Ariel Guzmán

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.

Highly Basic and Dipolar Layered Double Hydroxides Enhance Catalysis of Cyanoethylation of Alcohols

Layered double hydroxides (LDH), magnesium–aluminum–carbonates and magnesium–gallium–aluminum–carbonates, were synthesized by sol–gel incorporating during synthesis a part of aluminum as (AlF6)3− blocks in order to incorporate F− as a part of brucite-like layers and not as compensating anions. Structural, textural and surface properties of resulting fluorinated were characterized. Particularly, presence the fluorine as a part of brucite-like layers influenced directly polarity and hydrogen bonding acceptor character at surface of materials. These modifications at surface of LDH greatly changed their catalytic properties. Cyanoethylation reaction between acrylonitrile and methanol was catalyzed by both fluorine-free and fluorinated LDH, pointing out a clear influence of fluorine on the conversion and rate reaction.Graphical Abstract