Abstract
Composites containing chlorophyll aggregates dispersed in amorphous silica are of interest because of their optical attractive properties. The silica powders added with chlorophyll species, prepared by the sol-gel method, were studied using X-ray diffraction, IR spectroscopy and differential temperature analysis. Silica xerogel samples were prepared using an ethanol/H2O/TEOS molar ratio of 4:11.6:1 and loaded with extracts from frozen spinach leaves. The silica xerogel microstructure of the powders was studied as a function of the annealing temperature. We found in our samples partial crystallization of the glass matrix in form of tridymite and cristobalite phases and quenching centers or nonfluorescing aggregates due to denaturation of photosystem promoted by chlorophyll decomposition after400∘C.
Highlights
Sol-gel chemistry and further processing to xerogels or aerogels allow flexibility in obtaining a great variety of materials based on incorporation of particles embedded in inert matrices such as SiO2 with specific properties, which are related to the structure of the forming composite materials
It is necessary to understand the structural evolution of extracted components of leaves embedded in silica xerogel matrix, as well as the interaction between the pigments embedded into the inorganic matrix under heat treatment in which the matrix undergoes a gel to glass transition, and correlate all these changes with the optical properties
We compared the spectral characterization of chlorophyll fluorescence of the doped glass and the structural evolution promoted by heat treatment with the spectral characterization of chlorophyll fluorescence of pure barley
Summary
Sol-gel chemistry and further processing to xerogels or aerogels allow flexibility in obtaining a great variety of materials based on incorporation of particles embedded in inert matrices such as SiO2 with specific properties, which are related to the structure of the forming composite materials. These matrices have been used experimentally as supporting substrates for molecular chemical systems [1] and for artificial photosynthesis [2, 3]; including organic photoactive or electroactive molecules has opened new opportunities for optical and electrooptical applications [4,5,6,7]. We compared the spectral characterization of chlorophyll fluorescence of the doped glass and the structural evolution promoted by heat treatment with the spectral characterization of chlorophyll fluorescence of pure barley
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