Spectra of orthosilicates

The fluorescence spectra of 9-anthrol (58) were studied in the sol-gel-xe-rogel transitions of Si-Al glasses of various composition prepared from tetraethyl orthosilicate and diisobutoxyaluminium triethylsilane [205], A biprotonic ESIPT between the anthrone and anthrol tautomers was observed in which a proton of the surface Brpnsted acid site on the —O—Si—O—A1—O— network was implicated. 

Piriou, B., and P. McMillan (1983). The high-frequency vibrational spectra of vitreous and crystalline orthosilicates. Amer. Mineral. 68, 426-43. 

E. M. Flanigen I would like to cite a recent reference on the Raman spectra of various silicates and aluminosilicates, W. P. Griffith, Raman Studies on Rock-Forming Minerals. Part I. Orthosilicates and Cyclo-silicates, J. Chem. Soc. (A) 1969, 1372. This author apparently experienced no difficulty in obtaining the Raman spectra with a He—Ne laser Raman. The particle size of the samples was not specified, but described as microcrystalline. ... 

A difference in the relationship between UCV and degree of substitution x has recently been reported in connection with the use of tetramethyl orthosilicate (TMOS) as the silicon source instead of TEOS. The Ti content can be increased up to a value of 0.05 without evidence for extra-framework titanium species in the UV-visible spectra. However the UCV increases do not follow the relationship of Eq. (5) and the maximum value obtained, 5390 A3 at x = 0.05, is the... 

EUROTS-1 was synthesized (150g) by hydrothermal treatment of a gel derived from ethyl orthosilicate and ethyl orthotitanate, in the presence of tetrapropyl-ammonium hydroxide as template [31]. Each participating laboratory performed its own calcination (3 h or 16 h at a maximum temperature of 823 K, other conditions being varible). The Ti content was 2.8%, and the calcined product consisted of a single phase of orthorhombic symmetry, with a BET surface area of 435 m2g . Its IR and diffuse reflectance spectra (DRS) have been recorded. The material had the form of small rounded cubes of about 0.15/im size. 

Mesoporous phosphomolybdic acid has been hydrotheimally synthesized with the surfaetant template cetyltrimethylammonium bromide, phosphomolybdic acid and tetraethyl orthosilicate as the silicon source. The parent materials are extracted in a solvent to remove the oi anic structuredirecting agent. The materials have been characterized by chemical analysis. X-ray diffraction, TEM, Infrared spectra and nitrogen BET surface measurement. After extraction of the silica-modified salts with HCI/EtOH, the surface area of the mesoporous material is up to 140 m /g, and the pore diameter is 30 40 nm. 

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