Hexagonal mesoporous silica material

Si 4H CP/MAS-NMR, 27A1 and 23Na MQ/MAS-NMR studies have been made of amorphous aluminium silicates, to determine local atomic struc-tures. A1 MAS-NMR (together with some other nuclei) studies have been carried out on novel porous sodium aluminophosphate-silicate and sodium ammonium fluorophosphates silicate 340 an ordered hexagonal mesoporous silica material (JLU-30) 341 mesoporous Al-MSU-X aluminosilicate 342 cubic mesoporous aluminosilicate A1MB48 343 and mesoporous Al-SBA-15.344... 

Photoisomerization of Azobenzene-Containing Dendrons in Nanostructured Silica. Zink and coworkers studied the photoisomerization of azobenzene-containing dendrons in 2-D hexagonal mesoporous silica materials (Sierocki et ah, 2006). Figure 13.13 shows a representative absorption spectra evolution of AzoGl (see Fig. 13.9) in dichloromethane in the dark after... 

Klotz, M., Ayral, A., Guizard, C. and Cot, L. (2000) Synthesis conditions for hexagonal mesoporous silica layers. Journal of Materials Chemistry, 10 (3), 663-669. 

As indicated by XRD patterns, there exist just 2-3 broad peaks in the calcined acid-made materials (Fig. 3A). Moreover, the N2 adsorption/desorption isotherm shown in Fig. 3B, the calcined acid-made mesoporous silica indeed possesses a broad capillary condensation at the partial pressure p/p0 of ca. 0.2-0.4, indicating a broad pore size distribution with a FWHM ca. 1.0 nm calculated from the BJH method. This is attributed to the occurrence of partial collapse of the mesostructure during the high temperature calcination. The hexagonal structure completely collapsed when subjected to further hydrothermal treatment in water at 100 °C for 3 h. Mesoporous silica materials synthesized from the acid route are commonly believed to be less stable than those from the alkaline route [6,7]. 

Figure 10 Preparation of solid sulphonic acid based on a hexagonal mesoporous silica. Key features of the materials are ...

Figure 16.2 Possible mechanisms of the formation of mesoporous silica materials, by generation of hexagonal silica-surfactant mesophases horn the interaction of silica precursor with (a) spherical micelles, (b) rod-like micelles, or (c) a preformed liquid crystalline phase of the surfactant.

---