| Abstract
| - A series of substituted triarylmethylium cations,including malachite green,tris(4-methoxyphenyl)methylium,and bis(4-methoxyphenyl)phenylmethylium cations, has beenprepared adsorbed on tridirectional large pore zeolitesY and β in their H+ or La3+ form, as wellas within the novel mesoporous aluminosilicate MCM-41, byship-in-a-bottle synthesis from the corresponding benzaldehyde andN,N-dimethylaniline or anisole. Theresulting compositesexhibit diffuse reflectance and IR spectra characteristic of thesetrityl dyes. The cation content was determined bythermogravimetry−differential scanning calorimetry. Preparationof these triarylmethylium cations exclusively onthe external surface of ZSM-5, a medium pore zeolite whose internalvoids are too small to accommodate thesecations, is also possible. Therefore, the methodology based in thediffusion of smaller precursors does not guaranteeitself the intrazeolite location of the synthesized guests. Inthis work, we have experimentally determined that thedyes are blocked in the interior of the faujasite pores. Thus,direct evidence showing the location of the organicmaterial inside the zeolite supercages was obtained using X-raydiffraction and X-ray photoelectron spectroscopy.These dyes incorporated within microporous solids can act asheterogeneous photosensitizers to promote the sensitizeddimerization of 1,3-cyclohexadiene.
|
