Aerogels made of chitosan and chondroitin sulfate, and containing 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin have been synthesized. The aerogels presented a microstructure made of microfibers and microsheets, with porosity higher than 99%. The dispersion and state of aggregation of the dye in the solids have been controlled with the aid of aromatic polyelectrolytes able to produce aromatic-aromatic interactions. Thus, non-homogenous dispersions of the dye as J-aggregates and formation of microcrystals on the microsheet surface were observed in the absence of the aromatic polymers; on the contrary, well dispersed H-aggregates of the dye were observed in the presence of poly(decylviologen), and well dispersed complexed monomeric dye molecules were found in the presence of a polyketone derivatized with hystamine, thus presenting imidazolium pendant groups. The same state of aggregation has been observed in solution for the respective complexes, highlighting the potential of aromatic-aromatic interactions to achieve a control of the state of aggregation of dyes in solution and further transfer to the solid state keeping their photophysical properties, and furnishing means for a good dispersion of the dyes in solid materials.
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