Ligands bidentes en chimie de l'or : de la stabilisation d'espèces réactives à la catalyse

Cette thèse porte sur l'étude de complexes définis d'or, de la stabilisation de composés originaux à leur utilisation pour de nouvelles transformations. Une approche conjointe expérience/théorie a été employée. De nouveaux complexes d'or ont été synthétisés et caractérisés par différentes techniques spectroscopiques et de diffractométrie. Leurs réactivités, notamment dans des procédés catalytiques, ont été étudiées. Les calculs DFT ont aiguillé le choix des ligands/complexes d'intérêts. Ils ont permis d'analyser la structure électronique des nouvelles espèces isolées et d'élucider les mécanismes mis en jeu. Une vue d'ensemble de l'utilisation de ligands bidentes pour la chimie de l'or montrant leurs implications dans le développement de cette chimie est présenté dans le premier chapitre. Une comparaison des différents ligands bidentes accessibles rationnalise le choix de deux d'entre eux pour les études présentées par la suite. Le second chapitre concerne le développement de la réaction d'hétéroarylation des alcènes catalysée par le complexe MeDalPhosAuCl. Cette nouvelle transformation procède via un cycle catalytique Au^I/Au^III et combine addition oxydante et activation PI à l'or. Un mécanisme détaillé est proposé sur la base d'analyses RMN in situ, d'étude par marquage au deutérium et de calculs DFT. La réaction a pu être généralisée à un large panel de substrats et un changement inhabituel de régiosélectivité a été observé pour les alcènes internes cis ou trans. Le troisième chapitre est dédié à l'isolation et la caractérisation des premiers complexes d'or impliquant des liaisons hydrogènes Au···H-X. Grâce aux ligands hémilabiles (P,N), un contact proche entre l'or et l'hydrogène a été observé par DRX et la présence de la liaison hydrogène N-H···Au a été démontrée sans ambiguïté par spectroscopies RMN et IR. La nature de cette liaison a été méticuleusement analysée par calcul DFT fournissant des arguments en faveur d'une liaison hydrogène, interaction attractive non-covalente. Une étude in silico sur de nouveaux modèles, avec des interactions Au···H-X potentielles (X = N, O ou P, variations des ligands ou de l'encombrement stérique) a été réalisée pour donner des directives aux futurs travaux expérimentaux. Le quatrième chapitre porte sur l'étude de carbènes alpha-CF_3 d'or(I). L'intérêt est double : 1) très peu de carbènes alpha-CF_3 ont été isolés et caractérisés et 2) beaucoup de molécules bioactives ou de matériaux possèdent des substituants CF_3 augmentant l'intérêt pour les réactions de trifluorométhylation. Grâce au ligand bis-phosphine o-carborane, plusieurs carbènes alpha-CF_3 d'or(I) ont été synthétisés, isolés et complètement caractérisés par spectroscopie RMN multi nucléaire, DRX et spectrométrie de masse. La liaison M=C_carbène a été analysée par calculs DFT avec une attention particulière pour la description des orbitales moléculaires et la contribution relative donation/rétrodonation entre le fragment métallique et le carbène. La réactivité de ces nouveaux carbènes d'or vis-à-vis de réactions d'insertion et de cyclopropanation a été étudiée montrant que ces espèces imitent les carbènes alpha-CF_3 transitoires postulés pour d'autres métaux de transition.The present work deals with the study of defined gold complexes from the stabilization of original compounds to their use for novel transformations. A joint experimental/theoretical approach has been used. New gold complexes were synthesized and characterized by different spectroscopic means and diffractometry. Their reactivities notably in catalytic process were studied. DFT calculations guided for the choice of ligands/complexes of interest. They helped to analyze the electronic bonding of the new isolated species and to elucidate the involved mechanism. An overview of the use of bidentate ligand in gold chemistry showing their involvement in the expansion of this field is presented in the first chapter. A comparison of the different bidentate ligands available rationalize the choice of two of them for the following studies. The second chapter concerns the development of hetero-arylation reaction of alkenes catalyzed by the MeDalPhosAuCl complex. This new transformation proceeds via Au^I/Au^III catalytic cycle and merge oxidative addition and PI-activation at gold. A detail mechanism is suggested based on in situ NMR analyses, deuterium labelling studies and DFT calculations. The scope of the reaction has been explored for a large number of substrates and an unusual switch of regioselectivity was observed for internal alkenes cis or trans. The third chapter is dedicated to the isolation and characterization of the first gold complexes involving Au···H-X hydrogen bonding. Taking advantage of the hemilabile (P,N) ligands, a close contact between gold and hydrogen was observed by XRD and the presence of N-H···Au hydrogen bond was unambiguously demonstrated by NMR and IR spectroscopies. The nature of this bonding was thoroughly analyzed by DFT providing compelling evidence for noncovalent attractive hydrogen-type bonding. An in silico study on new models, with potential Au···H-X interaction (X = N, O or P, ligand and steric hindrance modulation) have been performed to provide guidelines for further synthetic work. The fourth chapter focused on the study of alpha-CF_3 gold(I) carbene complexes. The interest is twofold: 1) very few alpha-CF_3 carbene complexes have been isolated and characterized and 2) many bioactive molecules or materials bear CF_3 substituents, increasing the interest for trifluoromethylation reactions. Taking advantage of the o-carborane diphosphine ligand, several alpha-CF_3 gold carbene complexes were synthesized, isolated and fully characterized, at low temperature, by means of multinuclear NMR spectroscopy, XRD and mass spectrometry. The M=C_carbene bonding situation was analyzed carefully by DFT calculations with particular attention to the description of molecular orbitals and to the relative donation/retrodonation contribution between the metallic fragment and the carbene. The reactivity of this new gold carbene towards insertion reaction and cyclopropanation was studied showing that they mimic transient alpha-CF_3 metal carbene complexes

Possibilities of obtaining selected non-ferrous metals by recycling of metal-bearing wastes.

Tato bakalářská práce je zaměřena na problematiku možnosti získání vybraných neželezných kovů cestou recyklace kovonosných odpadů. Věnuje se schématickému roztřídění odpadních materiálů a také rozdělení odpadu s obsahem neželezných kovů. Obsahuje vybrané metody pro zpracování kovonosných odpadů a charakteristiku tří vybraných neželezných kovů – mědi, olova a zinku. Součástí práce je také praktická část, ve které jsou zdokumentovány možnosti využití hydrometalurgických metod zpracování vybraných kovonosných odpadů, a získání majoritních kovů procesem cementace. Praktická část byla realizována v laboratořích, kterými je vybavena katedra Neželezných kovů, rafinace a recyklace na Vysoké škole báňské – Technické univerzitě v Ostravě.This bachelor thesis focuses on the problematics of obtaining non-ferrous metals through recycling metal-containing waste. It schematically sorts waste materials and includes clasification of waste containing non-ferrous metals. The thesis also shows different metalworking methods used for processing metal-containing waste and the characteristics of three selected basic non-ferrous metals - copper, lead and zinc. There is also a practical part of the thesis that documents possibilities of using hydrometallurgical methods to process some kinds of metal-containing waste materials and therefore obtaining major metal through cementation process. The practical part took place at university laboratories provided by the department of non-ferrous metals, refining and recycling.637 - Katedra neželezných kovů, rafinace a recyklacevýborn

The Warburg and Crabtree effects: On the origin of cancer cell energy metabolism and of yeast glucose repression

AbstractDuring the last decades a considerable amount of research has been focused on cancer. Recently, tumor cell metabolism has been considered as a possible target for cancer therapy. It is widely accepted that tumors display enhanced glycolytic activity and impaired oxidative phosphorylation (Warburg effect). Therefore, it seems reasonable that disruption of glycolysis might be a promising candidate for specific anti-cancer therapy. Nevertheless, the concept of aerobic glycolysis as the paradigm of tumor cell metabolism has been challenged, as some tumor cells exhibit high rates of oxidative phosphorylation. Mitochondrial physiology in cancer cells is linked to the Warburg effect. Besides, its central role in apoptosis makes this organelle a promising “dual hit target” to selectively eliminate tumor cells. From a metabolic point of view, the fermenting yeast Saccharomyces cerevisiae and tumor cells share several features. In this paper we will review these common metabolic properties as well as the possible origins of the Crabtree and Warburg effects. This article is part of a Special Issue entitled: Bioenergetics of Cancer

THE USE OF PHYSIOLOGICAL PARAMETERS IN MEASURING THE VEGETATIVES CONSEQUENCES OF MENTAL IMAGERY

INTRODUCTION The effects of the mental repetition of an activity entail not only the improvement of motor performances, but create vegetative consequences, which are connected to the degree of imagined effort (Decety, Jeannerod, Germain et Pastene, 1991 ). These beneficial effects of imagery have been explained by considering that the central structures of programming allow the anticipation of the metabolic requirement according to the established goals. The authors who do not agree on the explanatory theory of vegetative changes observed during the mental imagery phase, also have differing opinions concerning the existence of measurable muscular activity. Traditional instruments of measure such as heart rate and electromyography were used as well as force measurement. The force allowed us to know the, mechanical force produced, which should be zero during imagery phase not to have a conclusion in favor of a mechanical action. METHODS If we consider, with Jagasinski and Nicholls (1984,1987) that the central structure involved in the programming of a real activity, as in an imagined activity, defines the contents of this activity according to a goal, we can then assume that the mental operations occuring before the beginning of an action affect the level of effort and the energetic or metabolic resources used. We asked 24 male subjects who had obtained good results at the Sheehan imagery questionnaire to imagine a precise isometric contraction : bending the elbow. Through the use of instructions, one group of 8 subjects had to complete the task (called the goal of implication in a task), 8 other subjects had to do better than the others, surpass them (ego implication goal) while the 8 remaining subjects were given no instructions to achieve the goal. All the subjects went through two sessions including positive\negative feed-backs. In the real execution phase as well as in the imaginary phase, the measurements of heart rate and the electromyography of the biceps brachi and the force used are the primary indicators concerning the vegetative changes. RESULTS They show no trace of electromyography activity during the imagined movement if we make sure of the absence of movement during this phase by using a force transducer. Besides, there is a significant rise in the heart rate, during a real movement as well as an imagined one and this is even more evident when the subjects go from the conditions of implication in a task and implication of ego. At the same time, the subjects stated that they made less effort when they were given a positive feed-back and made higher levels of effort when they received a negative feed-back in an implication of ego situation. DISCUSSION In the mental imagery phase, all significant muscular activity is due to a mechanical action. In the absence of force production, even with the creation of an image, the muscle produces no activity. The potential of a subliminal muscular activity would be the real action in weak proportions but mechanically not significant for the chosen movement. The benefits of the mental repetition are here considered according to a symbolic perspective. and emphasize the cognitive components of the mental repetition, in other words, the individual imagined the activity to be accomplished. This is a matter of purely cognitive process. If a muscular activity is visible, the individual has gone from the stage of an intention of movement to his effective achievement, this change would come from the representation of the activity that the subject creates himself. We may conclude that measurements made with biomechanical devices can be very useful to check psychological hypotheses in sport. REFERENCES 1-BERGUS ; JONES, E.E. : Drug choice as self handicapping strategy in response to no contingent success. Journal of personnality and social psychology 76 : 14E158.1978. 2-CARVER, C.S ; SCHEIER. M F. : Attention and self regulation. A confrol theory approach lo human behavior. New York : Sp~nger- Verlag. 1981 3JAGASINSK1, C.D.; NICHOLLS. J.G. : Concepttons of a Ability and Related in Task lnvolment and Ego Involrnanl. Journal of Educational Psychology 76 : 909-919. 198

The story of Zarafa, the giraffe of king Charles X

In 1826, the Mamluk Pasha of Egypt, Muhammad-Ali, offered a giraffe to King Charles X of France. It was the first time that a live giraffe came to France. The transport of an animal of such dimensions turned into an incredible story. In 1824, the young giraffe was captured in southern Sudan, transported overland on the back of a camel, then in a boat across the Mediterranean. In 1827, she started a long walk that lasted 41 days from Marseille to Paris, under the personal supervision of Etienne Geoffroy Saint-Hilaire, a well-known French naturalist from the Royal Museum of Natural History. The giraffe caused a sensation wherever she went. In Paris, 600,000 visitors came to see her in the zoo of the Royal Museum of Natural History during the summer of 1827, creating a fashion craze referred to as giraffomania. This saga produced abundant memorabilia, which is still available today. This giraffe lived quietly for 18 years in the zoo. After her death, she was nicknamed Zarafa, the Arabic word for giraffe.En 1826, le Pacha d'Egypte, Méhémet-Ali offrit une girafe au roi de France, Charles X. C'était la première fois qu'une girafe vivante venait en France. Le transport d'un animal de cette envergure fut une incroyable épopée. En 1824, la jeune girafe fut capturée dans le sud du Soudan, transportée d'abord à dos de dromadaire, ensuite par bateau pour traverser la Méditerranée. En 1827, la girafe entama une longue marche de 41 jours de Marseille à Paris, sous la surveillance personnelle d'Etienne Geoffroy Saint-Hilaire, éminent naturaliste français du Muséum Royal d'Histoire Naturelle. Elle produisit un enthousiasme partout où elle passa, jusqu'à Paris où 600000 visiteurs vinrent la voir à la Ménagerie durant l'été 1827. En France, on parla de girafomania. Aujourd'hui, de nombreuses traces de cette épopée perdurent. La girafe vécut 18 ans à la Ménagerie. Longtemps après sa mort, elle fut surnommée Zarafa, le mot d'origine arabe signifiant girafe

Bidimensional lamellar assembly by coordination of peptidic homopolymers to platinum nanoparticles

A key challenge for designing hybrid materials is the development of chemical tools to control the organization of inorganic nanoobjects at low scales, from mesoscopic (~µm) to nanometric (~nm). So far, the most efficient strategy to align assemblies of nanoparticles consists in a bottom-up approach by decorating block copolymer lamellae with nanoobjects. This well accomplished procedure is nonetheless limited by the thermodynamic constraints that govern copolymer assembly, the entropy of mixing as described by the Flory–Huggins solution theory supplemented by the critical influence of the volume fraction of the block components. Here we show that a completely different approach can lead to tunable 2D lamellar organization of nanoparticles with homopolymers only, on condition that few elementary rules are respected: 1) the polymer spontaneously allows a structural preorganization, 2) the polymer owns functional groups that interact with the nanoparticle surface, 3) the nanoparticles show a surface accessible for coordination

Processing of metal waste-sludge from the galvanizing plants

This paper deals with the possibility of obtaining zinc from waste galvanic sludge, which is formed during galvanic plating. The aim of the experimental and practical part was to obtain zinc after the leaching of galvanic sludge. Leaching was performed in sulfuric acid, nitric acid and hydrochloric acid at different temperatures and time intervals with the addition of oxidizing agents as hydrogen peroxide or ozone. A separation of the leach and filtrate using filtration followed. The leach was further processed by a precipitation of iron and other metals using various agents. After a further filtration, the electrolysis was performed in order to obtain pure zinc on the cathode at the electrical voltage of approximately 3.5 V. Leaching using a solution of sodium hydroxide or potassium hydroxide was also performed when the prior dissolving of a major part of zinc into the leach occurred, while iron and non-ferrous metals remained in the leaching residue. After the filtration of the leach, the electrolysis with a high zinc yield of a purity of more than 99% followed. This way seems to be an optimal one for building a semi-industrial line for galvanic sludge recycling. All the partial products, i.e., the leach, the leaching residue, the filtrate, the solid precipitate and the separated metal on the cathode were subjected to chemical analyses. The analyses results are presented in tables and graphs.Web of Science1211art. no. 194

Spin crossover in Fe(triazole)–Pt nanoparticle self-assembly structured at the sub-5 nm scale

A main goal of molecular electronics is to relate the performance of devices to the structure and electronic state of molecules. Among the variety of possibilities that organic, organometallic and coordination chemistries offer to tune the energy levels of molecular components, spin crossover phenomenon is a perfect candidate for elaboration of molecular switches. The reorganization of the electronic state population of the molecules associated to the spin crossover can indeed lead to a significant change in conductivity. However, molecular spin crossover is very sensitive to the environment and can disappear once the molecules are integrated into devices. Here, we show that the association of ultra-small 1.2 nm platinum nanoparticles with FeII triazole-based spin crossover coordination polymers leads to self-assemblies, extremely well organized at the sub-3 nm scale. The quasi-perfect alignment of nanoparticles observed by transmission electron microscopy, in addition to specific signature in infrared spectroscopy, demonstrates the coordination of the long-chain molecules with the nanoparticles. Spin crossover is confirmed in such assemblies by X-ray absorption spectroscopic measurements and shows unambiguous characteristics both in magnetic and charge transport measurements. Coordinating polymers are therefore ideal candidates for the elaboration of robust, well-organized, hybrid self-assemblies with metallic nanoparticles, while maintaining sensitive functional properties, such as spin crossover