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

authors	Lahoud, MG; Frem, RCG; Galico, DA; Bannach, G; Nolasco, MM; Ferreira, RAS; Carlos, LD
nationality	International
journal	JOURNAL OF LUMINESCENCE
author keywords	Lanthanide coordination compounds; Ketoprofen; Electron-phonon coupling; D-5(0) lifetime dependence with the excitation wavelength
keywords	TEMPERATURE-MEASUREMENTS; SENSITIZED LUMINESCENCE; TRIVALENT LANTHANIDES; EUROPIUM(III) IONS; SOLID KETOPROFEN; IN-VITRO; COMPLEXES; FLUORESCENCE; LINEWIDTH; LIFETIMES
abstract	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 12-300 K interval. The emission spectra of [Eu(keto)(3)(H2O)] reveal a strong dependence with the temperature, well-illustrated by an unusual large blue-shift (similar to 17 cm(-1)) of the D-5(0)-> F-7(0) 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 (320-370 nm). From the [Gd(keto)(3)(H2O)] 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 Eu3+ levels leads to a strong dependence of the D-5(0) lifetime value, typical of the presence of operative energy transfer processes. (C) 2015 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE BV
issn	0022-2313
year published	2016
volume	170
beginning page	357
ending page	363
digital object identifier (doi)	10.1016/j.jlumin.2015.08.050
web of science category	Optics
subject category	Optics
unique article identifier	WOS:000367638500004