Search results for "Silanes"
showing 10 items of 51 documents
Insights into grafting of (3-Mercaptopropyl) trimethoxy silane on halloysite nanotubes surface
2020
Abstract Functionalization of halloysite nanotubes surface by using organosilanes is sensitive to the reaction conditions. Halloysite nanotubes (HNTs) were modified using (3-Mercaptopropyl) trimethoxy silane (MPTMS). The experiments were performed under different reaction conditions including, various solvents [Toluene, Tetrahydrofuran (THF), Ethanol, n-Hexane, 1,4 Dioxane and Acetonitrile], water content in the reaction media, volume of solvent, number of moles of silane and catalysts (triethyl amine, ammonia solution and tetra-ethoxy titanium). The elemental analysis, FT-IR analysis were used to identify the samples, which attained the highest percent of functionalization. SEM image and t…
Promotion of osteogenic cell response using quasicovalent immobilized fibronectin on titanium surfaces: introduction of a novel biomimetic layer syst…
2012
Purpose Despite the undeniable potential of cell adhesion molecules such as fibronectin to support osteogenic cell responses and consecutive dental implant healing, the most beneficial mode of application onto titanium implant surfaces still requires investigation. Unspecific fibronectin adsorption on titanium dioxide (TiO2) surfaces can result in low-loading, high-desorption rates and protein–metal interactions with impaired biologic activity. The aim of the present study was to monitor the osteogenic cell responses (cell adhesion, proliferation, and differentiation) specifically to fibronectin biofunctionalized TiO2. Materials and Methods An innovative biomimetic streptavidin-biotin layer…
Improved section bonding using silanated glass slides--application protocol.
1992
Silanated slides provide excellent tissue adhesion for routine histology, immunohistochemistry and in situ hybridization of frozen, paraffin embedded material or cell smears. An easy and inexpensive method of treating glass microscope slides with triethoxysilylpropylamine is reported.
Diastereoselective synthesis of 2-phenyl-3-(trifluoromethyl)piperazines as building blocks for drug discovery.
2014
The synthesis of enantiomerically pure cis- and trans-2-phenyl-3-(trifluoromethyl)piperazines is described. It involved, as the key step, a diastereoselective nucleophilic addition of the Ruppert-Prakash reagent (TMSCF3) to alpha-amino sulfinylimines bearing Ellman's auxiliary. This methodology allows an entry into hitherto unknown trifluoromethylated and stereochemically defined piperazines, key scaffold components in medicinal chemistry.
Streoselective hemisynthesis of heterosubstituted aminoacidsApplication on radiofluorolabeling for peptide imaging.
2017
Stereoselective hemisynthesis of lateral chain heterosubstituted aminoacids.Applications on radiofluorolabeling for peptide imaging.This thesis work, which was carried out at the Institute of Molecular Chemistry of the University of Burgundy and in collaboration with the Institute of Cognitive and Integrative Neurosciences of Aquitaine, focuses on the development of new methods for the synthesis of side chain heterosubstituted amino acids including phosphine containing or silyl groups, as well as on their applications. In a first part, the synthesis of side chain silylated amino acids is achieved without racemization using a key Wittig reaction between a phosphonium salt, derived from L-asp…
Silanol suppressing potency of alkyl-imidazolium ionic liquids on C18 stationary phases
2011
Residual silanols on C18 columns yield undesirable slow-kinetics ion-exchange interactions with positively charged basic compounds that result in asymmetrical peaks, low efficiencies and long retention times. The purity of the silica employed as supporting material, and the technique used to form the bonded phase, which varies with the brand and manufacturer, give rise to different amounts of residual silanols in the packings, and consequently, different chromatographic performance. One of the most efficient and widespread strategies to reduce or even eliminate the different performance among columns is the addition of a reagent to the mobile phase to block the silanol sites. However, the i…
Practical Synthesis of Vinyl-Substitutedp-Phenylenevinylene Oligomers and Their Triethoxysilyl Derivatives
2001
Luminescent semiconducting organic compounds are widely used as active layers in electro-optical devices. Apart from conjugated polymers, monodisperse oligomers also represent attractive materials. The synthesis of stilbenoid oligomers with polymerizable end groups is presented. Oligo(phenylenevinylene)s with terminal vinyl groups 17–19 are prepared in good yields by Horner–Emmons olefinations or by the Heck reaction of the iodo-substituted oligomers 15, 16 with compressed ethene. Triethoxysilyl groups can be linked via rigid 1,2-vinylene units to the chromophores 26–30, either in the direct reaction of 14, 24 with silanes 21, 22 or by cross-metathesis of 17–19 with the vinylsilanes 21, 22 …
Intramolecular coupling of acetylenic groups of bis(alkynyl)phosphanes and silanes mediated by benzynezirconocene: a route to new mono- and tricyclic…
2004
Benzo-zirconacyclohexadiene-phospha or silacyclobutene fused ring systems are easily prepared via a benzynezirconocene intermediate by means of thermolysis of Cp 2 ZrPh 2 in the presence of bis(alkynyl)phosphanes or silanes. These polyunsaturated systems are the source of a variety of new mono- or tricyclic heterocycles incorporating either one or two heteroatoms.
Ferrocenyl-functionalized long chain branched polydienes
2009
A convenient two-step approach for the synthesis of ferrocenyl-functionalized long chain branched polydienes, based on both butadiene and isoprene, respectively, is presented. Classical living anionic polymerization was used to synthesize different AB n type poly(diene) macromonomers with moderate molecular weights between 1700 and 3200 g/mol and narrow polydispersity. Quantitative end-capping with chlorodimethylsilane resulted in the desired AB n macromonomer structures. In the ensuing Pt-catalyzed hydrosilylation polyaddition, branched, functionalized polydienes were obtained by a concurrent AB n + AR type of copolymerization with mono-and difunctional ferrocenyl silanes (fcSiMe 2 H or fc…
Molecular “Floppyness” and the Lewis Acidity of Silanes: A Density Functional Theory Study
2001
A comprehensive set of Lewis acid-base adducts of silanes was investigated by means of the density functional theory geometry optimization [B3LYP/6−31G(d)], and thermochemical calculations, [B3LYP/6−311+G(2d,p)//B3LYP/6−31G(d)]. Complex formation was found to weaken Si−Cl and Si−Br bonds more than Si−F or Si−H bonds. Comparable distances between Si and a Lewis base L (L = NH3, OH2, F−) are shorter in hexa- than in pentacoordinated complexes. The molecular structures of the pentacoordinated Si complexes allowed for a mapping of an SN2 reaction pathway by correlating the lengths of the Si−X and Si−L bonds. Complex formation was found to be exothermic for most of the coordination compounds, an…