Lanthanide-based coordination compounds of molecular formula [Ln(keto) 3 (H 2 O)], where Ln¼ Gd, Eu and keto¼ ketoprofen, were synthesized and their photoluminescence features were detailed in the 12-300 K interval. The emission spectra of [Eu(keto) 3 (H 2 O)] reveal a strong dependence with the temperature, well-illustrated by an unusual large blue-shift (∼17 cm À 1) of the 5 D 0-7 F 0 transition as the temperature is raised. The arithmetic difference between the absorption spectrum of [Eu(keto) 3 (H 2 O)] with that of [Gd(keto) 3 (H 2 O)] pointed out the presence of a ligand-to-metal charge transfer (LMCT) band (320-370 nm). From the [Gd(keto) 3 (H 2 O)] phosphorescence the energy of the keto-related triplet states was determined showing a large overlap with the intra-4f 6 levels and a strong electron-phonon coupling. The high-resonance between the LMCT and triplet states and the Eu 3 þ levels leads to a strong dependence of the 5 D 0 lifetime value, typical of the presence of operative energy transfer processes.

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Mesoporous silica nanoparticles prepared by organic template-driven synthesis have been successfully explored as carriers of the drug-derivate green luminescent complex of terbium (III) with the nonsteroidal anti-inflammatory drug ketoprofen. The terbium (III) complex was synthesized by reacting ketoprofen sodium salt with terbium (III) chloride, which was further adsorbed onto the surface of mesoporous nanoparticles with a mean particle size of 47 ± 4 nm and pore size of 11 nm. The incorporation of the complex into mesoporous silica nanoparticles was tracked by the decrease in the surface area and pore size of the nanoparticles, and successfully demonstrated by substantial changes in the adsorption isotherms and thermal and vibrational spectroscopy results. The cytotoxicity assay and confocal microscopy have shown that the novel luminescent nanohybrid presents high cell viability and the characteristic terbium (III) emission can be assessed through two-photon excitation, which paves the way for bioimaging applications in nanomedicine.

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