Nanoporous silica

Gies FI, Marler B and Werthmann U 1998 Synthesis of porosils crystalline nanoporous silicas with cage- and channel-like void structures Moiecuiar Sieves Science and Technoiogy vo 1, ed FI G Karge and J Weitkamp (Berlin Springer) pp 35-64... 

U. (1998) Synthesis of porosils Crystalline nanoporous silicas with cage-and channel-like void structures in Molecular Sieves Science and Technology, vol. 1 (eds H.G.Karge and ). Weitkamp), Springer, Heidelberg, pp. 35-64. 

Raman, N.K., Anderson, M.T. and Brinker, C.J. (1996) Template-based approaches to the preparation of amorphous, nanoporous silicas. Chemistry of Materials, 8, 1682-1701. 

Wei, Y., Xu, J., Feng, Q., Lin, M., Dong, H., Zhang, W.-J. and Wang, C. (2001) A novel method for enzyme immobilization direct encapsulation of add phosphatase in nanoporous silica host materials. Journal of Nanoscience and Nanotechnology, 1, 83-93. 

Kramer, E. Forster, S. Goltner, C. Antonietti, M. 1998. Synthesis of nanoporous silica with new pore morphologies by templating the assemblies of ionic block copolymers. Langmuir 14 2027-2031. 

Goltner, C. G. Berton, B. Kramer, E. Antonietti, M. 1999. Nanoporous silicas by casting the aggregates of amphiphilic block copolymers The transition from cylinders to lamellae and vesicles. Adv. Mater. 11 395-398. 

Refractometry Using Nanoporous-Silica-Supported and Freestanding Waveguides... 

Hence, the mode only experiences the nanoporous silica, the film, and the cover medium resulting in a pure monomode operation. 

Fig. 15.7 Incoupling resonant peaks of nanoporous silica supported polystyrene waveguide. Reprinted from Ref. 13 with permission. 2008 American Institute of Physics...

Bacterial Cell Detection Using Nanoporous-Silica-Supported... 

The grating-coupled nanoporous-silica-supported reverse waveguide chip was also applied for monitoring the attachment and spreading of Human Dermal Fibroblast cells to the surface16. As in the bacteria experiments, the waveguide surface was coated with a thin layer of poly-L-lysine layer to improve cell attachment and spreading. 

The nanoreplication of functional nanostructures has also been achieved through other block copolymer-templated structures. De Boer et al. [35] applied honeycomb-structured films of rod-coil block copolymer as patterned templates to replicate hexagonally packed arrays of aluminum cups on the substrate surfaces (Fig. 10b). Nguyen et al. [237] embedded semiconducting polymers in the channels of oriented hexagonal nanoporous silica and used this nanoscale architecture to control the energy transfer for potential optoelectronic applications. 

If we extend this vision to the biocatalysis at silicon, as reported in some of the recent papers,641 642 and continue learning from nature how to be bioinspired in making nanoporous silicas and other membranes, then, what seemed to be true in Goody s remark about liquid crystals, might also apply to the whole field of silicones new field lies open for the development of materials for which their design is only limited by human imagination. 256... 

For some reviews, see (a) Majoral J-P (2007) Influence of cationic phosphorus dendrimers on the surfactant-induced synthesis of mesostructured nanoporous silica. New J Chem 31 1259-1263 (b) Puntoriero F, Nastasi F, Cavazzini M et al (2007) Coupling synthetic antenna and electron donor species a tetranuclear mixed-metal Os(II)-Ru(II) dendrimer containing six phenothiazine donor subunits at the periphery. Coord Chem Rev... 

Assembly of nanoporous silica ia amphoteric surfactant templating scheme... 

The incorporation of a cationic azobenzene derivative, p-( a> -dimethyl-ethanolammonioethoxyj-azobenzene bromide, into nanoporous silica films and the photochemical reactions of the adsorbed dye were investigated. The nanoporous silica films were prepared from tetramethoxysilane and octadecyltrimethyl-ammonium chloride by the rapid solvent evaporation method which we have reported previously. The adsorption of the cationic azo dye was conducted by casting an ethanol solution of the dye onto the nanoporous silica films. Upon UV light irradiation, trans-azobenzene isomerized photochemically to the c/s-form and photochemically formed c/ s-form turned back to the frans-form upon visible light irradiation. The nanoporous silica films were proved to be an excellent reaction media to immobilize organic photocromic species. 

The immobilization of photoactive species into the silica-surfactant mesostructured materials is worth investigating toward future photofunctional materials. Photochemistry on solid surfaces is a growing new field which yields a wide variety of useful application such as sensitive optical media, reaction paths for controlled photochemical reactions, molecular devices for optics, etc. [17] Along this line, the incorporation of organic dyes into silica-surfactant mesostructured materials [17-20] as well as nanoporous silica films[3] have been reported so far. 

We now report the photochromic reaction of an azobenzene in the nanoporous silica film. Since the photochromic behavior is environmentally sensitive, photochromism of organic substances in solid matrices has been investigated to understand as well as to modify the photochromic behavior.[21] Photochromism of azobenzene and its derivatives due to cis-trans isomerization (Scheme I) has widely been investigated. Photocontrol of chemical and physical functions of various supramolecular systems has vigorously been studied by using photochemical configurational change of azobenzene derivatives.[22,23]... 

The thin film of silica-surfactant mesostructured material was prepared by the reactions of TMOS and C18TAC, as reported previously[3]. The film was calcined in air to prepare nanoporous silica films. The adsorption of the dye onto the nanoporous silica film was conducted either by immersing the calcined film into an ethanol solution of the dye or casting the solution onto the film. 

Figure 1b), showing that the ordered microstructure was retained even after the removal of surfactants. The d value of the calcined film was 4.1 nm. The SEM image of the film surface (data not shown) also indicates that the film is continuous and crack free. These observations are well consistent with those reported in the previous paper[2], showing the formation of silica-surfactant mesostructured material and the successful transformation of the as coated film into a nanoporous silica film. 

The loading amounts of the dyes, the pore size and surface modification are expected to affect the photoprocesses of the adsorbed dyes. In order to construct molecularly designed functional host-guest systems from nanoporous silica films, further study on the adsorption and the photoprocesses of the dyes is now underway and will be reported subsequently. 

The design of the nanoporous waveguide is shown both schematically and as a photograph in Fig. 12. It consists of an 8 mm x 12 mm x 1.6 mm soda lime glass substrate, spin-coated with a l- im-thick layer of nanoporous silica (Nanopore, NM, USA) and then coated with a 160-nm-thick layer of polystyr-... 

Figure 18.4 Fabrication and operation of a hybrid organic—inorganic nanovalve based on grafting of valve functionality to preformed nanoporous silica, (a) Grafting of ICTES to the surface of the mesoporous silica powders (b) linkage of a dialkylammonium pseudorotaxane to the surface of the silica through reaction with ICTES (c) loading of the pore volume with molecules (d) closing of the nanovalve by complexation of the dialkylammonium pseudorotaxane with a crown ether and (e) release of the pore volume contents by disruption of the crown ether-ammonium complex.

Azobenzene has also been added to the internal surface of mesoporous films and powders through postsynthesis grafting.58,60-62 The effect of oligomer size on azobenzene isomerization kinetics was studied for branched oligomer-modified azobenzene derivatives in solution and covalently grafted to nanoporous silica 61 the size of the dendrimer had little effect on the thermal cis to trans isomerization rate in solution... 

J. Brown, L. Mercier, and T. J. Pinnavaia, Selective adsorption of Hg2+ by thiol-functionalized nanoporous silica, Chem. Commun. 69-70 (1999). 

Ahn BJ, Gang MS, Chae K et al (2008) A microwave-assisted synthesis of 3, 4-dihydro-pyrimidm-2-(lH)-ones catalyzed by FeCl3-supported nanopore silica under solvent-free conditions. J Ind Eng Chem 14 401 05... 

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