Structural Investigation of the Hydrolysis-Condensation Process of Titanium Alkoxides Ti(OR)(4) (OR = OPri 2, OEt) Modified by Acetylacetone. 2. From the Modified Precursor to the Colloids

Y The modified precursor Ti(OPri)(3)acac (acac = acetylacetonate) has been successfully used to prepare, via a sol-gel route, stable TiO2-based colloids over a wide pH range. The hydrolysis-condensation process was investigated by using infrared, H-1 NMR, and X-ray absorption spectroscopies (XANES-EXAFS). The alkoxy groups are quickly removed during the hydrolysis while acetylacetonato groups still remain bound to titanium even when large amounts of water are present. The final colloids show structural data close to TiO2 anatase. However, due to the presence of acetylacetonato groups, they exhibit quite unusual photochemical properties.