Photoluminescence of Nanostructured Bridged Silsesquioxanes Containing Urea Groups Doped with Safranine-O

MARÍA L. GÓMEZ (*); DIANA P. FASCE; ROBERTO J. J. WILLIAMS; HERNÁN A. MONTEJANO; CARLOS M. PREVITALI

Corfu, Grecia

Simposio; IIIrd INTERNATIONAL SYMPOSIUM ON NANOSTRUCTURED AND FUNCTIONAL POLYMER-BASED MATERIALS AND NANOCOMPOSITES; 2007

Bridged silsesquioxanes are a family of organic-inorganic hybrid materials prepared by the hydrolysis and condensation of monomers containing an organic bridging group joining two (or eventually more) trialkoxysilyl or trichlorosilyl groups. The organic group, covalently bonded to the trialkoxysilyl groups, can be varied in composition, length, rigidity and functionalization. This determines its contribution to the properties of the crosslinked material. Bridged silsesquioxanes bearing urea groups have received considerable attention in recent years due to their capacity of self-structuration through H-bonds and their white-light photoluminescence.1,2 The aim of this study was to extend our previous research on the photoluminescence of a bridged silsesquioxanes synthesized by the hydrolysis and condensation of a precursor based on the reaction of 4,4’-[1,3 phenylenebis-(1-methylethylidene)]bis(aniline) (BSA) end-capped with 3-isocyanatepropyltriethoxysilane (IPTES).2 Nanostructuration was confirmed by the presence of a correlation peak in SAXS spectra at q = 0.23 Å-1 determining a correlation distance of 27 Å between inorganic clusters that corresponds to the length of the organic bridge.2 Safranin-O was selected as a convenient photoluminescent molecule to dope the bridged silsesquioxane. Similarly to BSA it has 2 aromatic amine groups that may be end-capped with IPTES leading to an urea type precursor. Structures of urea bridges based on BSA and Safranin-O are shown in Figure 1.