15 research outputs found
Synthesis of Al doped ZnO nanoparticles by aqueous coprecipitation
International audienceAl-doped ZnO particles were obtained by a simple route: soda addition in aqueous cationic solution. The effects of temperature, hydrolysis duration, reagent concentration and time were investigated. A non-topotactic reaction mechanism, involving firstly the precipitation of various hydroxide compounds depending on the route (low or high pH), followed by the dissolution-recrystallization of the hydroxide species into ZnO was demonstrated. The Al concentration in the final ZnO nanopowders did not exceed 0.3 at.% which correspond to the solubility limit of Al in ZnO. The different experimental conditions allow the morphology of ZnO particles to be controlled from isotropic nanoparticles of several tens of nanometers, platelets of several hundreds of nanometers or agglomerates of needle like particles
Assemblages moléculaires photoactifs pour la limitation optique et la bio-imagerie
Dans cette thĂšse, nous ciblons de nouveaux absorbeurs biphotoniques pour la bio-imagerie et la limitation optique. Nous nous sommes intĂ©ressĂ©s plus prĂ©cisĂ©ment Ă des octupĂŽles, structures connues pour possĂ©der des propriĂ©tĂ©s intĂ©ressantes en optique non-linĂ©aire et plus particuliĂšrement en absorption Ă deux photons. Ainsi, les cĆurs isocyanurate et 1,3,5-triazine, connus comme Ă©tant des accepteurs, mĂšnent Ă des octupĂŽles bidimensionnels lorsquâils sont substituĂ©s de façon symĂ©trique. Pour lors, les isocyanurates ont Ă©tĂ© peu Ă©tudiĂ©s pour lâoptique non linĂ©aire tandis que les triazines ont dĂ©jĂ Ă©tĂ© Ă©tudiĂ©es dans ce cadre et sont connues pour avoir de bonnes propriĂ©tĂ©s en absorption Ă deux photons. Dans un premier temps, nous nous sommes intĂ©ressĂ©s Ă la synthĂšse dâisocyanurates organiques et Ă lâĂ©tude de leurs propriĂ©tĂ©s optiques. Nous avons plus particuliĂšrement Ă©tudiĂ© lâeffet de la planarisation et de lâextension du systĂšme conjuguĂ©. Dans un deuxiĂšme temps, nous nous sommes intĂ©ressĂ©s Ă la synthĂšse et Ă lâĂ©tude des propriĂ©tĂ©s optiques des tristyryltriazines afin de comparer celles-ci Ă leurs analogues tristyrylisocyanurates et dâĂ©tudier lâinfluence du cĆur sur les propriĂ©tĂ©s en sachant que la triazine est un cĆur plus Ă©lectroattracteur que lâisocyanurate. Puis, nous nous sommes intĂ©ressĂ©s Ă la synthĂšse de complexes ruthĂ©nium-alkynyl trinuclĂ©aires Ă cĆurs isocyanurates et triazines, car le ruthĂ©nium est un mĂ©tal d6 connu pour amĂ©liorer les propriĂ©tĂ©s en optique non linĂ©aire. Enfin, nous avons synthĂ©tisĂ© des dĂ©rivĂ©s hydrosolubles de composĂ©s organiques qui prĂ©sentaient les propriĂ©tĂ©s optiques les plus prometteuses pour la bio-imagerie. En collaboration avec le Dr. Gary-Bobo, nous avons pu confirmer le potentiel de ces molĂ©cules pour de telles applications.In this work, new biphotonic absorbers were targeted for applications in bio-imaging and optical limiting. We have investigated the synthesis of octupoles since these multipolar structures were often shown to lead to interesting optical properties, especially two-photon absorption. The structures studied were isocyanurate- or 1,3,5-triazine-cored star-shaped derivatives. Both cores are known to be electron-accepting units and to give rise to two-dimensional octupoles when symmetrically substituted. So far, isocyanurates have not often been studied in nonlinear optics, whereas triazines have already been screened and were shown to have good two-photon absorption properties. We first focused on the synthesis of organic isocyanurates and on the study of their optical properties. We started by studying the planarization effect of the extension of the peripheral arms on the optical properties. We then focused on the synthesis and study tristyryltriazines analogous to the previous tristyrylisocyanurates. New structure/property relationships were thus established since the triazine is more electron-attracting than the isocyanurate core. We next synthesized ruthenium-alkynyl trinuclear complexes with isocyanurate and triazine cores, since ruthenium is a d6 metal known to enhance the nonlinear optical properties. We finally studied water-soluble derivatives for bio-imaging. In collaboration with Dr. Gary-Bobo we confirmed their potential for such applications
Préparation du motif RCF2R par Fluoration Radicalaire
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Préparation du motif RCF2R par Fluoration Radicalaire
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Preparation of ArCF2CH2N Motif by Radical Azidation/Fluorination Sequence
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Radical Amidoâ and AzidoâFluorination of αâFluorostyrene Derivatives: An Innovative Approach Towards ÎČâArylâÎČ,ÎČâdifluoroamino Motifs
International audienceAn innovative one-step synthesis towards ÎČ-aryl-ÎČ,ÎČ-difluorocarbamates and ÎČ-aryl-ÎČ,ÎČ-difluoroazides is presented. The described approach relies on the use of α-fluorostyrene substrates in a radical addition/fluorination reaction with N-centered radicals in the presence of SelectfluorÂź. The best results were obtained for the azidofluorination reaction. The resultant ÎČ-arylÎČ,ÎČ-difluoroazides were further transformed into Nitrogenbased heterocycles (e. g. pyrrole, triazole, and tetrazole) and in more elaborated azide derivatives
Preparation of ArCF2CH2N Motif by Radical Azidation/Fluorination Sequence
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