Hybrid pigments resulting from several guest dyes onto γ-alumina host: A spectroscopic analysis

The synthesis of hybrid pigments was made from combination of γ-Al₂O₃ and some organic chromophores such as carminic acid, alizarin, purpurin, curcumin, fluorescein and betacyanins. The γ-Al₂O₃ was obtained through sol-gel synthesis with 2-propanol and aluminium tri-sec-butoxide (ATB). This article presents some spectroscopic evidences related to the formation of aluminium complexes between coordinative unsaturated sites (CUS) of aluminium and some organic groups (carboxylic acid, quaternary ammonium and β-keto enol) present in the chromophores structure. The physicochemical properties upcoming from a spectroscopic analysis point out that these materials can be applied in the design of new materials with potential uses in artworks and in the field of cultural heritage.