Rare earth (Eu3+, Tb3+) centered composite gels Si–O–M (M = B, Ti) through hexafluoroacetyl-acetone building block: Sol–gel preparation, characterization and photoluminescence

This report focuses on the syntheses of a series of novel photoactive composite xerogels materials in which the functionalized hexafluoroacetylacetone (HFAASi) organic components are grafted into the different inorganic networks (SiO2–B2O3 or SiO2–TiO2) via covalent bonds through a sol–gel process. Subsequently, the physical characterization and especially photoluminescent properties of the resulting xerogel materials are studied in detail. Except for composite xerogels linked to SiO2–TiO2 networks, all of these composite xerogels exhibit homogeneous microstructures and morphologies, suggesting that molecular-based materials are obtained with strong covalent bonds between the organic β-diketone ligand and inorganic matrices. In addition, the ternary rare earth composite gels present stronger luminescent intensities, longer lifetimes, and higher luminescent quantum efficiencies than the binary ones, indicating that the introduction of the second ligands (phen) can sensitize the luminescent emission of the rare earth ions in the ternary hybrid systems. It should be especially noted that these composite xerogels based on Si–O–B networks possess not only higher thermal stability but also stronger luminescent intensities than the other systems linked to different inorganic networks.

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► Composite gel of Si–O–M (M = B, Ti).
► Hybrids with Si–O–B possess favorable luminescence property.
► Sol–gel process of different alkoxides.