Use of ionic liquids in sol-gel; ionogels and applications

International audienceThe current strong interest in ionic liquids is motivated by their unique combination of properties such as negligible vapour pressure, thermal stability, non-flammability, high ionic conductivity and wide electrochemical stability window. The first part of this short review deals with all the specific aspects of sol-gel in the presence of ionic liquid, which can act as drying control chemical additive, catalyst, porogenous agent and solvent or co-solvent. The second part is devoted to the properties of the gels in which the ionic liquid is kept confined (ionogels) and their applications as electrolyte membranes, optical devices, catalysts and sensors

Stability and solid-state polymerization reactivity of imidazolyl- and benzimidazolyl-substituted diacetylenes: pivotal role of lattice water

International audience1,6-Bis(1-imidazolyl)-2,4-hexadiyne (1) and1,6-bis(1-benzimidazolyl)-2,4-hexadiyne (5) have beenpreparedby a novel method that consists in refluxing excess imidazole and benzimidazole with 2,4-hexadiyne-1,6-diol bis(p-toluenesulfonate),pTS (3). This procedure is a viable alternative to the widely used Hay coupling protocol in case the target diyne possesses substituents capable of deactivating the copper catalyst by complexation. Diyne1crystallizes as a hydrate,1?H2O(2). For this compound, water is essential toachieve a crystalline material, and attempts to obtain crystals without included solvent were unsuccessful. In the structure of2, the organic fragments organize around the water molecule and interact with it through a dense network of hydrogen bonds. The CMC-CMC moieties are not oriented suitably for topochemical polymerization, and when trying to alter the organizationof the crystal by heating so as to induce polymerization, water is lost in an abrupt fashion that leads to instantaneous decomposition into polyaromatic-like species. Similar results were observed when water was removedin vacuo at room temperature. The benzimidazole-containing compound can be crystallized with water molecules (4)orwithout(5). X-ray crystallography shows that the structure of 5is organized by numerous C-H...N, C-H...p,andimidazolyl...imidazolyl p-p interactions. The diacetylene molecules almost have the right arrangement for topochemical polymerization, withpossibly reactingCMC-CMC fragments not beingparallel, a rare situation indiacetylene chemistry. Yet, experiments showthat topochemical polymerizationdoes not occur. Incorporationofwater in the lattice of5leads toa solvate that is topochemically reactive. Unlike2, however, water molecules in 4are not isolated but are organized as ribbons. Spectroscopic characterization of the polymer of4indicates that it is a blue phase polymer, with water coordinated to it. This study shows that it is possible to use water, and more generally solvent molecules, to transform a nonreactive diacetylene into a reactive one, even though this approach is less predictable than the cocrystal approach developed by Fowler, Lauher, and Goroff. The solvate approach is simple to implement, quite versatile because of the large rangeof solvents available, andonedoes not face theproblemof having to remove the host in case one needs to recover the polymer. Previous studies describing a similar approach are scarce

Coordination chemistry of thioether ligands on CuX salts: from simple 0D complexes to 3D luminescent coordination polymers

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Complexes octupolaires pour l'optique non-linéaire (de la molécule aux matériaux)

Dans cette thèse, nous avons décrit la synthèse de nouveaux complexes octupolaires à ligands bipyridines, obtenus par insertion de groupements styryle dans la chaîne conjuguée du transmetteur. Ainsi, un complexe de zinc tris(bipyridine) présentant la plus grande activité en ONL du second ordre a été décrit. Ces nouveaux chromophores ont ensuite été insérés dans des verres de fluorophosphates à bas point de fusion. La synthèse de métallo-polymères en étoile a ensuite été étudiée. Ces polymères sont formés par polymérisation du méthacrylate de méthyle par ATRP. Nous avons montré qu'il s'agit d'une méthode douce, permettant d'obtenir des polymères de structure contrôlée. Des films de très bonnes qualités optiques, qui conservent les propriétés optiques des polymères, ont été élaborés. Enfin, nous avons appliqué l'ATRP à l'élaboration de matériaux polymères photoisomérisables. Pour la première fois, des non-linéarités macroscopiques ont été obtenues par orientation tout optique.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Loading-Controlled Stiffening in Nanoconfined Ionic Liquids

International audienceAn important strategy for using ionic liquids is to immobilize them by impregnation cif supports or incorporation into porous solids to obtain materials called "ionogels". Of considerable importance for applications (electrolyte membranes, supported catalysts, etc.), such confinement results in dramatic changes in the physicochemical properties of the ionic liquid. Here, we report molecular simulations of a silica nanopore that is gradually filled with a typical imidazolium salt ionic liquid to obtain a realistic model of these ionogels. Despite the significant layering and stiffening of the ionic liquid in the vicinity of the silica surface, the pair correlation functions and magnitude of its dynamics clearly evidence liquid-like behavior. An increase in the self-diffusivity and ionic conductivity, associated with a decrease in the characteristic residence times of ions at the silica surface, is observed upon increasing the loading as the ionic liquid fills the nanopore center and tends to recover its bulk properties

Ruthenium cluster chemistry: monodentate bis(diphenylphosphino)acetylene-ligated cluster modules in chain and dendrimer formation

Reaction of Ru3(μ-dppm)(CO)10 [dppm = bis(diphenylphosphino)methane] with one equivalent of dppa [dppa = bis(diphenylphosphino)acetylene] afforded Ru3(μ-dppm)(CO)9(η1-dppa) which possesses a monodentate dppa ligand,an X-ray structural study revealing

Ruthenium cluster chemistry monodentate bis(diphenylphosphino)acetylene-ligated cluster modules in chain and dendrimer formation

International audienceReaction of Ru3(l-dppm)(CO)10 [dppm = bis(diphenylphosphino)methane] with one equivalent of dppa [dppa = bis(diph- enylphosphino)acetylene] afforded Ru3(l-dppm)(CO)9(g1 -dppa) which possesses a monodentate dppa ligand, an X-ray structural study revealing that all phosphorus donor atoms are arranged in equatorial coordination sites with respect to the triruthenium cluster plane. Reaction of Ru3(CO)9(NCMe)3 with excess dppa afforded fair yields of Ru3(CO)9(g1 -dppa)3,which possesses three monodentate dppa ligands. Reaction of three equivalents of Ru3(l-dppm)(CO)9(g1 -dppa) with Ru3(CO)9(NCMe)3 or reaction of Ru3(CO)9(g1 -dppa)3 with excess Ru3(l-dppm)(CO)10 afforded low yields of the dodecanuclear first-generation dendrimer Ru3(CO)9{PPh2C2PPh2Ru3- (l-dppm)(CO)9}3. Reaction of WIr3(l-CO)3(CO)8(g-C5Me5) with excess Ru3(l-dppm)(CO)9(g1 -dppa) afforded fair yields of the deca- nuclear dppa-bridged tri-cluster WIr3(CO)9{PPh2C2PPh2Ru3(l-dppm)(CO)9}2(g-C5Me5)

Selective Cobalt over Nickel separation using neat and confined ionic liquids

International audienceTask Specific Ionic Liquids (TSILs) generated by association between tetraalkylammonium cations and coordinating anions such as dicyanamide (Dca-) and thiocyanate (SCN-) were used for the selective separation of Ni(II) over Co(II). SCN-based TSIL presents higher extraction efficiency than the Dca-based one towards Co(II) (E = 85.4 % vs 54.6 %) and Ni (II) (E = 22 % vs 0.5%) but lower separation factors (βCo/Ni = 21 vs 239). Interestingly, extraction of Co(II) and Ni(II) in Dca-based TSIL can be enhanced using salts with chaotropic anions such as NaNO3 (E > 90 % for Co(II) and E = 85% for Ni(II)). The use of NaCl allows, moreover, the efficient separation of both ions with βCo/Ni >1000. The metal can be recovered from the IL phase using Na2SO4 aqueous solution to limit the release of the IL and to ensure a good recyclability of this latter. The confinement of TSIL in silica –matrix ionogel constitutes a valuable method to improve the handling of the IL. Indeed, the extraction properties of the ionogel containing [THN][Dca] IL are very close to those obtained using the same neat IL with an efficient separation of Co(II) over Ni(II) in NaCl 4 mol.L-1 (βCo/Ni >1000). Finally, the recyclability of the ionogel was studied and found comparable to that of neat IL

Silica ionogels and ionosilicas

International audienceThis chapter provides an overview of the recent developments in the preparation of silica ionogels and ionosilicas and of the applications of these materials derived from ionic liquids (ILs) or inspired by them in some topical fields as electrochemical and optical devices, environmental sustainability, and pharmaceuticals. Besides applications in catalysis, ionosilicas offer great opportunities in the fields of separation and molecular recognition. The chapter emphasizes that ionosilicas should be considered as a distinct family in the area of silica hybrid materials. Surface-functionalized ionosilicas are generally synthesized either via postsynthesis grafting or hydrolysis–cocondensation reactions involving trialkoxysilylated ionic precursors. The chapter illustrates the two different synthetic methods involving a monosilylated imidazolium precursor 3-methyl-1-(3-(triethoxysilyl) propyl)-imidazolium chloride. Cocondensation reactions involving ionic compounds are of particular interest in soft templating approaches to nanostructured ionosilicas as the ionic nature of the precursor offers the possibility to induce modified precursor–surfactant interactions

"TTF[Ni(dmit)2]2 :Now as Nanoparticles"

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