Gago, S, Fonseca IM, Parola AJ.
2013.
Hybrid mesoporous silica grafted with photoisomerizable 2-hydroxychalcones, 2013. Microporous and Mesoporous Materials. 180:40-47.
AbstractHybrid photochromic mesoporous materials based on MCM-41 and SBA-15 were synthesized by covalent attachment of 3'-butoxy-7-hydroxyflavylium (Fl-OH) and 3'-butoxy-7-metoxyflavylium (Fl-OCH3) hydrogensulfates. The pristine materials were initially grafted with 3-chloropropyl groups, reacted with 3'-hydroxyacetophenone and finally condensed with appropriate salicylaldehydes to yield the new hybrids MCM-41-Fl-OH and SBA-15-Fl-OCH3. The materials were characterized by powder X-ray diffraction, N-2 adsorption, solid-state C-13 CPMAS NMR spectroscopy, and thermogravimetric and elemental analyses, which confirm the successful covalent bonding of the flavylium moieties with loadings of 16.90 +/- 0.05% and 11.78 +/- 0.04% (w/w) for MCM-41-Fl-OH and SBA-15-OCH3, respectively. Flavylium compounds originate in solution a multiequilibria reaction network than can be actuated by pH and light, defining pH-coupled photochromic systems. The new hybrids show pH-dependent reflectance spectra resembling those observed in solution, but shifted to higher pH ranges, indicating a higher stability of the grafted flavylium cations. Irradiation of these materials equilibrated at adequate pH values where the photoisomerizable trans-chalcones predominate shows formation of the respective flavylium cations that recover back to the initial compositions upon standing in the dark, leading these new organic-inorganic hybrids as pH-dependent photochromic materials. (C) 2013 Elsevier Inc. All rights reserved.
Neves, CS, Granadeiro CM, Cunha-Silva L, Ananias D, Gago S, Feio G, Carvalho PA, Eaton P, Balula SS, Pereira E.
2013.
Europium Polyoxometalates Encapsulated in Silica Nanoparticles Characterization and Photoluminescence Studies. European Journal of Inorganic Chemistry. :2877-2886., Number 16
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Gomes, L, Marques A, Branco A, Araujo J, Simoes M, Cardoso S, Silva F, Henriques I, Laia CAT, Costa C.
2013.
IZO deposition by RF and DC sputtering on paper and application on flexible electrochromic devices. Displays. 34:326-333., Number 4
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