Doped sol-gel materials

D. Avnir, Organic Chemistry within Ceramic Matrixes Doped Sol Gel Materials, Acc. Chem. Res., 1995, 28, 328. 

Other properties which have contributed to the attractiveness and versatility of the sol-gel doping approach are the chemical, photochemical and electrochemical inertness as well as the thermal stability of the matrix the ability to induce electrical conductivity16 the richness of ways to modify chemically the matrix and its surface as well as the above-mentioned controllability of matrix structural properties the enhanced stability of the entrapped molecule1,17 the ability of employing the chromatographic properties of the matrix for enhanced selectivity and sensitivity of reactions with the dopant4 the simplicity of the entrapment procedure the ability to obtain the doped sol-gel material in any desired shape (powders, monoliths, films, fibers) and the ability to miniaturize it18,19. 

Fig. 15.7 Library of erythrosine B doped sol-gel materials for oxygen sensing. Diversity is addressed by binary mixtures of three alkoxysilanes tetramethoxysilane, methyl-trimethoxysilane, and dimethyl-dimethoxysilane...

Avnir D. Organic chemistry within ceramic matrices doped sol-gel materials. Acc Chem Res. 1995 28 328-34. 

The use by Avnir and co-workers (21) of excited-state dynamics of pyrene-doped sol-gel materials to probe the interior of the sol-gel environment has helped pave the way for similar smdies with luminescent probes such as [Ru(bpy)3] (14). From an applications standpoint, the attributes of [Ru(bpy)3] (Section lll.D.2.b) make this metal complex a particularly good O2 sensor. The matrix can have an enormous effect on O2 diffusibility to the doped sensor depending on the conditions of synthesis. The sensing ability of [Ru(bpy)3] " is probably best suited for gas-phase O2 as the molecule has been shown to leach from sol-gels under solution conditions (146). A typical optically based O2 sensing device using such a system is shown in Fig. 23 (143). 

From the point of view of optics applications, luminescent dyes (fluorescent and phosphorescent) were the organic compounds most frequently used for the preparation of doped sol-gel materials. The characteristics of these materials were studied extensively, from properties at the steady state (emission-excitation) to properties of the dynamic state (lifetimes), and to properties derived from anisotropy and/or energy transfer. Knowledge of the effects that the surface may have on the organic molecule is an important factor in understanding the spectroscopic properties of the entrapped molecule in its inorganic/organic environment. 

This paper has reviewed the dye-doped sol-gel materials, particularly focusing on the molecular probes of sol-gel materials and molecular interactions with sol-gel matrices. The... 

Dai S., Sigman M.E., Burch E.L. Preparation of a photochromic glass doped with methylviologen radical cation via a sol-gel process. Chem. Mater. 1995 7 2054-2057 del Monte F., Levy D. Formation of fluorescent rhodamine B J-dimers in sol-gel glasses induced by the adsorption geometry on the silica surface. J. Phys. Chem. B 1998 102 8036-8041 Dunn B., Mackenzie J.D., Zink J.I., Stafsudd O.M. Solid-state tunable lasers based on dye-doped sol-gel materials. Proc. SPIE vol. 1328 Sol-Gel Optics 1990 1328 174-182 Dunn B., Zink J.I. Probes of pore environment and molecule-matrix interactions in sol-gel materials. Chem. Mater. 1997 9 2280-2291... 

L6pez T., G6mez R. Catalyst doped sol-gel materials. In Sol-Gel Optics Processing and Applications, Klein L.C., ed. Norwell, USA. Kluwer Academic Publishers, 1994, pp. 345-371 Lubda D., Cabrera K., Nakanishi K., Minakuchi H. Sol-Gel products news. Monolithic HPLC silica columns. J. Sol-Gel Sci. Technol. 2002 23 185-187 MacChesney J.B., Johnson D.W., Bhandarkar S., Bohrer M.P., Fleming J.W., Monberg., Trevor D.J. Optical fibers by a hybrid process using sol-gel silica over cladding tubes. J.Non-Cryst. Sol. 1998 226 232-238... 

Canva M., Geordes P., Perelgritz J.F., Brum A., Chaput F., Boilot J.P. Perelene and pyrromethen doped xerogel for a pulsed laser. Appl. Opt. 1995 34(3) 428-431 Canva M., Roger G., Cassagne F., Levey Y., Brun A., Chaput F., Boilot J.P., Rapaport A., Heerdt C., Bass M. Dye-doped sol-gel materials for two-photon absorption induced fluorescence. Opt. 

Likewise, we will exclude from the review most studies on organic and metallic compounds absorbed on surfaces of supports (even if the supports were processed by the sol-gel technology or organically modified) despite the fact that some supported catalysts are as active as the respective doped sol-gel materials (Price, 2000 Lu, 2002 Clark, 2000). 

Rosenfeld A., Avnir D., Blum J. Sol- el encapsulated transition metal quaternary ammonium ion pairs as highly efficient recyclable catalysts. J. Chem. Soc., Chem. Commun. 1993 583 584 Rosenfeld A., Blum J., Avnir D. Disproportionation of dihydroarenes by soL el entrapped RhCls-quaternary ammonium ion pair catalysts. J. Catal 1996 164 363-368 Sarussi L., Blum J., Avnir D. Doped sol gel materials as heterogeneous reagents for organic synthesis. J. Sol-Gel Sci. Tech. 2000 19 17-22... 

Kumar, D.N., and Prasad, P.N. (1997) Novel organic-doped sol-gel materials for photonics multiphasic nanostructured composites monolith and optical fibers. Appl Organomet. Chem., 11,107-127. 

Samuel, J. Strinkovski, A. Shalom, S. Lieberman, K. Ottolengbi, M. Avnir, D. Lewis, A. Miniaturization of organically doped sol-gel materials a microns-size fluorescent pH sensor. Mater. Lett. 1994,21,431 34. 

Fig. 4 Femtosecond laser written structures with a complicated material recipe, a A 3D spiral structure within silver-doped sol-gel materials. The latent image was produced using multiple exposures with an 800-nm, 120 fs laser, b Image of the actual 3D silver structure fabricated in a nanoparticle-seeded polymer nanocomposite by two-photon laser exposure the upper image was reconstructed from a series of two-photon fluorescence microscopy images obtained at various depths in the sample and the lower SEM image of the free-standing 3D silver structure is the same as the upper one after removal of unexposed material using dichloromethane...

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