Silica functionalized

The complexes on surface of chelate-functionalized silica often include ligands available in solution in the coordination sphere. Use of a chromophore reagent as a ligand leads to the formation of colored mixed ligand complexes (MLC). The phenomena can be used as a basis for developing test-systems for visual determination of microquantities of inorganic cations in water. 

A specific example where heterogeneous supports provide nanoparticle size-control is the immobilization of homogeneous silver nanoparticles on polystyrene [366]. This work was extended later to the development of a one-pot method for the size-selective precipitation of silver nanoparticles on PVP-protected thiol-functionalized silica. During the immobilization of very small silver nanoclusters both the size of the silver nanoclusters and the thickness of the silver layer on the support could be controlled directly by the reaction parameters applied (Fi re 16) [367]. 

Preparation of Grafted Amine-Functionalized Silica. Silica was pressed, cmshed, and sieved to 40-60 mesh particles and calcined at 550°C overnight. To anhydrous toluene (40 mL), silica (1.0 g) was added under N2 and stirred for an hour. Aminopropyltriethoxysilane (APS 1.0 g, 5.58 mmol) was syringed into mixture and stirred for 24 hours at room temperature under nitrogen. The functionalized silica was then filtered, washed with toluene three times, and dried under vacuum at 50°C. 

Silica Alkylation. To tetiamethyldisihzane (TMDS, 1.0 g) in anhydrous toluene (30 mL), amine-functionalized silica was added and stirred overnight at room temperature under N2. Then it was then filtered, washed with toluene three times, and dried under vacuum at 50°C. Ethanol (190 mL) and nanopure water (10 mL) were mixed, and the pH was adjusted to 4.7 with acetic acid. Isobutyltrimethoxysilane (4.0 mL) was added to the solution, stirred for five minutes, and the modified silica was added. After 10 minutes, the solution was decanted, the... 

Reaction of Chlorodimethyl(2,3,4,5-tetramethyl-2,4-cyclopentadien-l-yl)silane with Silica Materials. Chlorodimethyl-(2,3,4,5-tetramethyl-2,4-cyclopentadien-l-yl)silane (excess) was added to a mixture of amine-functionalized silica with hexanes in a drybox. 2,6-Di-tert-butylpyridine (excess) was added as a proton sponge. The mixture was allowed to react while stirring for 24 h. The solid was filtered and washed with hexanes and THF in the drybox. The solid was then contacted with another aliquot of chlorodimethyl-(2,3,4,5-tetramethyl-2,4-cyclopentadien-l-yl)silane and the procedure was repeated. 

Metallation of cyclopentadienyl-functionalized silica materials with tetrakis (diethylamino) titanium. 

Aminosilicas have been widely studied for use in catalysis, either as a base catalyst or as a support for metal complexes (12). For example, amine functionalized silica can be used to catalyze the Knoevenagel condensation, an important C-C bond forming reaction. Also, the amine sites on the silica can be further functionalized to form supported imines, guanidine, and other species... 

A number of Rh1 diphosphine complexes were grafted on the surface of inorganic oxides such as zeolites132 or silica.133 In the latter case, catalysts prepared by reaction of [Rh(COD)2]BF4 with previously functionalized silicas give ee s up to 94.5% for this reaction. 

Fig. 8.19 SEM images of mesolamellar thin films produced by intercalation of nanosheets of (A) aminopropyl-functionalized silica or (B) AMP between stacked purple membrane fragments containing bacteriorhodopsin (scale bars= 10pm).

Amino functionalized silica nanotube for base catalyzed reaction... 

Fig. 7.11 Scavenging efficiencies of polymer-supported scavengers (a) polystyrene, (b) functionalized silica, (c) plugs, (d) lanterns] at room temperature (left) and under microwave heating (right).

Plate 16 Schematic illustration of an electrochemical immunoassay based on the poly[G]-functionalized silica NPs on carbon electrode. Diamond stands for the mouse IgG Y shape for mouse antibody red strings for poly[G] (Reproduced from [62] with permission.) (see Figure 14.7)... 

Sel et al.29 demonstrated that the pore shape and pore connectivity play the crucial role in the electrical conductivity of the functionalized silica channels. A sufficient connection between the mesopores is indispensable to allow sufficient functionalization, a facilitated electron hopping in the matrix, and a better accessibility of the electrode surface. 

Etienne, M. Cortot, J. Walcarius, A. 2007. Preconcentration electroanalysis at surfactant-templated thiol-functionalized silica thin films. Electroanalysis 19 129-138. 

Instead, the aim is to provide a unified picture of the chemistry of functional silica gels. Hence, in place of a complete coverage of what has been done with these immensely versatile materials, an attempt is made to provide readers with an understanding of the principles behind the applications. 

Without Dr Rosaria Ciriminna s exceptional chemical talent, none of what we have achieved at Palermo s CNR would have been possible. I thank her for all the creative joint work, and for a unique style, that enabled the introduction of several new sol gel functional silicas for a multiplicity of applications (and much else). 

The formation of a sol-gel functional silica gel takes place by hydrolytic polycondensation of suitable precursors in the presence of a dopant in solution. An example is given in the following (unbalanced) equation ... 

SiliCycle manufactures a number of functionalized silica gels to meet the specific requirements of pharmaceutical professionals, and has... 

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