Les espaceurs auto-immolables sont des assemblages moléculaires inactifs permettant de découpler deux entités chimiques A (un groupe protecteur subissant une activation) et B (un composé d'intérêt, tel qu'un principe actif, un rapporteur ou un autre espaceur) par des liaisons covalentes. Sous l'effet d'un stimulus externe (activation), A est clivé spontanément lors d'un processus irréversible appelé auto-immolation, qui provoque la libération de l'espèce B. Cette dernière est généralement inactive lorsqu'elle est intégrée dans l'espaceur ; en revanche, une fois libérée, elle retrouve son activité intrinsèque.La cinétique du processus d'auto-immolation contrôle la corrélation spatio-temporelle existant entre l'activation et la libération de la substance active. L'objectif principal de ce travail a été précisément de fournir un ensemble complet de données permettant d'établir des relations structure/propriétés cinétiques fiables dans une série d'espaceur auto-immolable contenant une structure aromatique portant un substituant hydroxyle et s'appuyant sur un mécanisme impliquant une cascade électronique. Ainsi, nous avons utilisé un groupe photactivable et la lumière pour déclencher le processus d'auto-immolation d'une grande banque d'espaceurs auto-immolables, qui présentent un temps caractéristique d'auto-immolation s'étalant sur un large éventail d'échelle de temps (10-4-104s).Au cours de ce travail, nous avons également développé des espaceurs auto-immolables, qui libérent deux composés après activation. Ces systèmes ont été mis en ¿uvre pour répondre à l'analyse quantitative d'un substrat libéré par photodéprotection dans les systèmes biologiques. / Self-immolative spacers are inactive molecular assemblies decoupling two chemical entities A (a protecting group undergoing activation) and B (a compound of interest such as a drug, a reporter or another spacer) via covalent bonds. Under the effect of an external stimulus (activation), A is cleaved thus spontaneously initiating an irreversible process called self-immolation, which ultimately causes the release of the species B. The latter is usually inactive by binding on the spacer but, once released, it recovers its intrinsic activity. The kinetics of the self-immolation process controls the spatiotemporal correlation existing between activation and release of the active compound. Although many kinetic studies have been already reported on various series of self-immolative spacers, literature still lacked homogeneous information permitting comparative analysis of the kinetics of self-immolation. The major aim of this work was precisely to provide an extensive set of data drawing reliable structure property relationships in a series of self-immolative spacers containing an aromatic structure bearing a hydroxyl substituent and relying on a mechanism involving an electronic cascade. Thus we used a photactivable group and light to trigger the disassembly process of a large collection of self-immolative spacers, which exhibit self-immolation time varying over a wide range of time scale (10-4-104s). During this work, we also developed self-immolative spacers, which could release two compounds after a single activation. These systems have been implemented to address the quantitative analysis of a substrate released by uncaging in biological systems.

Adsorption on solid surfaces from solution is a fundamental property of a surfactant. It might even be the most important aspect of surfactant behavior, since it influences many applications, such as cleaning, detergency, dispersion, separation, flotation, and lubrication. Consequently, fundamental investigations of surfactant adsorption are relevant to many areas. The main aim of this thesis has been to elucidate the adsorption properties, primarily on the solid/water interface, of a particular class of polyhydroxyl based surfactants: the alkyl glucosides. By the use of ellipsometry, the equilibrium and kinetic aspects of adsorption on titanium dioxide with respect to structural effects has been studied. Furthermore, the effects of small amounts of cationic surfactant additives on the adsorption on silica have been investigated. The results have been compared with similar studies for other nonionic surfactants. We have found that the surfactant structure has a strong effect on the adsorption properties. An increase in the surfactant chain length increases the cooperativity of the system. An increase in the head group polymerization decreases the cooperativity and the plateau adsorbed amount at equilibrium. The effect of surfactant structure on the adsorption kinetics depends on the concentration relative to the cmc, while the there is a decrease in the rate of desorption with increasing hydrophobic chain length independent of the concentration. The adsorption/desorption process is concluded to be diffusion driven, as suggested by the model used. When comparing these results with studies on ethylene oxide based surfactants, we conclude that the two types of surfactants exhibit similar trends on surfaces onto which they adsorb. Adsorption from binary surfactant solutions is even more interesting than adsorption from single surfactant solutions, since it brings us one step closer to the systems used in applications. In addition, adsorption from a mixture can be very different from adsorption from any of the single surfactants in the mixture. Alkyl glucosides alone do not adsorb on silica, but addition of small amounts of a cationic surfactant to the alkyl glucoside solution allows for adsorption on silica. A comparison between the adsorption and bulk properties has shown that mixed micellization explains most, but not all, effects of the coadsorption properties. Changing the pH in the mixed systems reveals that a surfactant with a pH-dependent charge and the ability to adapt its charge to the environment, e.g. a surface, enhances the adsorbed amount over a wider range of pH values than a purely cationic surfactant. It is well known that alkyl glucosides and ethylene oxides adsorb differently on different types of hydrophilic surfaces. As a consequence, replacing ethylene oxides with alkyl glucosides might not be all straight-forward; however, we have shown that the effect of the surface can be eliminated by the use of a cosurfactant. / <p>QC 20101018</p>

<p>Adsorption on solid surfaces from solution is a fundamental property of a surfactant. It might even be the most important aspect of surfactant behavior, since it influences many applications, such as cleaning, detergency, dispersion, separation, flotation, and lubrication. Consequently, fundamental investigations of surfactant adsorption are relevant to many areas.</p><p>The main aim of this thesis has been to elucidate the adsorption properties, primarily on the solid/water interface, of a particular class of polyhydroxyl based surfactants: the alkyl glucosides. By the use of ellipsometry, the equilibrium and kinetic aspects of adsorption on titanium dioxide with respect to structural effects has been studied. Furthermore, the effects of small amounts of cationic surfactant additives on the adsorption on silica have been investigated. The results have been compared with similar studies for other nonionic surfactants.</p><p>We have found that the surfactant structure has a strong effect on the adsorption properties. An increase in the surfactant chain length increases the cooperativity of the system. An increase in the head group polymerization decreases the cooperativity and the plateau adsorbed amount at equilibrium. The effect of surfactant structure on the adsorption kinetics depends on the concentration relative to the cmc, while the there is a decrease in the rate of desorption with increasing hydrophobic chain length independent of the concentration. The adsorption/desorption process is concluded to be diffusion driven, as suggested by the model used. When comparing these results with studies on ethylene oxide based surfactants, we conclude that the two types of surfactants exhibit similar trends on surfaces onto which they adsorb.</p><p>Adsorption from binary surfactant solutions is even more interesting than adsorption from single surfactant solutions, since it brings us one step closer to the systems used in applications. In addition, adsorption from a mixture can be very different from adsorption from any of the single surfactants in the mixture. Alkyl glucosides alone do not adsorb on silica, but addition of small amounts of a cationic surfactant to the alkyl glucoside solution allows for adsorption on silica. A comparison between the adsorption and bulk properties has shown that mixed micellization explains most, but not all, effects of the coadsorption properties. Changing the pH in the mixed systems reveals that a surfactant with a pH-dependent charge and the ability to adapt its charge to the environment, e.g. a surface, enhances the adsorbed amount over a wider range of pH values than a purely cationic surfactant.</p><p>It is well known that alkyl glucosides and ethylene oxides adsorb differently on different types of hydrophilic surfaces. As a consequence, replacing ethylene oxides with alkyl glucosides might not be all straight-forward; however, we have shown that the effect of the surface can be eliminated by the use of a cosurfactant.</p>