Ce travail présente la synthèse et l’étude d’une nouvelle famille de composés photochromes de type di(hétéroaryl)éthène ainsi que leur utilisation comme ligand pontant en chimie de coordination dans le but d’élaborer des matériaux moléculaires à propriétés photomodulables. Depuis ces dernières années, le photochromisme occupe une place prépondérante dans le développement de nouveaux matériaux photosensible.Ainsi, de nouveaux di(hétéroaryl)éthènes, dérivés de terarylènes, ont été synthétisés et leurs propriétés photochromes ont été étudiées en détail. Ces nouveaux systèmes, baptisés tétrarylènes, ont également permis l’obtention de composés dissymétriques présentant un biphotochromisme exclusif. Enfin, ces tétrarylènes ont pu être utilisés pour la synthèse de complexes mono- et di-nucléaires de Cu(II). Certains cas ont alors révélé l’éjection réversible du métal de la cavité chélatante par étude RPE.Mots clés : photochromisme, diaryléthènes, terarylènes, commutation, Absorption transitoire, chimie de coordination, RPE / This work deals with the synthesis and study of a new family of photochromic di(heteroaryl)ethenes as well as their use as bridging ligand in coordination chemistry in order to design photo-switchable molecular materials. Over the past few years, the interest of the scientific world to photochromism is growing for its potential use in optical memory devices, optoelectronic or any others photonic devices.Thus, new di(heteroaryl)ethenes, structurally close from terarylenes, have been synthesized and their photochromic properties have been studied in depth. These new systems, called tetrarylènes, enable us to obtain biphotochromic compounds, introducing dissymmetry in the structure. Synthesis of mono- and di-nuclear copper(II) complexes can be performed using these tetrarylenes. Some cases revealed, by EPR study, the reversible release and uptake of the metal ion in solution upon irradiation.Key-words : photochromism, diarylethenes, terarylenes, switches, transitory absorption, Coordination chemistry, EPR

Cette thèse présente la dynamique ultrarapide de relaxation de molécules photochromes et des agrégats d'argon en phase gazeuse à l'échelle femtoseconde. Des expériences utilisant la technique « pompe-sonde » ont été menées sur un dispositif utilisant un faisceau moléculaire pulsé couplé à de l'imagerie de vitesse de photoélectron/photoion (VMI) et un spectromètre de masse à temps de vol (TOF-MS). Ces études nous ont permis de caractériser les changements de distribution électronique des différents systèmes en fonction du temps. Par ailleurs une étude théorie/expérience sur la caractérisation de la densité et de la distribution de vitesse au sein d'un faisceau moléculaire pulsé a aussi été réalisée. Dans le cas de la dynamique des dithienyléthènes, nous avons observé des mécanismes de relaxation électronique parallèles. Le paquet d'onde initial se sépare en deux parties distinctes. Une première partie se dirige vers l'état fondamental via une intersection conique, tandis que la deuxième partie reste quelques picosecondes dans l'état excité en oscillant avant de relaxer vers l'état fondamental. Cette étude nous a permis de comprendre la dynamique intrinsèque des différentes molécules étudiées, mais aussi d'étendre le mécanisme de relaxation à toute cette famille de molécules photochromes dans les trois phases dans lesquelles elles sont étudiées. Dans le cas des agrégats d'argon, deux phénomènes ont été observés à différentes échelles de temps. Le premier se produit dans les premières picosecondes et est la relaxation électronique d'un état excitonique à une vitesse d'environ 1 eV.ps⁻¹. Le deuxième phénomène résulte de la localisation de l'excitation sur une paire Ar₂* que nous avons pu observer à partir de 4-5 ps. L'éjection d'atomes d'argon excités a aussi été observée, nous permettant ainsi de connaitre la durée de vie maximale de l'état excitonique délocalisé. Ce travail a permis d'apporter des informations supplémentaires à celles fournies par les études réalisées en phase condensée. Il ouvre donc la voie vers l'étude de systèmes plus complexes tels que les nanoparticules en phase gazeuse. / This PhD thesis investigated the ultrafast dynamics of photochromic molecules and argon clusters in the gas phase at the femtosecond timescale. Pump-probe experiments are performed in a set-up which associates a versatile pulsed molecular beam coupled to a photoelectron/photoion velocity map imager (VMI) and a time-of-flight mass spectrometer (TOF-MS). Theses pump-probe experiments provides the temporal evolution of the electronic distribution for each system of interest. Besides, a modelization has been performed in order to characterize the density and the velocity distribution in the pulsed beam. Regarding the photochromic dithienylethene molecules, parallel electronic relaxation pathways were observed. This contrasts with the observation of sequential relaxation processes in most molecules studied so far. In the present case, the initial wavepacket splits in two parts. One part is driven to the ground state at the femtosecond time scale through a conical intersection, and the second part remains for ps in the excited state and experiences oscillations in a suspended well. This study has shed light into the intrinsic dynamics of the molecules under study and a general relaxation mechanism has been proposed, which applies to the whole family of dithienylethene molecules whatever the state of matter (gas phase or solution) in which they have been investigated. Concerning argon clusters excited at about 14 eV, two behaviors of different time scale have been observed at different time scales. The first one occurs in the first picoseconds of the dynamics. It corresponds to the electronic relaxation of an excitonic state at a rate of 1 eV.ps⁻¹. The second phenomenon corresponds to the localization of the exciton on the excimer Ar₂*. This phenomenon is observed 4-5 ps after the excitation. In this study, we also observed the ejection of excited argon atoms, addressing the lifetime of the delocalized excitonic state. This work provide additional informations compared to those contributed in condensed phase and it pave the way for new studies in gas phase on more complex system such as nanoparicles.

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As antocianinas compreendem o maior conjunto de pigmentos solúveis em água do reino vegetal. A absorção da luz por estes compostos, responsáveis pelas cores vermelha, azul e roxa da maioria das frutas e flores, é produto de combinações de vários fatores, como o número de substituintes, a presença ou não de outras moléculas capazes de estabilizar a cor (“co-pigmentos”), o pH local do meio e a natureza do microambiente em que a antocianina se encontra. A reatividade química e fotoquímica das antocianinas já é relativamente complexa em solução aquosa na ausência de micelas, onde cada um dos processos químicos e fotoquímicos ocorre numa faixa de tempo distinta. Uma forma de se diminuir o número de espécies em solução é o emprego de antocianinas sintéticas com estruturas simplificadas, conhecidas como sais de flavílio, cuja variação no número, posição e tipo químico de substituinte permite um certo controle sobre as frações molares das espécies. Neste estudo procurou-se compreender os processos que regem o equilíbrio ácido-base e a hidratação do cátion flavílio em ambiente micelar. Estes dois processos exercem um papel central na estabilização da cor em antocianinas. Foram utilizados três sais de flavílio: o 4-carboxi-7-hidroxi-4\'-metoxiflavílio (CHMF), o 2-fenilbenzopirílio e o 4\'-metoxiflavílio. Os dois grupos ionizáveis do CHMF possuem pKas distintos (pKa1 = 0,73; pKa2 = 4,84), cujas dinâmicas de protonação/desprotonação são influenciadas pelas micelas de SDS de modos diferentes. O cátion é estabilizado preferencialmente pelas micelas aniônicas em relação ao zwitterion (pKa1SDS = 2,77), que por sua vez é mais favorecido que a base quinonoidal (pKa2SDS = 5,64). A estabilização do cátion está relacionada com as fortes interações eletrostáticas entre a espécie e a micela carregada negativamente. A base quinonoidal, que no caso específico do CHMF tem carga negativa, é desfavorecida em relação ao zwitterion. Adicionalmente, em SDS praticamente não se observa hidrólise da espécie zwitteriônica. Com relação ao 2-fenilbenzopirílio (pKw = 3,01) e o 4\'-metoxiflavílio (pKw = 4,47), a primeira observação feita é que a inclusão do grupo metoxi na posição C4\' estabiliza o cátion flavílio, diminuindo a extensão da hidrólise por meio de transferência de carga para o anel central. O efeito de estabilização do cátion pelo ambiente micelar, verificado pelo aumento do pKw, é mais pronunciado no 2-fenilbenzopirílio (pKwSDS = 4,73) do que no 4\'-metoxiflavílio (pKwSDS = 5,05). Os processos cinéticos mostram que a reação de hidratação (kw) do flavílio sem substituintes diminui 65 vezes em SDS, enquanto que a reação no sentido inverso se mantém dentro da mesma ordem de magnitude. Já no caso do 4\'-metoxiflavílio, foi verificado que ambas as constantes de velocidade aumentam, mas a constante de desidratação do hemicetal (k-w), que depende da concentração de prótons, é a mais afetada, aumentando cerca de 15 vezes. Este fato é um indicativo de que o pH na interface micelar é o fator de estabilização do cátion do 4\'-metoxiflavílio. Adicionalmente foram feitos cálculos computacionais de transições eletrônicas, pKa e potenciais de redução em nível ab initio para um conjunto cátions flavílios e respectivas bases quinonoidais. Os valores de pKa calculados apresentaram um desvio médio de +/- 0,5 unidade de pKa. / Anthocyanins comprise the major water-soluble pigment group in the Plant Kingdom. Light absorption by these compounds is responsible for the diverse colors in many flowers and fruits and can be modulated by phenomena such as self-association of flavylium cations or anhydrobases, copigmentation with other polyphenols and flavonoids, complexation with metal ions, incorporation of anthocyanins into microaggregates like micelles and the pH of the medium. The chemical and photochemical reactivity of anthocyanins is quite complex in aqueous solution and each process occurs in a different time range. The use of structurally simplified synthetic flavylium salts permits a certain control over the mole fractions of the various species in solution. In this study we used the synthetic flavylium ions 4-carboxy-7-hydroxy-4\'-methoxyflavylium (CHMF), 2-phenylbenzopyrylium and 4´-methoxyflavylium to investigate the main processes that influence the acid-base equilibrium and hydration of the flavylium cation in micellar environments. Such reactions play a central role in color stabilization of anthocyanins. CHMF has two ionizable groups with distinct pKas (pKa1 = 0,73; pKa2 = 4,84), and the protonation/deprotonation dynamics of these groups are affected differently by SDS micelles. The results show that SDS micelles stabilize the cationic form rather than the zwitterion (pKa1SDS = 2,77), which is favored relative to the quinonoidal base (pKa2SDS = 5,64). The preferential stabilization of the cation is related to electrostatic interactions of this form with the anionic micelle. The quinonoidal base, which in the specific case of CHMF is an anion, is disfavored relative to the zwitterion. In addition, the hydrolysis of the zwitterionic form is substantially reduced in micellar SDS solutions. The comparison of 2-phenylbenzopyrylium (pKw = 3,01) and 4´-methoxyflavylium (pKw = 4,47) shows that the methoxy group at the C4´ position stabilizes the cationic form, reducing the hydration by charge transfer to the central ring. The stabilization of the cationic form by the micellar environment, which is reflected in the increase of the pKw, is more pronounced for the 2-phenylbenzopyrylium cation (pKwSDS = 4,73) than for 4´-methoxyflavylium (pKwSDS = 5,05). Kinetic studies of the 2-phenylbenzopyrylium ion in SDS indicate a 65-fold reduction in the hydration rate constant (kw), while the inverse reaction has the same magnitude as in water. In the case of the 4´-methoxyflavylium ion, both rate constants associated with the equilibrium between the flavylium cation and hemicetal increased. However, the [H+]-dependent rate constant for dehydration of the hemicetal is affected to a greater extent, increasing about 15 fold, indicating stabilization of the 4\'-methoxyflavylium cation by the micellar interface. Finally, computational calculations were performed at the ab initio level for several flavylium cations and anhydrobases to estimate the electronic transitions, pKa and reduction potentials. The quality of the calculated pKa results were compared with experimental data and the mean absolute deviation is +/- 0.5 pKa unit.

Filmes híbridos fotoativos de Ormosil (silicatos organicamente modificados) contendo o polioxometalato de Keggin ácido fosfotungstico (H3PW12O40) e cátions Ag+ foram preparados por meio da rota sol-gel e deposição de filme por dip-coating. A caracterização por FTIR, Raman, XRF e DRX evidenciou a formação da matriz de organossilicato e o aprisionamento dos poliânions PW12O403- e cátions Ag+. O comportamento fotocrômico dos filmes de Ormosil-fosfotungstato baseiam-se na redução fotoinduzida do fosfotungstato por exposição à radiação UV, o que leva à formação de compostos coloridos de valência mista conhecidos como heteropolyblues. No entanto, a presença de cátions Ag+ altera completamente o comportamento fotocrômico destes filmes híbridos. Os poliânions de fosfotungstato fotorreduzidos são agentes redutores eficientes na redução dos cátions Ag+, resultando na formação in situ de nanopartículas de prata metálica na matriz híbrida como evidenciado pela intensa banda plasmônica centrada em 390 nm no espectro eletrônico da amostra. A caracterização por Uv-vis e Espectroscopia de Absorção de Raios X próxima a Borda de Absorção (XANES) mostrou que a foto-redução pode ser revertida por tratamento térmico o que caracteriza um comportamento fotocrômico reversível. O comportamento cinético da amostra foi analisado propondo mecanismos para as reações de redução e oxidação da prata, responsáveis pela alteração de coloração do material. O aprisionamento de compostos fotoativos em matrizes híbridas orgânico-inorgânico via sol-gel é uma estratégia interessante para a preparação de materiais fotocrômicos com potenciais aplicações tecnológicas. A reversibilidade fotocrômica destes materiais os torna bons candidatos para aplicação em sistemas de memória óptica, filtros óticos de passa-banda estreita, dispositivos de ótica não linear, sensores de radiação UV e revestimentos bactericidas. / Sol gel entrapment of photoactive compounds in organic-inorganic hybrid matrices is an interesting strategy for the preparation of photochromic materials with potential technological applications. In this study, we report the preparation of photoactive Ormosil (organically modified silicates) hybrid films containing the Keggin polyoxometalate phosphotungstate (H3PW12O40) and Ag+ cations by sol-gel synthesis and dip coating deposition. The materials have been characterized by infrared absorption spectroscopy (FTIR), Raman spectroscopy and X-ray Fluorescence (XRF), thus evidencing the formation of hybrid organosilicate matrix and the entrapment of the PW12O40-3 polyanions and Ag+ cations. The photochromic behavior of the Ormosil-phosphotungstate films is based on photoinduced reduction of phosphotungstate upon exposure to UV radiation, which leads to the formation of colored mixed valence compounds known as heteropolyblues. However, the presence of Ag+ cations completely changes the photochromic behavior of these hybrid films. The photoreduced phosphotungstate polyanions rapidly promote the reduction of Ag+ cations, resulting in the in situ formation of silver metal nanoparticles (Ag0) inside the hybrid matrix as evidenced by the intense plasmonic band centered at 390nm as shown by electronic, UV-vis, spectroscopy and its yellowish color. The Uv-vis and X-ray Near Edge Absorption Spectroscopy (XANES) characterization shown that this process is reversible and the yellowish color characteristic of the metallic silver nanoparticles disappears once the hybrid films are heated at 353 K. Thus, the coloration is achieved upon UV exposure and discoloration occurs upon simple heating. Therefore, the described photoactive properties, the prepared hybrid films have potential application in optical memory systems, single bandpass optical filters, non-linear optical devices, UV radiation sensors and bactericidal coatings.

Textile UV-radiation sensors has lately been introduced to the field of smart textiles. Inkjet printing has been used as means of application due to the effective and resource efficient process. UV-LED radiation curing has been used in combination with inkjet printing in favour of low energy requirements, solvent free solution and reduced risk of clogging in the print heads. The problems arising when exposing photochromic prints to UV-radiations are that oxygen inhibition during the curing and photo-oxidation in the print reduces the prints ability to develop colour. It is the oxygen in the air in combination with UV-radiation that gives the photo-oxidating behavior. The aim of the study is to with the aid of physical protection reduce the effect of oxygen inhibition and photo-oxidation in the prints. Three types of physical treatments were used, wax coating, protein based impregnation and starch based impregnation. Treatments were applied before curing as well as after curing and the colour development after activation during 1 min of UV-radiation was measured with a spectrophotometer. Multiple activations were also tested to see how the treatments affected the fatigue behaviour of the prints over time. The aim was to have as high colour development as possible reflecting reduced oxygen inhibition and photo-oxidation. Results showed significantly higher colour development for samples treated with wax and whey powder before curing, but reduced colour development for amylose impregnation. Over time whey powder before curing showed highest colour development due to highest initial colour development. Lowest fatigue was seen for washed samples containing the chemical stabiliser HALS, showing an increased colour development. In reference to earlier studies the protective properties of wax and whey powder is due to their oxygen barrier properties protecting the print. The tested treatments have shown that it is possible to reduce the effect of photo-oxidation during curing leading to prints giving higher colour development. This gives a great stand point when improving existing and future application of photochromic prints on textiles.

Basé sur les concepts de développement durable et de chimie verte, l’une des alternatives envisagées par les chimistes, pour une chimie plus propre, est de substituer les solvants organiques, pouvant être dangereux et toxiques, par des solvants plus verts. L’eau est un bon candidat pour cette substitution car c’est le solvant le moins cher dans nos contrées, et le plus sûr : il est non-toxique, ininflammable et non explosif. Afin de palier la faible solubilité de la majeure partie des composés organiques dans l’eau, les tensioactifs peuven têtre utilisés afin d’améliorer les rendements réactionnels. Les milieux ainsi obtenus sont difficilement recyclables car ils nécessitent une forte dilution afin de casser les agrégats et de récupérer les produits. C’est pourquoi, l’utilisation de tensioactifs photo-régulables est une bonne alternative car il est possible d’organiser/désorganiser les agrégats par irradiation lumineuse et ainsi récupérer les composés organiques en fin de réaction tout en recyclant le milieu réactionnel. Pour cela, nous avons synthétisé trois tensioactifs possédant une fonction azobenzène(anionique, cationique, non ionique), afin de les tester en catalyse micellaire. Certains de ces tensioactifs, après en avoir déterminé leurs propriétés physico-chimiques (cmc et spectre UV-Visible) ont été testés dans une réaction pallado-catalysée : la substitution allylique de Tsuji-Trost. Nous avons réussi à démontrer l’intérêt d’utiliser un tensioactif photo-régulable par rapport aux tensioactifs commerciaux en terme de rendement et de recyclabilité. D’autre part, la décarboxylation de Barton, décrite pour la première fois en 1983, permet la formation d’alcanes à partir d’acides carboxyliques en utilisant un dérivé d’étain comme donneur d’hydrogène. Depuis lors, cette réaction a toujours été utilisée comme étape clé en synthèse totale de composés naturels et en solvants organiques. De plus, cette réaction est historiquement réalisée par activation conventionnelle, thermique ou par irradiation ultra-violette. C’est pourquoi, nous avons décidé d’étudier cette décarboxylation radicalaire dans l’eau, en présence de tensioactifs et en utilisant des modes d’activation non conventionnels : les micro-ondes et les ultrasons. De plus, en lieu et place d’étain, nous avons préféré l’utilisation de N-phénylmaléimide, déjà connu et étudié comme piège à radicaux, afin d’obtenir des maléimides substitués par des chaînes carbonées. Les rendements obtenus en milieux micellaires se sont avérés être aussi bons, voire meilleurs qu’en solvants organiques. / Based on concepts of sustainable development and green chemistry, one of the alternatives envisioned by chemists is to substitute organic solvents, which can be dangerous and toxic, for greener solvents. Water is the best candidate for this substitution because it is thesafest and cheapest solvent in our countries : this solvent is non-toxic, non-flammable and inexplosive. In order to overcome the low solubility of most of organic compounds in water, surfactants can be used to improve the reaction yields. Media thus obtained are difficult to recycle because they require high dilution in order to break aggregates and recover products. Therefore, using photo-switchable surfactants is a good alternative because they can organize/disorganize by light irradiation. Organic compounds could be recovered after reactions and the recyclability of the medium can be improved. For this purpose, we synthesized three surfactants having an azobenzene moiety (anionic,cationic, nonionic), to test them in micellar catalysis. Some of these surfactants, after determining their physicochemical properties (CMCs and UV-visible spectra) were studied in a pallado-catalyzed reaction, the allylic substitution of Tsuji-Trost. We have successfully demonstrated the value of using a photo-switchable surfactant compared to commercialones in terms of yields and recyclability. In other hand, Barton decarboxylation, described for the first time in 1983, permits the formation of alkanes from carboxylic acids, using tin derivatives as hydrogen donors. Since then, this reaction has always been used as a key step in total synthesis of natural compounds in organic solvents. In addition, historically, this reaction was carried out by conventional activation (heat or ultraviolet light). Therefore, we decided to study this radical decarboxylation in water, in the presence of surfactants and using unconventional activation modes : microwave and ultrasound. Moreover, instead of tin, we preferred the use of N-phenylmaleimide, already known and studied as a radical trap, to obtain maleimides substituted by carbon chains. Yields obtained in micellar media were found tobe at least as good as in organic solvents.

This thesis is focused on the photochromic molecule of spiropyran, which changes its structure as well as physical and chemical properties after UV irradiation. These changes are reversible, the molecule thermally restore its initial structure. For the study, the molecule SP1 with the systematic name 1',3'-dihydro-1',3',3'-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-(2H)-indole] was used. This molecule was incorporated within polymers PVK, Tg PPV, PCBTDPP and PCDTBT and the method of UV-VIS spectroscopy was used to observe the photochromic activity within these matrices. The influence of matrices to the ability to undergo UV induced photochromic conversion as well as to the reverse conversion to the initial structure induced by heat was monitored. Furthermore, the influence of spiropyran to the electrical properties of individual matrices was studied. The effect of photochromic conversion to both, the mobility of charge carriers and to the photogeneration was observed. For this purpose, the method of current-voltage measurement was used.

In this project, I investigate the photoconductivenature of photochromic rare-earth metal oxy hydrides (REMHO). Such materials have received increasingscientific attention since they show a color-neutralphotochromic effect that can be applied, e.g., in smartwindows or chromogenic devices. Photochromicmaterials reversibly turn opaque from transparentunder illumination with light of optical wavelength. Inrecent studies it was found that these materials alsoshow an instant decrease in resistivity whenilluminated which can be used in optical sensors. Tounderstand the nature of this photoconductive effect,I grew yttrium oxy hydride thin films by reactivemagnetron sputtering. I measured the resistivity forillumination from front and substrate side, opticaltransmission and compositions of the samples andrelated the results to photoconductivity. I show thatphotoconductivity is a bulk effect and not directlyrelated to photochromism. Samples that almost lostphotochromism due to aging, still show strongphotoconductivity. Moreover, it was observed that theresistance increased faster during bleaching for frontillumination than for back illumination.