This work deals with the fluorescence behavior exhibited by extracts of parota wood (enterolobium cyclocarpum) when are embedded in a silica matrix, and the effect of the temperature on the emission and structural properties. The organics were incorporated into a silica matrix using the sol-gel method, and the resulting hybrid composite was subjected to different heat treatments to study its thermal stability and the effect on their structural and fluorescence properties. The structural properties were studied using x-ray diffraction (XRD), and the organics were analyzed by infrared spectroscopy (FT-IR) and fluorescence spectroscopy. Results show that the silica matrix avoids the thermal decomposition of the organics, and the structural changes of the silica impact on the fluorescence properties. In this sense, the maximum emission obtained at 400 °C was three times higher than the RT. This behavior was attributable to the strong interactions between the cellulosic compounds and the silica. Also, the cellulosic compounds promote the formation of open Si-O arrangements.

Thermostructural and fluorescence properties of enterolobium cyclocarpum extract embedded in a silica xerogel matrix

Effect of xanthyletin on the structural and fluorescence properties of a silica-based hybrid composite

This work deals with the carminic acid stabilization in a silica matrix and the study of structural properties. Results indicate that silica provides exceptional thermal stability to the carminic dye because its functional properties remain without significant changes up to 500 °C. The embedded carminic acid changes the crystallization behavior of silica. The carminic acid extracted from Mexican cochineal was firstly stabilized with sucrose and after embedded in a silica matrix using the sol-gel method. The structural behavior was analyzed in function of temperature from RT to 900 °C. The resulting properties were studied using X-ray diffraction and FT-IR spectroscopy. Interaction of carminic acid with silica reduces the formation temperature of tridymite and cristobalite. Amorphous tridymite was detected at 400 °C, semicrystalline tridymite at 700 °C, α-cristobalite at 800 °C, and β-cristobalite at 900 °C. The improved stability of carminic acid results from its interaction with the silica, which also modifies the silica crystallization kinetics.

A. M. Herrera-González

Papers

Thermostructural behavior of red cochineal dye stabilized with sucrose and embedded in a silica xerogel matrix

Thermostructural and fluorescence properties of enterolobium cyclocarpum extract embedded in a silica xerogel matrix