Dans nos sociétés modernes, la santé et le bien-être des individus occupent une place de plus en plus grande, ce qui a conduit les chercheurs en marketing à s'intéresser aux problématiques liées à la promotion de la santé (Block et Keller, 1995; Cox et Cox, 2001; Keller et alii, 2003; Zhao et Pechman, 2007). Sur la base des recherches qui étudient les stratégies de communication susceptibles de provoquer le changement comportemental, ce travail doctoral cherche à répondre à la problématique suivante : comment améliorer l'efficacité des communications de santé ? Par le biais de deux expérimentations menées aux Etats-Unis entre 2009 et 2010, cette recherche étudie l'effet de deux caractéristiques du message, à savoir, le cadrage des conséquences du message (gains versus pertes) et l'objectif annoncé de la communication (prévention versus dépistage). Les résultats soulignent notamment qu'un cadrage de gains provoque une attitude plus favorable envers la recommandation, une intention plus élevée de la suivre ainsi que des intentions d'échanges et de recherche d'information plus élevées, ce qui est d'autant plus vrai lorsque l'objectif annoncé est celui du dépistage. Cette recherche apporte également une meilleure compréhension des mécanismes impliqués en montrant qu'un message de pertes provoque une imagerie mentale de valence plus négative et que la valence des images mentales est médiatrice de l'effet du cadrage. Ce travail doctoral donne lieu à des contributions théoriques, qui permettent d'éclairer la littérature sur les communications de santé, ainsi qu'à des contributions managériales, qui apportent des enseignements aux décideurs des communications de santé. / In our modern societies, individuals' health and well-being is a major concern which elicits marketing academics' interest to health promotion research questions (Block and Keller, 1995; Cox and Cox, 2001; Keller et alii, 2003; Zhao and Pechman, 2007). Based on research studying communication's strategies that could induce behavioral change, this doctoral work aims at answering the following research question: how to improve health communications effectiveness? Using two experiments conducted during 2009 and 2010 in the United-States, this research studies two message's characteristics, the message frame (gains versus losses) and the communication's promoted objective (prevention versus detection). Results highlight that a gain-framed message produces a more favorable attitude toward the recommendation, a higher intention to follow it and higher intentions to converse and to look for information, results that are even truer when communication's objective is detection. This research brings a better comprehension of depth processes involved, showing that a loss-framed message induces a valence of mental imagery which is more negative than a gain-framed message and that the valence of mental imagery mediates the effect of message framing. This doctoral work brings theoretical contributions, which add to health communications literature as well as managerial contributions, which bring learning to health communications managers.

Cette thèse a pour objet l'étude de 3 systèmes de fermions lourds à base d'Ytterbium, YbCu2Si2, YbCo2Zn20 et YbRh2Si2, dans des conditions extrêmes de hautes pressions, basses températures et hauts champs magnétiques. Une partie très importante dans ce travail a été le développement d'un dispositif de génération de force à très basses températures permettant une modulation de la pression in-situ adapté à des cellules à enclumes diamant. Pour YbCu2Si2, les mesures de ac-susceptibilité sous pression et sous champ magnétiques ainsi que les mesures d'aimantation sous pression montrent que l'ordre magnétique qui apparaît pour P> 8 GPa est ferromagnétique. L'étude du changement de la valence de l'ion Yb par des mesures de diffusion inélastique en conditions résonantes de rayons X ont permis de clarifier son interaction avec le magnétisme. Même si l'état trivalent est clairement favorisé sous pression, la valence reste inférieure à 3, proche de l'ordre magnétique, même dans les plus hautes pressions et plus basses températures. Nous avons également procédé à une recherche détaillée pour les signatures de metamagnétisme avec des mesures à très haut champ. Dans la deuxième partie de ma thèse, les mesures de ac-calorimétrie et ac-susceptibilité sous pression ont permit d'établir le diagramme de phase (P-T) dans YbCo2Zn20 jusqu'à 14 GPa. En plus, nos résultats suggèrent que l'ordre magnétique qui apparaît pour P>1 GPa est antiferromagnétique. Les forts effets du champ magnétique observées dans les propriétés physiques dans YbCo2Zn20 sont probablement liés à l'interaction entre le champ magnétique et les spins des électrons 4f et non à leur charge car la valence de l'Yb s'avère insensible à l'application d'un champ magnétique de 10 T. La partie finale de cette thèse est consacré à l'étude du diagramme de phase (H-T) sous pression dans YbRh2Si2 pour déterminer l'évolution de la température de l'ordre magnétique en fonctionne de H et P et mieux comprendre les effets liés à ce deux paramètres de contrôle. / In this thesis, three Yb-based heavy fermion compounds, YbCu2Si2, YbCo2Zn20 and YbRh2Si2, are studied under extreme conditions, i.e, high pressure, low temperatures and high magnetic fields. An important part of the work has been the set up of an in-situ tuning pressure device to measure diamond anvil cells at dilution fridge temperatures. This has enable most of the experimental results presented here. In YbCu2Si2 the nature of the pressure-induced magnetic order that arises for P> 8 GPa has been clarified to be ferromagnetic by ac-susceptibility and magnetization measurements under pressure. The interplay of magnetism and valence change has been investigated by measuring the valence of the title compound at high pressures and low temperatures using resonant inelastic x-ray scattering (RIXS). As expected, pressure favors the trivalent state but the Yb ion valence remains below 3 even at the highest pressure and at low temperatures very close to the onset of the magnetic order. We have also performed a detailed search for signatures of metamagnetism. The second part of my thesis focuses on YbCo2Zn20. We have extended the (P-T) phase diagram up to 14 GPa by ac-calorimetry and ac-susceptibility measurements. Our results shed some light on the nature of the magnetic order that arises for P>1 GPa which is antiferromangetic. The strong field effects observed in the physical properties in YbCo2Zn20 are probably related to the interaction between the magnetic field and the spin of the 4f electrons rather than to their charge as the valence of the Yb ion is insensitive to the application of a magnetic field of 10 T. The final part of this thesis is devoted to the detailed study of the (H-T) phase diagram under pressure in YbRh2Si2 to determine the evolution of the magnetic ordering temperatures as a function of H and P to better understand the interplay of the two control parameters.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho examina a forma como a noção clássica de valência é apropriada pelo currículo do Ensino Médio de Química, através da análise de vinte e sete livros didáticos novos e antigos. Os livros didáticos estão divididos em três categorias: Ensino Médio, Ensino Fundamental e Ensino Secundário. Com o objetivo de auxiliar a leitura dos livros didáticos no que se refere à apropriação da história do conceito, apresenta-se uma reconstrução racional da noção clássica de valência. O estabelecimento de um viés metodológico amparado na utilização de matrizes de precedência e de mapas conceituais, permitiu verificar que há prevalência na utilização de uma relação precedência específica, caracterizada como relação [A, P, L], a qual se refere aos temas: atomística, periodicidade química e ligações químicas. Essa relação de precedência constitui o chamado núcleo forte de uma estratégia didática, conforme endereçada pelos autores, para o aprendizado dos aspectos relacionados à estrutura da matéria. Um contraponto ao que é encontrado nos livros atuais é observado nos livros do antigo Ensino Secundário, nos quais não se observa a precedência [A, P, L]. Nesse sentido, considera-se o material do Chemical Bond Approach Committee CBA como uma forte influência para a implementação dessa precedência. No que se refere a uma aproximação mais ampla com a história da ciência, percebe-se que há preponderância de uso da história como eixo organizador na apresentação dos temas relacionados à mecânica quântica, mas que as relações históricas de precedência são, em geral, negligenciadas. Como alternativa a esse modo predominante de organização dos aspectos destinados à aprendizagem da estrutura da matéria, propõe-se a utilização de uma estratégia baseada na história da noção clássica de valência. / The study develops a framework for examining the way the classic notion of valency is adapted by the secondary teaching chemistry curricula. The analysis is based upon twenty-seven new and old textbooks. The textbooks are divided in three categories: new Secondary Teaching (ensino médio), new Primary Teaching (ensino fundamental) and old Secondary Teaching (ensino secundário). For aiding the analysis of the textbooks in how they appropriate the history of the concept it is presented a rational reconstruction of the classic notion of valency. The methodological approach uses precedence matrices and conceptual maps to verify the use of a specific precedence relationship, characterized as [A, P, L], which refers to the themes: atomistics, chemical periodicity and chemical bonding. This precedence relationship composes what is called the "hard nucleus" of the didactic strategy addressed by the authors for learning the themes related to the structure of matter. A counterpoint to what is found in the current books is observed in the books of the old Secondary Teaching, in which precedence [A, P, L] is not observed. In that sense, it is considered that the material of Chemical Bond Approach Committee CBA was a strong influence for the implementation of that precedence. It is also noticed that there is a prevalence of using the history as an organizing axis in the presentation of the themes related to the quantum mechanics, but that most textbooks lacked a history precedence and did not deal with the conceptual understanding. As an alternative way to the predominant organization observed it is proposed a strategy based in the history of the classic notion of valency.

Orientador: Rogério Custodio / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-18T08:56:05Z (GMT). No. of bitstreams: 1 Abreu_Leandrode_M.pdf: 3333566 bytes, checksum: 9df2fe3268e83e70fae31b792fc76513 (MD5) Previous issue date: 2011 / Resumo: Este trabalho avaliou o cálculo de energias de ionização verticais e as possibilidades de construção e interpretação de diagramas de correlação através do uso dos métodos Monte Carlo Quântico (MCQ) e Outer Valence Green¿s Function (OVGF). O trabalho foi dividido em quatro partes: Energias de ionização simples: Avaliou-se a capacidade dos métodos MCQ e OVGF em descrever os valores de energia de ionização de valência e de caroço e testou-se o uso de funções de onda relaxadas. A faixa dos desvios observados obtidas com o método Monte Carlo Quântico de Difusão (MCQD), em relação aos valores experimentais, é comparável a de outros métodos, como DFT (Teoria do Funcional de Densidade - Density Functional Theory) e CCGF (Funções de Green com Pares Acoplados - Coupled-Cluster Green¿s Function), 0,01 a 2 eV, e verificou-se que uso das funções de onda relaxadas é importante na descrição das ionizações de caroço. Energias de ionização sucessivas: Estimou-se as energias de ionização sucessivas dos elementos do 2º período a partir das energias orbitais do sistema neutro e comparou-se com resultados obtidos através dos métodos MCQ utilizando-se a função de onda do sistema não-ionizado. Pode-se demonstrar a falha das energias orbitais em descrever as energias de ionização sucessivas e obter correções com o uso dos métodos MCQ. Diagramas de correlação: Construíram-se diagramas de energia eletrônica total e de correlação quantitativos utilizando energia de ionização como binding energy para moléculas do tipo BAB (H2O e Li2O) através do uso dos métodos MCQ. Foram construídos diagramas de cargas parciais de Bader através das distribuições discretas de carga obtidas com os métodos MCQ para tentar interpretar os diagramas de correlação, porém a interpretação por comparação direta não foi possível, contudo foram obtidas informações importantes através dos diagramas de cargas parciais. Energias de dupla ionização: Foram calculadas energias de dupla ionização de sistemas atômicos e moleculares através do método OVGF e compararam-se os resultados obtidos com a Teoria do Funcional de Densidade (DFT). O método OVGF mostrou-se tão preciso quanto a teoria DFT na descrição das energias de dupla ionização / Abstract: The study was divided into 4 parts: Simple Ionization Energies: We evaluated the ability of MQC and OVGF methods in describing the values of the ionization energy of valence and core and tested the use of relaxed wave functions. The range of deviations obtained with the method of diffusion quantum Monte Carlo (MCQD), in relation to the experimental values, is comparable to other methods such as DFT (Density Functional Theory) and CCGF (Coupled-Cluster Green's Function), from 0.01 to 2 eV, and it was found that the use of the relaxed wave functions is important in the description of core ionizations. Successive Ionization Energies: We estimated the successive ionization energies of successive elements of the 2nd period from the orbital energies of the neutral system and compared with results obtained using the methods MCQ with the wave function of nonionized system. It can be shown the failure of the orbital energies to describe the successive ionization energies and to obtain corrections with the use of MCQ methods. Correlation Diagrams: Diagrams of total electronic energy and quantitative correlation diagrams were constructed using the ionization energy as binding energy for molecules of the type BAB (Li2O and H2O) through the use of MCQ methods. We constructed Bader¿s partial charges diagrams with the discrete charge distributions obtained with MCQ methods to try to interpret the correlation diagrams, but the interpretation by direct comparison was not possible, however, important information was obtained through diagrams of partial charges. Double Ionization Energies: We calculated double ionization energies of atomic and molecular systems by the OVGF method and compared the results obtained with the Density Functional Theory (DFT). The OVGF method proved to be as accurate as the DFT theory in describing the double ionization energies / Mestrado / Físico-Química / Mestre em Química

Dans le système YbMn6Ge6-xSnx, l’ytterbium de valence intermédiaire (v.i.) s’ordonne magnétiquement à des températures étonnamment élevées (jusqu’à TYb~125 K). Ce travail contribue à une meilleure compréhension des propriétés physiques de ces alliages grâce à la stabilisation de nouveaux composés dans la gamme de concentration 4,6<x<5,3. Des expériences extrêmement sensibles utilisant le rayonnement synchrotron (XANES, XMCD) ont permis de situer l’instabilité magnétique d’Yb vers x~5 ,2. Le diagramme de phase magnétique (x,T) a pu être complété. Il montre une étroite ressemblance avec le diagramme de Doniach. Dans les systèmes classiques à base d’Yb v.i., les propriétés physiques sont interprétées dans le cadre d’une compétition entre effet Kondo et interactions RKKY. La particularité du système YbMn6Ge6-xSnx est la présence d’un sous-réseau magnétique de Mn qui est très probablement à l’origine des propriétés singulières d’Yb : TYb élevées et existence de mYb jusqu’à des valeurs de valence plus basse qu’à l’accoutumée (u>~2,8). Des expériences sous pression ont souligné l’analogie entre les effets de pression mécanique et chimique. L’augmentation de pression favorise le caractère trivalent et le magnétisme d’Yb. La 2nde partie de ce travail constitue une ouverture vers les matériaux pour les applications magnétocaloriques haute température telles que les pompes à chaleur ou la conversion d’énergie. Elle concerne l’étude des composés Mn4-xFexGa2Sn et Fe3Sn2 qui possèdent des températures de travail supérieures à la température ambiante. Leur EMC est modéré mais comparable à celui d’autres matériaux à transition de 2nd ordre fonctionnant dans la même gamme de température / In the YbMn6Ge6-xSnx system, intermediate valent Yb magnetically orders at an astonishingly high temperature (up to TYb~125 K). This work aims to improve the understanding of the physical properties of these compounds, with an emphasis on the concentration range 4.6<x<5.3. Some results have been obtained thanks to highly sensitive experimental techniques using synchrotron radiation (XANES, XMCD), and allowed us to locate the Yb magnetic instability near x~5.2. The magnetic phase diagram (x,T) has been completed and shows some similarities with the Doniach diagram. In conventional intermediate valent Yb systems, there is a competition between the Kondo screening and the magnetic exchange interactions of RKKY-type. The particularity of YbMn6Ge6-xSnx compounds is related to the strong 3d Mn-5d Yb exchange interaction and to the nonzero exchange field at the Yb site generated by the magnetic Mn sublattice. It is most likely responsible of very unusual Yb magnetic properties, in particular the astonishingly high magnetic ordering temperatures of low valence Yb (u>~2,8). External pressure experiments showed an analogy between mechanical and chemical pressure effects. Increasing the pressure favors trivalent state and Yb magnetism. In a second part, we investigated the magnetic and magnetocaloric properties of Mn4-xFexGa2Sn and Fe3Sn2. High temperature magnetocaloric applications, such as heat pump or heat conversion, need materials with high Curie temperature. These two compounds have working temperatures above 330 K. The magnetocaloric effect has been evaluated : the magnitude is moderate but close to other compounds with a second order transition near this temperature region.

Les travaux présentés dans cette thèse s’inscrivent dans une thématique de modification de surfaces par le biais de monocouches auto-assemblées post-fonctionnalisables. L’objectif principal consiste à élaborer une méthode générique de modification de monocouches par des motifs moléculaires variés. Pour cela, les travaux se concentrent sur la mise au point d’une plateforme générique facilement fonctionnalisable par un motif d’intérêt et greffable sur électrode modifiée. La voie retenue consiste à utiliser deux réactions de "click chemistry" de type "CuAAC". La première réaction de CuAAC s’effectue en solution et permet de solidariser plateforme et motifs d’intérêt (principalement des dérivés ferrocényles). Les ligands ainsi obtenus ont été utilisés pour la complexation d’ions métalliques (Cu2+, Zn2+). Les ligands et les complexes ont été étudiés en solution par électrochimie ainsi que par spectroscopies UV-Visibles et RPE. La seconde réaction de CuAAC permet l’immobilisation des différents complexes de cuivre sur des électrodes pré-modifiées par des fonctions azoture, généralement à l’aide de monocouches auto-assemblées. Ce greffage s’effectue selon le mode opératoire de l’"électroclick auto-induite", c'est-à-dire que le complexe de cuivre à immobiliser est également catalyseur de la réaction de CuAAC. Les systèmes ainsi immobilisés (mono-, bi- ou tri-métalliques) ont pu être étudiés en terme de cinétique d’immobilisation, de cinétique de transfert d’électrons et en réactivité. Ce dernier point a par ailleurs fait l’objet d’une attention particulière pour le cas de la réduction électro-catalytique des ions nitrite par les complexes de cuivre (I), en solution et sur surface. / This work depends on functionalized surface theme using modification of selfassembled monolayers (SAMs). The main objective consists to elaborate a new general pathway to modify monolayers with miscellaneous objects of interest. For this, we decide to focus our work to synthesize a versatile platform handling two ethynyl arms. These functions are available to operate two CuAAC reactions. The first one is use for linking platform with object of interest (in general ferrocenyl derivatives). Ligands obtained by that way were used for complexation of Cu2+ and Zn2+ ions. Electrochemical and spectroscopic (UV-Visible and EPR) studies were performed on these compounds. The second CuAAC reaction is used to immobilize copper complexes on azide modified electrode (azide derivatives SAMs on gold and ITO or direct functionnalization of glassy carbon surface). The grafting is operating through “self-induced electroclick” method; this means the CuAAC reaction is catalysed by the copper complex which is immobilized. Functionalized electrodes were characterized by cyclic voltammetry. It appears that similar complexes have closed grafting kinetic. These studies also demonstrate the both influence of copper and spacer on a second electroactive site (ferrocene moieties). The reactivity of copper centre is evaluated for complexes in solution and immobilized on surface with electrocatalytic reduction of nitrite ions by copper (I) species. The catalytic efficiency strongly depends on potential of copper reduction. Also, similar complexes show a loss of catalytic power with immobilization on surface.

Au cours des dernières décennies, l'électronique s'est développée de manière à répondre au besoin grandissant de stocker et traiter toujours plus d'information, et elle a évolué de manière incessante vers une miniaturisation extrême. Dans ce contexte, les molécules-aimants, qui sont des entités moléculaires magnétiques, présentent une bistabilité magnétique permettant de stocker l'information dans des unités de la taille d'une molécule. Le principal frein aux applications tient aux basses températures auxquelles ces molécules présentent de telles propriétés (< 15K). Il est donc important de comprendre les mécanismes mis en jeu au sein de ces entités afin d'augmenter les températures de fonctionnement. Un moyen prometteur est de ponter deux ions de lanthanides par un ligand radicalaire. Cette approche a conduit à la conception de la molécule-aimant ayant à ce jour la plus haute température de blocage (14 K). Ce travail de thèse est dédié à la conception et à la caractérisation des structures, ainsi qu'à l'étude des propriétés magnétiques et des relations magnéto-structurales par spectroscopie électronique de molécules aimants et d'aimants à base moléculaires. Ces systèmes sont élaborés à partir d'ions de lanthanides(III) ou de manganèse(II) et de radicaux libres organiques de types nitronyl-nitroxyde. Une attention particulière sera dirigée vers la réalisation de complexes dinucléaires de lanthanides pontés par un ligand radicalaire, et sur l'étude de la brique monomérique. Nous avons exploré la possibilité d'utiliser le radical NITBzImH comme ligand radicalaire pontant des briques moléculaires de type [Ln(β- dicétone)3] et [Ln(NO3)3]. Nous nous sommes intéressés au comportement magnétique inhabituel d'un polymère de coordination de manganèse(II) pontés par les radicaux NITIm, parent de NITBzImH, puis nous avons commencé à nous intéresser à l'effet produit en remplaçant les manganèses(II) par des lanthanides(III) / For the past decades, electronics have been developed in order to meet the increasing need of information storage, always evolving to the constant upgrade of their components: better, faster, smaller. Twenty-five years ago, the recently created field of molecular magnetism allowed designing entities responding to the aforementioned requirements: Single- Molecule-Magnets (SMMs). On the one hand, those are compounds showing magnetic bistability affording to stock information and on the other hand, they are the smallest entities available to design any information support. In spite of those remarkable qualities, they require very low temperature (< 15 K) to display their properties. Thus, it is of primary importance to understand underlying mechanisms in order to increase this temperature range. One promising route is to connect lanthanide dimer by a radical bridge. This method has led to the discovery of a SMM, whose blocking temperature is the highest known to date (14 K). This thesis work has been dedicated to the conception of SMMs and molecular-based magnets, as well as the characterization of their structures and magnetic properties, and their magneto-structural relationships by electronic spectroscopy. Those systems were mostly based on lanthanide(III) or manganese(II) ion and nitronyl-nitroxide organic free radicals. A special focus was made to the synthesis of dinuclear lanthanide complexes bridged by an organic free radical, and to the study of their mononuclear complex. We have studied the potential of NITBzImH radical as a bridge for [Ln(β-diketonate)3] and [Ln(NO3)3] molecular bricks. We also took interest to the unusual magnetic behavior of a manganese(II) coordination polymer, where each metal center is bridged by a NITIm radical, closely related to NITBzImH radical. Finally, we started to explore the changes induced by switching manganese(II) to lanthanide(III)

Le sujet de la thèse concerne l’étude de l’inversion de valence dans des complexes FeIIFeIII induite par la déprotonation d’un ligand de FeII. L’intérêt de cette étude vient de ce que le processus considéré peut être décrit comme un transfert d’électron induit par un transfert de proton. Les transferts de protons et d’électrons sont au cœur de nombreuses réactions catalytiques ou biologiques et la compréhension des mécanismes de leur mise œuvre, séquentielle ou couplée, est un enjeu très actuel. La première partie de la thèse est consacrée à la caractérisation du premier système présentant cette propriété originale. Il est fondé sur un complexe binucléaire FeIIFeIII dont les deux ions Fe sont pontés par un dicarboxylate et un phénolate. Le FeIII est lié par un groupe bis-2-picolylamine et le FeII par un groupe similaire dans lequel une pyridine a été remplacée par une aniline. C’est la déprotonation de ce groupe aniline lié au FeII qui provoque l’inversion de valence, l’anilinate formé étant lié au FeIII. Le complexe aniline est isolé avec le groupe aniline en position -trans par rapport au phénolate pontant mais il possède la particularité de ne pas être stable en solution et de s’isomériser, le groupe aniline passant en position -cis par échange avec une pyridine. Le même phénomène est observé pour le complexe anilinate formé par déprotonation. Ce phénomène a été étudié en combinant les spectroscopies UV-visible, RMN du proton et Mössbauer et les caractéristiques thermodynamiques et cinétiques de l’isomérisation ont été déterminées. La relation entre le transfert d’électron et le transfert de proton a été étudiée par des techniques électrochimiques. Des études approfondies par cyclovoltamétrie et marquage isotopique ont montré que dans ce système les transferts d’électron et de proton sont concertés. La deuxième partie de la thèse est consacrée à l’étude des facteurs qui sont susceptibles d’influencer le transfert d’électron, c’est-à-dire les potentiels rédox des deux sites à Fe, et le transfert de proton, c’est-à-dire le pKa du ligand protique. Pour ce faire, de nouveaux complexes ont été préparés en modifiant soit le ligand protique, l’aniline étant remplacée par un benzimidazole, soit le groupe complexant le Fe, remplacement de la bis-2-picolylamine par la bis-(2-méthyl-N-méthylbenzimidazole)amine. Des complexes présentant ces modifications mais dépourvus du ligand acide ont été synthétisés pour étudier les effets de ces modifications sur les propriétés rédox des ions Fe. L’étude de l’influence des propriétés rédox a été menée dans un premier temps. La substitution du groupe complexant le FeIII n’a pas de conséquence importante au plan structural pour le complexe protoné qui existe toujours sous la forme de deux isomères. Par contre, après déprotonation un seul isomère existe. Les propriétés spectroscopiques sont peu altérées ce qui montre que la structure électronique du système n’est pas bouleversée. L’étude de l’influence des propriétés acides a été menée ensuite. Deux complexes ont été étudiés qui diffèrent par la nature du groupe complexant le FeIII. La substitution de l’aniline par le benzimidazole ne change pas de façon notable les propriétés structurales du système mais on note cependant que les valences des deux ions sont moins localisées. La déprotonation du benzimidazole est observée et conduit à un chromophore sensiblement différent du précédent illustrant les différences de ligand. L’étude électrochimique préliminaire révèle un comportement similaire au premier complexe étudié. / The thesis matter concerns the valence inversion in FeIIFeIII induced by deprotonation of a FeII ligand. This study is of strong interest owing to the fact this process can be described as an electron transfer induced by a proton transfer. Protons and electrons transfers play essential roles in numerous catalytic or biologic reactions and therefore understanding whether they occur in a sequential or concerted manner is presently a major endeavor. The first part of the thesis is devoted to the characterization of the first system possessing this original property. It is based on binuclear complex FeIIFeIII where the two Fe ions are bridged by a dicarboxylate and a phenoxide. The ferric ion is bound by a bis-2-picolylamine group and the ferrous ion by a similar group where a pyridine has been replaced by aniline. Deprotonation of this FeII bound aniline induces the valence inversion, the resulting anilide being bound to the FeIII ion. The aniline complex was isolated with the aniline in trans position with respect to the bridging phenoxide, but it is not stable in solution and isomerizes, the aniline group moving to a cis position upon exchange with a pyridine. The same phenomenon was observed for the anilide complex obtained through deprotonation. This phenomenon was studied by combining UV-visible, 1H-RMN and Mössbauer spectroscopies, and the thermodynamic and kinetic characteristics of the isomerization were determined. The link between the electron transfer and the proton transfer were studied by electrochemical techniques. Thorough studies by cyclic voltammetry and isotopic labeling showed that in this system the electron and proton transfers are concerted. The second section of the thesis was aimed at studying the factors susceptible to influence the electron transfer, namely the redox potentials of the two Fe sites, and the proton transfer, namely the pKa of the protic ligand. To achieve it, new complexes were prepared by modifying either the protic ligand, the aniline being replaced by a benzimidazole, or the Fe binding group, substitution of bis-2-picolylamine by bis-(2-methyl-N-methylbenzimidazole)amine. Model complexes incorporating these changes but deprived of the protic ligand were also obtained to assess their influence on the redox properties of the Fe ions. The study of the influence of redox properties was considered first. The substitution of the group complexing FeIII has not a strong influence on the structure of the protonated complex which still exists as two isomers. By contrast, after deprotonation a single isomer exists. The spectroscopic properties are mostly unchanged which shows that the electronic structure of the system is not altered significantly. The study of the influence of the acidicity was then conducted. Two complexes differing by the nature of the FeIII bound group were considered. Replacing aniline by benzimidazole does not change significantly the structural properties of the system, but the valences of the Fe ions are less localized than in the original complex. The deprotonation of benzimidazole occurs and leads to a chromophore that differs from the preceding, revealing the difference in ligands. However, a preliminary electrochemical study reveals a behavior similar to that of the original complex.

Phosphoryl transfers are essential chemical reactions in key life processes, including energy production, signal transduction and protein synthesis. They are known for having extremely low reaction rates in aqueous solution, reaching the scale of millions of years. In order to make life possible, enzymes that catalyse phosphoryl transfer, phosphoryl transferases, have evolved to be tremendously proficient catalysts, increasing reaction rates to the millisecond timescale. Due to the nature of the electronic structure of phosphorus atoms, understanding how hydrolysis of phosphate esters occurs is a complex task. Experimental studies on the hydrolysis of phosphate monoesters with acidic leaving groups suggest a concerted mechanism with a loose, metaphosphate-like transition state. Theoretical studies have suggested two possible concerted pathways, either with loose or tight transition state geometries, plus the possibility of a stepwise mechanism with the formation of a phosphorane intermediate. Different pathways were shown to be energetically preferable depending on the acidity of the leaving group. Here we performed computational studies to revisit how this mechanistic shift occurs along a series of aryl phosphate monoesters, suggesting possible factors leading to such change. The fact that distinct pathways can occur in solution could mean that the same is possible for an enzyme active site. We performed simulations on the catalytic activity of β-phosphoglucomutase, suggesting that it is possible for two mechanisms to occur at the same time for the phosphoryl transfer. Curiously, several phosphoryl transferases were shown to be able to catalyse not only phosphate ester hydrolysis, but also the cleavage of other compounds. We modeled the catalytic mechanism of two highly promiscuous members of the alkaline phosphatase superfamily. Our model reproduces key experimental observables and shows that these enzymes are electrostatically flexible, employing the same set of residues to enhance the rates of different reactions, with different electrostatic contributions per residue.

Narratives in the forms of music or literature have traditionally been highlightedfor their ability to evoke empathy; however, the specific features of the narrativethat serve as the underlying mechanisms responsible for this effect remain unclear.The aim of the present study was to examine the impact of a narrative’s style onempathy. An experimental repeated measures research design was used with 41participants (31 female, 10 male; age range 20-63 yrs, M=30.2 yrs) that underwentthree conditions each comprised of a different stimulus (i.e., a song, a piece ofprose and a poem), with the same narrative content but differing in style. The orderof the stimuli was randomized across participants. After each stimulus, empatheticresponses were captured via self reports, measuring valence and arousal of theparticipant, as well as their perceived valence and arousal of the main character ofthe narrative. The song had a strong correlation between participant-rating andcharacter-rating on valence and arousal, thus evoking a stronger (affective)empathetic response than the other two styles of stimuli, having moderatecorrelations. The character-rating barely differed between the style of stimuli, andthe narrative first presented lowered the participants’ valence regardless of style.These findings could possibly be explained by cognitive empathy responding to thenarrative, evoking the same understanding of another person, whereas affectiveempathy seem more prone to respond to stylistic features. Future research andpossible therapeutic implications are discussed. / Narrativ i form av musik och litteratur är kända för att kunna framkalla empati hos mottagaren; däremot är det fortfarande oklart vilka specifika aspekter av ett narrativ som ligger bakom denna effekt. Syftet med föreliggande studie var att undersöka effekten av narrativ stil på empati. En experimentell studie med inomgruppsdesign användes med 41 deltagare (31 kvinnor, 10 män, åldersintervall 20-63 år, M = 30.2 år) vilka exponerades för tre olika stimuli; en sång, en prosatext och en dikt. Varje stimuli hade samma narrativa innehåll men skilde sig åt beträffande narrativ stil. Presentationsordningen för stimulina randomiserades för deltagarna. Efter varje stimuli mättes empatisk reaktion via självskattningar av valens och arousal hos deltagarna, liksom hur de skattade valens och arousal för berättelsens huvudkaraktär. Sången visade en stark korrelation mellan deltagarnas självskattningar och skattningar av huvudkaraktären på både valens och arousal, vilket innebär att sången skapade ett starkare (affektivt) empatiskt gensvar än övriga två stimuli, vilka hade måttliga korrelationer. Skattningar av huvudkaraktärens valens och arousal påverkades ytterst lite av narrativ stil. Presentationsordningen påverkade deltagarnas skattningar då första stimulit sänkte deltagarnas valens oavsett narrativ stil. Dessa resultat kan eventuellt förklaras genom att kognitiv empati svarar på narrativets innehåll, att oavsett narrativ stil framkallas samma förståelse för en annan person, medan affektiv empati verkar påverkas utav den narrativa stilen. Framtida forskning och terapeutiska implikationer diskuteras.