Search results for "Silanes"
showing 10 items of 51 documents
Complement proteins regulating macrophage polarisation on biomaterials
2019
[EN] One of the events occurring when a biomaterial is implanted in an host is the protein deposition onto its surface, which might regulate cell responses. When a biomaterial displays a compromised biocompatibility, distinct complement pathways can be activated to produce a foreign body reaction. In this article, we have designed different types of biomaterial surfaces to study the inflammation process. Here, we used different concentrations of (3-glycidoxypropyl)-trimethoxysilane (GPTMS), an organically-modified alkoxysilane as a precursor for the synthesis of various types of sol-gel materials functionalizing coatings for titanium implants to regulate biological responses. Our results sh…
Role of the functional group in n-octydimethylsilanes in the synthesis of C8 reversed-phase silica packings for high-performance liquid chromatography
1986
Abstract C8 reversed-phase packings have been sysnthesised by reaction of a 25-nm pore-size high-performance liquid chromatographic silica (10 μm, as(BET) = 297 m2 g-1) with 2,4-lutidine as base and dichloromethane and N,N-dimethylflormamide as solvents, or without solvents and with the following silanes: n-octyldimenthylchlorosilane (C8-Cl), n-octyldimethylhydroxysilane (C8-OH), n-octyldimethylmethoxysilane (C8-OCH3), n-octyldimethylethoxysilane (C8-OC2H5), n-octyldimethyl(dimethylamino) silane [C8-N(CH3)2], n-octyldimethyl(trifluoroacetoxy)silane (C8- OCOCF3), and bis-(n-octyldimethylsiloxane) (C8-O-C8). C8-Cl, C8-OH and C8-OCH3 each form a reactive intermediate with 2,4-lutidine, favouri…
Cyclic metal(oid) clusters control platinum-catalysed hydrosilylation reactions : from soluble to zeolite and MOF catalysts
2020
The Pt-catalysed addition of silanes to functional groups such as alkenes, alkynes, carbonyls and alcohols, i.e. the hydrosilylation reaction, is a fundamental transformation in industrial and academic chemistry, often claimed as the most important application of Pt catalysts in solution. However, the exact nature of the Pt active species and its mechanism of action is not well understood yet, particularly regarding regioselectivity. Here, experimental and computational studies together with an ad hoc graphical method show that the hydroaddition of alkynes proceeds through Pt-Si-H clusters of 3-5 atoms (metal(oid) association) in parts per million amounts (ppm), which decrease the energy of…
Aryldimethylsilyl Modified Hypersilanes
2008
Aryldimethylsilyl-substituted hypersilanes ArSiMe2Hyp [Hyp =Si(SiMe3)3; Ar = Mes (3a), Bph (3b), Mph (3c), Pph (3d), Tph (3e); Dpp (3f); with Mes = 2,4,6-Me3C6H2, Bph = 2-PhC6H4, Mph = 2-MesC6H4, Pph = 2′,3′,4′,5′,6′-pentamethylbiphenyl2-yl, Tph = 2′,4′,6′-triisopropylbiphenyl-2-yl and Dpp = 2,6-Ph2C6H3] have been synthesized by a multi-step reaction starting from the readily available starting materials ArI and (thf)xKHyp. For this purpose the aryl iodides were first converted into the lithium aryls by lithium-halogen exchange with n-butyl lithium. A salt-metathesis reaction with SiMe2Cl2 gave the corresponding arylchlorodimethylsilanes (2a–e) in excellent yields. Finally, reaction of 2a–e…
Fluoreszierende silane als OH-selektive schutzgruppen
1985
Abstract Fluorescent tertiary silanes are synthesized which, under cesium fluoride/ imidazole activation, discriminate between primary and secondary OH groups. Serine n-butylamide reacts with [5-dimethylamino(1-naphthyl)]dimethylsilane ( 1 ) and diisopropyl[5-dimethylamino(1-naphthyl)]silane ( 2 ) to form the silyl ethers (−)- l -3-[5-dimethylamino(1-naphthyl)]-dimethylsilyloxy]serine n-butylamid ( 14 ) and (−)- l -3-[diisopropyl[5-dimethylamino(1-naphthyl)]silyloxy]serine n-butylamid ( 15 ) exclusively. The silyl ethers are cleaved on treatment with H 2 F 2 , forming the corresponding fluorescent silyl fluorides. Absorption and fluorescence data as well as stability data for the hydrolysis…
Alkoxysilyl substituted oligo(phenylenevinylene)s: chromophores with reactive side chains
2003
The synthesis and properties of highly luminescent oligo(phenylenevinylene)s (OPV) with curable alkoxysilyl groups are described. Two diethoxymethylsilane moieties are connected directly or through flexible spacers to monodisperse alkoxy-substituted OPVs via hydrosilylation of alkinyl and allyloxy groups, Heck reaction with silylstyrene or condensation of aldehydes with aminopropyl silanes. Hydrolysis of the alkoxysilanes yields silanols condensing to curable three-dimensional networks, thus allowing the transformation of small molecules to transparent and fluorescent films with well-defined chromophores.
Palladium on Charcoal as a Catalyst for Stoichiometric Chemo- and Stereoselective Hydrosilylations and Hydrogenations with Triethylsilane
2014
Stoichiometric quantities of triethylsilane in the presence of activated Pd/C as the catalyst can be used to effect chemo-, regio-, and stereoselective hydrosilylation and transfer hydrogenation reactions. α,β-Unsaturated aldehydes and ketones are selectively hydrosilylated to give the corresponding enol silanes or transfer hydrogenated to give the saturated carbonyl compounds in the presence of other reducible functional groups.
Alkoxysilylation of π-systems with extended conjugation—reactive chromophores for organic–inorganic hybrid materials
2004
Luminescent stilbenoid chromophores with diethoxysilane end groups are prepared via Heck reactions. Diethoxysilane-substituted styrenes are used as vinylic components, thus allowing the combined connection of the chromophore to the silane moiety with an extension of the π-system. 1,4-Distyrylbenzenes with a terminal bromine are used as coupling partners. The electrical and optical properties the four-ring OPVs are tuned via substitution with donating alkoxy side chains and electron withdrawing cyanide and a naphthyl-1,2,3-oxadiazole moiety. Hydrolysis yields film forming and luminescent cyclosiloxanes.
Tris- and tetrakis-[oligo(phenylenevinylene)]silanes: synthesis and luminescence behaviour
2002
Abstract The connection of three or four monodisperse oligo(phenylenevinylene)s to a central silicon atom is performed via Wittig–Horner reactions. The terminal rings are substituted with alkoxy side chains. Depending on the ratio of the lengths of the rigid conjugated units and the flexible side chains, transparent films can be obtained from several of these trigonal-pyramidal or tetrahedral molecules. An intense fluorescence in the blue-green region is emitted by molecules of either shape. These compounds are interesting as active materials for electro-optical applications due to their intense fluorescence and improved film forming capability.
The synthesis and condensation of oligo(phenylenevinylene)s with alkoxysilyl end groups
2002
Monodisperse alkoxylated oligo(phenylenevinylene)s with 3, 4, or 5 benzene rings were connected to reactive di- and triethoxysilanes, either directly or via flexible spacers. Aminopropylsilanes were condensed with stilbenoid aldehydes and subsequently reduced to amines, for the direct, rigid connection, the Heck reaction and also cross-metathesis with vinyl silanes proved to be successful routes. Hydrolysis of the ethoxysilanes leads to polymerisable cyclosiloxanes or curable three-dimensional networks with pendent chromophores.