Luminescent silica precursors

This approach is effective, but a significant amount of synthetic expertise and effort is required. For each luminescent probe to be incorporated into an aerogel, one must first tether the probe to a silica precursor chemical, and do so in a way that does not compromise the emission characteristics of the probe. 

Green W.H., Le K.P., Grey J., Au T.T., Sailor M.J. White phosphors from a silicate-carboxylate sol-gel precursor that lack metal activator ions. Science 1997 276 1826-1828 Harreld J.H., Ebina T., Tsubo N., Stucky G. Manipulation of pore size disUibutions in silica and ormosil gels dried under ambient pressure conditions. J. Non-Cryst. Sohds 2002 298 241-251 Hazenkamp M.F., Blasse G. Rare-earth ions adsorbed onto porous ass luminescence as a characterizing tool. Chem. Mater. 1990 2 105-110... 

The rare earth tetrakis P-diketonate complex functionalized silica spheres are conveniently prepared by a one-pot synthesis method which is based on the modified Stober process [56]. The resulted luminescent nanoparticles are shown schematically in Fig. 8.9 (top). Because the introduction of siloxy-bearing rare earth complex precursor can result in coagulation, a step-by-step approach is adopted to implement the synthesis of uniform silica sphere. The rare earth complex precursors added into the reaction system in the second step can ensure the size uniformity of the nanoparticles furthest. As a result, the rare earth chelate mainly lies in the outer layer of the silica sphere, which has been shown schematically in Fig. 8.9 [55]. As shown in Fig. 8.9 (bottom), the nanoparticles obtained are uniform spheres, approximately 61 5 nm in diameter. And there is no obviously change in the particle size or morphology. All nanoparticles show relatively high luminescent lifetimes. Among the quantum efficiencies, the experiment values of Eu-TTA-SS (34.8 %)... 

---