with the aid of TlPF6. Composition of the reaction mixtures was analyzed by use of both 13C and 31P NMR. A preliminary scheme for synthesis and separation of [(Zr6CCl12)Cl6-x(Bu3PO)x]x-4 (x = 3 ?? 5) mixture based on solubility difference was reevaluated. Three 1,10-phenanthroline based bidentate ligands, namely, 2,9-Bis(diphenyl-phosphinyl)-1,10-phenanthroline, 2,9-Bis(diethoxyphosphoryl)-1,10-phenanthroline, and 2,9-Bis(di-n-butoxyphosphoryl)-1,10-phenantholine, were synthesized for bridge-chelating the hexazirconium clusters. Coordination chemistry of these ligands with the [Zr6BCl12] and [Zr6CCl12] clusters was subject to preliminary investigation.

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No description available.

Durant ma thèse, j'ai recherché les conditions pour l'activation / fonctionnalisation de liaisons C-H pour la construction de bi(hétéro)aryles tolérant des groupement fonctionnels réactifs tels que des silyles, des alcènes, des esters ou encore des amides. Par rapport aux protocoles de couplage classiques tels que les réactions de Suzuki, Stille ou Negishi, la fonctionalisation de liaisons C-H fournit des procédures moins coûteuses et plus écologiques si elle tolère des groupements utiles en synthèse. D'abord, nous avons observé que les thiophènes substitués par des silyles en C2 peuvent être arylés avec des bromures d'aryle sans désilylation en présence du précatalyseur Pd(OAc)2/dppb. Les produits de couplage sont obtenus avec de bons rendements et avec inhibition de la réaction de désilylation. Ensuite, nous avons démontré que le système Pd(OAc)2/KOAc sans ligand phosphine, favorise l'arylation directe des hétéroaromatiques et inhibe la réaction de type Heck avec des thiophenes substitués par des alcènes substituées sur les carbones 2 ou 3. Ensuite, nous avons démontré que les fonctions esters sur les hétéroaromatiques peuvent être avantageusement utilisées comme groupements protecteurs, permettant l'arylation directe d'hétéroaromatiques sur le carbone C5. Enfin, l'heteroarylation directe de 2- ou 4-bromobenzamides avec des hétéroarènes catalysée au palladium a été étudiée. En présence de KOAc comme base, aucune formation de liaisons C-C ou C-N par couplage de deux bromobenzamides n'a été observée. / During my thesis, I focused on condition for the activation / functionalisation of C-H bonds for the construction of biaryl derivatives tolerant to the reactive functional groups such as silyl, alkenes, esters or amides. Compared to classic cross-coupling protocols (Suzuki, Stille or Negishi), C-H bond functionalisation provides a costly effective and environmentally attractive procedures. At first, we observed that the silyl-substituted thiophenes can be directly arylated with aryl bromides without desilylation, using the simple Pd(OAc)2/dppb precatalyst for both conversion and desilylation inhibition. Then, we have demonstrated that the Pd(OAc)2/KOAc catalyst system without phosphine ligand, even using as few as 0.1 mol% of Pd catalyst, promotes the direct arylation of heteroaromatics and inhibits the Heck type reaction with 1,2-disubstituted alkenes. In addition, we demonstrated that easily accessible esters on heteroaromatics can be advantageously employed as blocking groups in the course of the direct arylation of several heteroaromatic derivatives. Finally, the palladium-catalyzed direct heteroarylation of 2- or 4-bromobenzamide with heteroarenes was studied. In the presence of KOAc as the base, no formation of C-N or C-C bonds by coupling of two bromobenzamide was observed.

Advanced nanomaterials show a significant improvement in certain physical or functional properties compared to conventional materials. Such advanced materials are, for example, lead halide perovskites (LHP). It is a group of hybrid organic-inorganic materials with a direct bandgap exhibiting unique optical properties. The high quantum efficiency of photoluminescence makes nanocrystals or thin films of LHP suitable candidates for the production of light-emitting diodes, solar cells and LCD displays. Their inexpensive and simple fabrication together with their unique optical properties makes LHP one of the most developed materials of the last decade. This diploma thesis aims to study the optical properties of CsPbBr3 perovskite nanocrystals using high lateral resolution methods. CsPbBr3 perovskite nanocrystals show intense anti-Stokes photoluminescence. These nanocrystals can emit light with a lower wavelength than that of the light that causes their photoluminescence. The nanocrystals are prepared in two different ways: by evaporation or by crystallization of the precursor in a solution of dimethylformamide. The morphology, photoluminescence properties and chemical composition of individual nanocrystals are studied. Each nanocrystal is studied individually and its size, shape, photoluminescence properties and chemical compounds are determined, which leads to a deeper understanding of the anti-Stokes photoluminescence of perovskite nanocrystals.

Le premier projet de ce travail de doctorat a consisté à étudier l’activité catalytique de complexes à base de gallium(I), pour continuer à rechercher des alternatives aux catalyseurs à base de métaux nobles, plus communs, mais réputés coûteux et/ou toxiques. Le savoir-faire de l’équipe en catalyse par des complexes de gallium(III) a pu être réinvesti dans l’étude de ce bas degré d’oxydation du gallium, rarement étudié dans la littérature scientifique, dans l’espoir de détecter des réactivités et/ou sélectivités différentes d’avec des complexes de gallium(III). Ainsi, le complexe cationique bien défini de gallium(I) [Ga(PhF)2][Al(OC(CF3)3)4] a été employé dans une large gamme de réactions dans lesquelles les catalyseurs à base de gallium(III) avaient déjà fait leurs preuves, telles que l’hydroarylation d’arénynes, la réaction de Friedel-Crafts ou encore l’hydrogénation d’alcènes par transfert, pour laquelle une réactivité supérieure à celle des complexes usuellement utilisés au sein de l’équipe a été observée. Un analogue à base d’indium(I), [In(PhF)2][Al(OC(CF3)3)4], a également été étudié dans ces réactions, sans succès. En revanche, il s’est avéré efficace dans le cadre de réactions d’hydroamination d’aminoalcènes.En parallèle a été conduit un projet basé sur l’étude en tant qu’abstracteurs d’halogénures de complexes de divers métaux (argent, lithium, potassium, thallium(I)) comportant l’anion perfluoré, très volumineux et très faiblement coordinant [Al(OC(CF3)3)4]-. Dans le cadre de l’activation de pré-catalyseurs à base d’or(I), de gallium(III) ou d’indium(III) par abstraction d’halogénures, les sels d’argent sont les plus communément employés dans la littérature. Cependant, ces sels d’argents ne sont pas innocents en termes de réactivité. Par ailleurs, si les cations métalliques des sels employés en abstraction d’halogénures font l’objet d’un nombre raisonnable d’études dans la littérature, ce n’est pas autant le cas des anions qui leur sont associés : notre étude s’oriente selon ces deux problématiques. Il s’est avéré que les propriétés très faiblement coordinantes de l’anion [Al(OC(CF3)3)4]- ont mené à des réactivités et sélectivités différentes de celles obtenues avec l’emploi de sels plus usuels, AgSbF6 plus particulièrement, dans le cadre de réaction classiquement catalysées par l’or(I) ou le gallium(III) et déjà étudiées dans le premier projet de ce travail de thèse. Les complexes à base de gallium(I) et d’indium(I) impliqués dans le premier projet ont également été, succinctement, étudiés dans ce projet parallèle. / In the main project of this thesis work, the catalytic activity of gallium(I)-based complexes was explored. The aim was to keep on looking for alternatives to noble metals-based, more common catalysts, which have a reputation for being expensive and/or toxic. The know-how developed in the team on gallium(III)-based catalysis was reinvested into the study of this low oxidation degree of gallium, only scarcely studied in the literature. It was hoped to then detect different reactivity and/or selectivity than with gallium(III) complexes. Thus, the well-defined, cationic, gallium(I)-based complex [Ga(PhF)2][Al(OC(CF3)3)4] was used in a large array of reactions that were already successfully studied with gallium(III)-based catalysts, such as the hydroarylation of arenynes, the Friedel-Crafts reaction or the transfer hydrogenation of alkenes. In this later reaction in particular, the observed reactivity was superior to that achieved with the catalysts more commonly used in the team. An indium(I)-based analogue, [In(PhF)2][Al(OC(CF3)3)4], was also tested in these reactions, without any success. However, it was actually efficient in the context of aminoalkenes hydroamination reactions.The side-project of this work consisted in the study as halide abstractors of complexes, based on diverse metals (silver, lithium, potassium, thallium(I)) and containing the perfluorinated, very bulky and very weakly coordinating anion (WCA) [Al(OC(CF3)3)4]-. In the frame of the activation of gold(I), gallium(III) or even indium(III)-based pre-catalysts by halide abstraction, silver salts are the most frequently used. However, these silver salts are not non-innocent in terms of reactivity. Besides, if the cationic metal of the salts used in halide abstraction are the subject of a reasonable amount of studies in the literature, it is not the case of their anionic counterparts: we planned to address these two problematics with this project. It appeared that the very weakly coordinating properties of the anion [Al(OC(CF3)3)4]- in the context of the previously referred to reactions classically catalyzed by gold(I) or gallium(III)-based complexes led to different reactivity and selectivity than those achieved with the usual salts and in particular AgSbF6. The gallium(I) and indium(I)-based complexes involved into the main project were also briefly studied in this side-project.

<p>Over the last two decades, an increasing number of highway construction and maintenance projects in the United States have been completed at night to avoid or mitigate traffic congestion delays. Working at night entails several advantages, including lower traffic volumes at night, reduced impact on local businesses, more freedom for lane closures, longer possible work hours, lower pollution, cooler temperatures for equipment and material, and fewer overall crashes due to lower traffic volumes at night. Although nighttime roadway operations may minimize traffic disruptions, there are several safety concerns for motorists passing by and for workers in the nighttime work zone. For instance, just in 2019, there were 842 work zone fatalities reported in the United States, with 48% of these being associated with fatalities on night shifts. Additionally, 70% of these fatalities involved drivers/occupants under the age of 50. Moreover, improper lighting arrangements or excessive lighting levels produced by temporary lighting systems installed at the job site could cause harmful levels of glare for the traveling public and workers leading to an increase level of hazards and crashes in the vicinity of the work zone. </p> <p>To address the issue of glare, very few studies have been conducted to evaluate and quantify glare at work zones. Most of these studies were limited to the determination of disability glare levels of lighting systems (balloon lights and light towers) with a metal-halide type light source by using the veiling luminance ratio (<em>VL ratio</em>) as a criterion for limiting disability glare. However, deeper evaluation of the effects of driver’s age on the veiling luminance ratio, and the use of energy-efficient lighting systems which employ light-emitting diode (LED) type light sources were not performed.</p> <p>This thesis focuses on determining and evaluating disability glare on nighttime work zones as a step towards developing appropriate lighting strategies for improving the safety of workers and motorists during nighttime highway construction and maintenance projects. Disability glare is the glare that impairs our vision of objects without necessarily causing discomfort and it can be evaluated using the veiling luminance ratio (<em>VL ratio</em>). In this study, disability glare values were determined by using lighting data (vertical illuminance and pavement luminance measurements) from testing 49 lighting arrangements. Two LED balloon lights, a metal-halide light tower, and an LED light tower were utilized for the field lighting experiments. The disability glare level evaluation examines the effects of mounting height, power output, rotation angle, and aiming angle of luminaires on the veiling luminance ratio values (which is a criterion for limiting disability glare). </p> <p>The analysis of the disability glare values revealed four major findings regarding the roles played by the mounting height, power output, lighting system orientation, aiming angles of luminaries, and driver’s age on disability glare levels as follows: (i) an increase in mounting heights of both balloon lights and light towers resulted in lower veiling luminance ratio values (or disability glare); (ii) compared to the "perpendicular" and "away" orientations, orienting the light towers in a "towards" direction (45 degrees) significantly increases the disability glare levels of the lighting arrangement; (iii) increasing the tilt angles of luminaires of the portable light towers resulted in an increase in veiling luminance ratio values; (iv) for balloon lights, at observers ages over 50, <em>VL ratio</em> values were found to be greater than the maximum recommended; (v) for LED light towers oriented towards the traffic, at driver’s ages over 40, <em>VL ratio</em> values exceed the Illuminating Engineering Society (IES) recommended value; and (vi) for metal-halide light towers oriented towards the traffic, at driver’s ages over 50, <em>VL ratio</em> values exceed the IES recommended value. The results from this research study can provide State Transportation Agencies (STAs) and roadway contractors with a means to improve glare control strategies for nighttime work.</p>

No description available.