Organically modified silicate gels

Another electro-oxidation example catalyzed by bimetallic nanoparticles was reported by D Souza and Sam-path [206]. They prepared Pd-core/Pt-shell bimetallic nanoparticles in a single step in the form of sols, gels, and monoliths, using organically modified silicates, and demonstrated electrocatalysis of ascorbic acid oxidation. Steady-state response of Pd/Pt bimetallic nanoparticles-modified glassy-carbon electrode for ascorbic acid oxidation was rather fast, of the order of a few tens of seconds, and the linearity was observed between the electric current and the concentration of ascorbic acid. 

Tsuru, K., Ohtsuki, C., Osaka, A., Iwamoto, T. and Mackenzie, J.D. (1997) Bioactivity of sol-gel derived organically modified silicates, Parti In vitro examination. Journal of Materials Science-Materials in Medicine, 8, 157-161. 

Remarkably analogous findings have been established in recent years from the study of a number of catalytic species entrapped in sol-gel glasses. In particular, molecular entrapment in hybrid organic-inorganic ceramic matrices such as organically modified silicates resulted in... 

Along with these recent technologies, sol-gel entrapped catalysts made of organically modified silicates (ORMOSIL) doped with one or... 

Figure 6.5 A fluorinated organically modified silicate doped with [Ru(dpp)3]2+ is a highly sensitive 02 sensor. Fluorine here ensures unprecedented sensitivity and a remarkable stability (2% drift over 6 months). The material has been implemented in sol-gel handheld oxygen sensors that are already commercialized. (Reproduced from ref. 6, with permission.)...

M. M. Collinson and B. Novak, Diffusion and Reactivity of Ruthenium (II) Tris(bipyridine) and Cobalt (II) Tris(bipyridine) in Organically Modified Silicates, J. Sol-Gel Sci. Technol., 2002, 23, 215. 

Bharathi S, Fishelson N, Lev O (1999) Direct synthesis and characterization of gold and other noble metal nanodispersions in sol-gel-derived organically modified silicates. Langmuir 15 1929-1937... 

In this chapter, recent progress in several key areas is reviewed. These areas are catagorized by material classification rather than by end-use application (1) bulk silica optics (2) optically active doped silica glasses (3) gel-polymer composites (4) organically modified silicates (ormosils) and (5) gradient-index glasses. These represent the five most significant developments in the area of bulk optical materials by the sol-gel process to date. 

Schmidt, H., Organically-Modified Silicates hy the Sol-Gel Process. In Better Ceramics Through Chemistry, Brinker, C. J. Clark, D. E. Ulrich, D. R., Eds. Materials Research Society Pittshurgh, PA, 1984 Vol. 32, pp 327-335. 

Research is gradually shifting to more complex systems. For instance, very few studies on lanthanide complexes doped into pure silica sol gel glasses are still appearing, whereas present work is more concentrated on lanthanide complexes in organically modified silicates and especially on complexes covalently hnked to the host matrix. But the control of the lanthanide quantity inside the host matrices remains a challenge. 

The Nile Red was doped in various sol-gels to probe their micro-polarity (Lobnik, 2001). Ormosil prepared with higher fractions oformosil precursors are stable after preparation. These materials hold great promise for gas sensing. The nanoscale properties of organically modified sol-gel-derived silicate thin films, in which Nile Red was doped at nanomolecular concentrations, were studied by single-molecule spectroscopic methods (Bardo,2001). 

Bardo A.M., Collinson M.M., Higgins D.A. Nanoscale properties and matrix-dopant interactions in dye-doped organically modified silicate thin films. Chan. Mata. 2001 13 2713-2721 Bauer R.K., de Mayo P., Ware W.R., Wu K.C. Surface photochanistry. The photophysics of pyrene adsorbed on silica gel, alumina and calcium fluoride. J. Phys. Chem. 1982 86 3781-3789 Biteau J., Chaput F., Boilot J.-P. Photochromism of spirooxazine-doped gels. J. Phys. Chem. 1996 lOfr. 9024-9031... 

Yuh S.-K., Bescher E.P., Babonneau F., Mackenzie J.D. Rare-earth doped, low hydroxyl organically modified silicates. Mater. Res. Soc. Symp. Proc. 1994 346 803-808 Zha C., Atkins G.R., Masters A.F. A spectroscopic study of an anhydrous tetraethyl orthosilicate-boric acid-ethanol system. J. Sol-Gel Sci. Tech. 1998 13 103-107 Zha C., Atkins G.R., Masters A.F. Preparation and spectroscopy of anhydrous borosilicate sols and their application to thin films. J. Non-Cryst. Sohds 1998 242 63-67. 

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