Azaphosphatrane Organocatalysts in Confined Space: Cage Effect in CO2 Conversion

International audienceThe endohedral functionalization of a molecular cage by an azaphosphatrane unit has allowed for the creation of highly engineered catalytic cavities for efficient conversion of CO2 into cyclic carbonates. Strong structure/activity/stability correlations have been demonstrated by careful adjustment of the size, shape, and electronic properties of the hemicryptophane host

Azaphosphatrane Cations: Weak Acids, Robust Phase-transfer Catalysts

International audienceThe use of azaphosphatrane derivatives, which are the acidic counterparts of the well-known proazaphosphatrane superbases (also named Verkade’s superbases), are found to function as phase-transfer catalysts. In four representative protocols of phase-transfer catalytic reactions—two alkylations of enolates, one generation of carbene, and one oxidation of an electrophilic alkene—azaphosphatranes act as catalysts in biphasic heterogeneous media

N-Heterocyclic Carbene Formation Induced Fluorescent and Colorimetric Sensing of Fluoride Using Perimidinium Derivatives

International audienceIn this study, two perimidinium derivatives (1 and 2) were designed, synthesized, and developed as efficient fluorescent and colorimetric chemodosisensors for F− in DMSO or more competitive media (DMSO containing 10 % water). In the presence of F−, the yellow and non-fluorescent solution of 1/2 became colourless and exhibited strong blue fluorescence. This unique spectroscopic behaviour of 1/2 towards F− was attributed to the formation of N-heterocyclic carbene deprotonated by F−, which immediately reacted with water to give a colourless and fluorescent carbinol. Interestingly, it was found that this carbinol intermediate was unstable and further underwent a redox disproportionation to generate two other optically changed compounds. All the proposed mechanisms for the sensing process have been carefully confirmed by experiments

Encapsulation of Azaphosphatranes and Proazaphosphatranes in Confined Spaces

International audienceProazaphosphatranes (also named Verkade's superbases) and their azaphosphatrane conjugated acids have been recently been shown to be confined in either covalent or self-assembled molecular cages, or immobilized in nanopores of hybrid materials. The encapsulation of these phosphorus moieties turns out to strongly affect both their acid-base, catalytic, and recognition properties. The thermodynamics and kinetics of the proton transfer as well as the selectivity and catalytic activities of Verkade's superbases were strongly changed upon their confinement in a hemicryptophane cavity. Moreover, selfassembled cages, including azaphosphatrane moieties, were found to display remarkable anion recognition properties in water. In this Minireview, these new aspects of the chemistry of aza-and proaza-phosphatranes are presented, in order to highlight the great potential of such an approac

Introduction à la chimie supramoléculaire - Concepts – Chimie hôte-invité

International audienceDepuis la fin des années soixante, la chimie supramoléculaire est devenue unebranche multidisciplinaire de la chimie couvrant de vastes domaines d'investigation avecdes connexions fortes avec la biologie ou la science des matériaux. Cet article présenteles interactions intermoléculaires non covalentes et leur mise en œuvre dans lephénomène de reconnaissance moléculaire. Loin d'être exhaustif, il cherche d'abord àillustrer au travers d'exemples représentatifs les principes et méthodes conduisant à descomplexes de type « hôte-invité », mettant en exergue le développement des récepteursmoléculaires synthétiques et leurs applications

SYNTHESE ET PROPRIETES COMPLEXANTES DE PHOSPHACAVITANDS FONCTIONNALISES

LYON-ENS Sciences (693872304) / SudocSudocFranceF

Hemicryptophane–oxidovanadium(V) complexes: Lead of a new class of efficient supramolecular catalysts

International audienceHemicryptophane–oxidovanadium(V) complexes 1 and 2 were tested in the oxidation of sulfide to sulfoxide. They were found to be efficient supramolecular catalysts in the oxidation of thioanisol with yields up to 95%. Furthermore, turnover up to 180 was obtained by decreasing the amount of catalyst to 0.5% molar. A direct comparison between hemicryptophane complexes 1 and 2 and the model complex 3, which lacks a cavity, was made. The cage structure in 1 and 2 strongly enhanced the catalytic activity, and higher yields were obtained with 1 or 2 than with the model compound 3. Kinetic constants for the oxidation of thioanisol were estimated up to sixfold higher with the hemicryptophane complexes than with the model complex 3

Synthèse, complexation et auto-association de cavitands phosphorés fonctionnalisés

LYON-ENS Sciences (693872304) / SudocSudocFranceF

Les accidents par la aesoxsrcorticosthrone Gans le traiter:-ent de la r. aladie d'Ad dis on.

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Les phosphonatocavitands pour la conception de récepteurs chiraux et de capsules supramoléculaires

Les phosphonatocavitands sont des molécules présentant une cavité moléculaire aromatique lipophile, avec un ensemble de sites de complexation durs à la périphérie de la cavité, constitué de groupements phosphonate. Il en résulte une très forte affinité pour des cations métalliques et ammoniums, ainsi que les alcools qui forment des liaisons-H fortes avec les groupements phosphorylés. jusqu'alors synthétisés majoritairement sous forme tétrafonctionnalisée par des groupements phosphoryles de stéréochimie i , nous avons mis en place une voie de synthèse permettant d'obtenir sélectivement les composés di et tri phosphorylés tout en conservant la stéréochimie i des ponts. Nous avons alors mis en évidence la formation en solution de capsules moléculaires non covalentes sans ajout de substrat. L'étude des propriétés de complexation de ces capsules a conduit à la réalisation d'un système gyroscopique. Ces cavitands partiellement phosphorylés ont ensuite été utilisés afin d'y ajouter de nouvelles fonctionnalités. L'ajout d'un groupement N-méthyltolylpyridinium à un triphosphonatocavitand a permis d'obtenir, par auto-association, un dimère. Nous avons observé que dans certaines conditions de solvant, ces dimères pouvaient évoluer en oligomères de tailles supérieures? L'ajout à un diphosphonatocavitand d'un groupement quinoxaline ou d'un groupement phosphorylé différent, a conduit à l'obtention, sous forme racémique, de cavitands chiraux par dissymétrisation de la cavité aromatique. Les premiers résultats obtenus lors de la complexation d'ammonium chiraux ont montré une énantiosélectivité, ces cavitands pourraient être utilisés pour la reconnaissance sélcetive d'énantiomères d'ammoniums et d'alcools. Enfin, des cavitands phosphorés mixtes, possédant à la fois des fonctions phosphoryles et thiophosphoryles, ont été synthétisés. Leurs propriétés de complexation restent à étudier.The phosphonatocavitands are molecules which possess a lipophilic molecular cavity combined with several "hard" phosphorylated (P=O) binding sites that can be oriented towards the inside of the cavity. These particular cavitands show good binding properties towards alcohols, metal ions and more interestingly towards ammonium. They were hitherto synthetised in tretrafunctionnalized form by phosphorylated groups in stereochemistry i ; i made a synthesis path which allowed to obtain selectively di and trifunctionnalized compounds while maintaining the stereochemistry i of the bridges. I then demonstrated the formation of non covalent supramolecular capsules in solution, whithout any addition of substrates. The study of the capsules binding properties led to the building of a gyroscopic system. Subsequently these partially phosphorylated cavitands have been used so that new functionalities were added to them. I grafted a N-methylpicolium group to a triphosphonatocavitand to obtain, by self-assembling, a dimeric species. I noticed that the dinner could evolve in oligomeric species with a higher molecular weight in certain solvent conditions. The addition of a quinoxaline group or a different phosphoralyted group to a diphosphonatocavitand led to obtain chiral cavitands in racemic form by desymmetrization of the aromatic cavity. The first results obtained during chiral ammonium complexation experiment show an enantioselectivity, these cavitands could be used for selective recognition of ammonium or alcohol enantiomers. Eventually, mixed phosphoralyted cavitands, which possess both phosphoryl and thiophosphoryl groups, were prepared. Their binding properties have not been studied yet.LYON-ENS Sciences (693872304) / SudocSudocFranceF