Intriguing light-emission features of ketoprofen-based Eu(III) adduct due to a strong electron–phonon coupling

• Published in: Journal of luminescence Vol. 170; pp. 357 - 363
• Main Authors: Lahoud, M.G., Frem, R.C.G., Gálico, D.A., Bannach, G., Nolasco, M.M., Ferreira, R.A.S., Carlos, L.D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-2016
• Subjects: 5D0 lifetime dependence with the excitation wavelength; Electron–phonon coupling; Ketoprofen; Lanthanide coordination compounds; 5D0 lifetime dependence with the excitation wavelength; Electron–phonon coupling; Lanthanide coordination compounds; Ketoprofen
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2015.08.050

Lanthanide-based coordination compounds of molecular formula [Ln(keto)3(H2O)], where Ln=Gd, Eu and keto=ketoprofen, were synthesized and their photoluminescence features were detailed in the 12–300K interval. The emission spectra of [Eu(keto)3(H2O)] reveal a strong dependence with the temperature, well-illustrated by an unusual large blue-shift (∼17cm−1) of the 5D0→7F0 transition as the temperature is raised. The arithmetic difference between the absorption spectrum of [Eu(keto)3(H2O)] with that of [Gd(keto)3(H2O)] pointed out the presence of a ligand-to-metal charge transfer (LMCT) band (320–370nm). From the [Gd(keto)3(H2O)] phosphorescence the energy of the keto-related triplet states was determined showing a large overlap with the intra-4f6 levels and a strong electron–phonon coupling. The high-resonance between the LMCT and triplet states and the Eu3+ levels leads to a strong dependence of the 5D0 lifetime value, typical of the presence of operative energy transfer processes.
•Luminescence characterization of [Eu(keto)3(H2O)] and [Gd(keto)3(H2O)].•Unusual large blue-shift (∼17cm−1) of the 5D0→7F0 transition, 12-300 K.•High-resonance between the LMCT and triplet states and the Eu3+ levels.•Strong electron–phonon coupling and strong dependence of the 5D0 lifetime value.