Photoactive lanthanide (Eu3+, Tb3+) centered hybrid systems with titania (alumina)-mesoporous silica based hosts

Abstract

1-(2-Naphthoyl)-3,3,3-trifluoroacetonate (NTA) functionalized SBA-15 mesoporous hybrid material (NTA-S15) was synthesized by co-condensation of modified NTA (denoted as NTA-Si) and tetraethoxysilane (TEOS) in the presence of Pluronic P123 surfactant as a template. Then, nicotinic acid (NA) was selected as the second ligand, whose carboxylic acid group can react with metallic alkoxide to moderate the reactivity towards hydrolysis and condensation, and the heterocyclic group can coordinate to lanthanide ions as well as sensitize their luminescence. Finally after the coordination reaction between lanthanide ions and a functionalized organic ligand (NTA-S15 and NA-M (M = Ti, Al)) and the hydrolysis cross-linking reaction, the final mesoporous hybrids Ln(NA-M)2(NTA-S15)3 (Ln = Eu, Tb; and M = Ti, Al) were obtained. FTIR, SAXRD, SEM, TEM, N2 adsorption measurements, photoluminescent spectra, and TG plots were characterized, and the results reveal that they all have high surface area, uniformity in the mesostructure, and good crystallinity. In addition, the hybrid materials Ln(NA-Al)2(NTA-S15)3 show an overall increase in luminescent lifetime and quantum efficiency compared to the mesoporous hybrid Ln(NA-Ti)2(NTA-S15)3, indicating that the Al–O network is a better host material for the lanthanide complex than the Ti–O network.