Sol-gel xerogel

Materials Research Society Sol gels, xerogels and Aerogel ceramics... 

The fluorescence spectrum of pyrene has been very often nsed as a photophysical probe. The fluorescence spectmm shows the vibronic strnctnre, which is sensitive to the polarity of the environment (Nakajima, 1971 Kalyanasnndaram, 1977). Moreover, pyrene forms excimer due to one molecnle in the groimd state and one in the excited state for concentrated systems. Therefore, fluorescence spectra of pyrene can be expected to reveal the stmctnral changes of sol-gel silica and trapping mechanism of organic molecnles along the sol-gel-xerogel transitions... 

The fluorescence level inversion of 1-naphthol from La to Lb occurred after the gelation ofTEOS, while the fluorescence spectrum of 2-naphthoI molecules during the sol-gel-xerogel transitions was almost unchanged (Fujii, 1990). Therefore, the fluorescence spectrum of 1-naphthol molecules is a useful photophysical probe. The probe was used in the sol-gel-xerogel transition systems ofmixed aluminum and silicon oxides system (Fujii, 1992, 1997). Hydrogen-bonded forms and contact ion pair forms are considered for the interaction species formed between 1-naphthol and the gel surface. 

Trends in Photochem. Photobiol. 1994 3 243-260 Fujii T., Mishima S., Kawauchi O. Effects of Si-Al composition on the fluorescence spectra of 1-naphthol during the sol-gel-xerogel transitions. Res. Chem. Intermed. 1997 23 143-154 Fujii T., Kodaira K., Kawauchi O., Tanaka N., Yamashita H., Anpo M. Photochromic behavior in the fluorescence spectra of 9-anthrol encapsulated in Si-Al glasses prepared by the sol-gel method. J. Phys. Chem. B 1997 101 10631-10637... 

Kamitani K., Uo M., Inoue H., Makishima A. Synthesis and spectroscopy ofTPPS-doped silica gels by the sol-gel process. J. Sol-Gel. Sci. Tech. 1993 1 85-92 Kaufman V.R., Avnir D. Structural changes along the sol-gel-xerogel transition in silica as probed by pyrene excited-state anission. Langmuir 1986 2 717-722 Kaufman V.R., Levy D., Avnir D. A Photophysical study of the sol/gel transition in silica structural dynamics and oscillations, room-temperature phosphorescence and photochromic gel glasses. J. Non-Cryst. Solids 1986 82 103-109... 

Mann S., Bnrkett S.L., Davis S.A., Fowler C.E., Mendelson N.H., Sims S.D., Walsh D., Whilton N.T. Sol-gel synthesis of organized matter. Chem. Mater. 1997 9 2300-2310 Matsni K., Matsuzuka T., Fujita H. Fluorescence spectra of 7-azaindole in the sol-gel-xerogel stages of silica. J. Phys. Chem. 1989 93 4991 994... 

The Use of Trapped Molecules for Mechanistic Studies of the Sol-Gel-Xerogel Transitions and of the Cage Properties... 

Aniline, intercalation in layered protonic conductors, 220-229 Aromatic polycyclic molecules, use as probe molecules for mechanistic studies of sol-gel-xerogel transitions and cage properties, 400 Artificially layered ceramics, nanoscale, electrodeposition, 244-253 Asymmetrically layered zirconium I iqtonates, 166-176 experimental procedure, 174-176 interlayer spacings of compounds, 170r schematic representations of layers, 169/ synthesis, 167-168... 

---