Spectroscopic, luminescence and in vitro biological studies of solid ketoprofen of heavier trivalent lanthanides and yttrium(III)

Solid-state compounds of the general formulae [ML3] (M = Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y; L = ketoprofen) were synthesized and characterized using infrared, diffuse reflectance and luminescence spectroscopies. IR data suggested that the carboxylate group in ketoprofen is coordinated to the metals as a bidentate ligand. The triplet state energy level was determined using the Gd3+ complex, which exhibited a ketoprofen blue luminescence when excited in the UV region. The compound containing Tb3+ ion was sensitized by the ligand and emitted in the green region of the visible spectrum. On the other hand, for the analogous species containing the dysprosium ion, a competition for luminescence between the Dy3+ and the ligand levels was observed. Finally, Tm3+ complex exhibits only ligand luminescence. These optical behaviors are discussed based on rare earth energy diagrams. In addition, the compounds were evaluated for their anti-inflammatory activities. All the compounds showed a higher production of H2O2 and IL-10 than the ketoprofen, suggesting that the compounds exhibited an immunomodulatory effect and this opens up new perspectives for immunotherapeutic approaches. (C) 2014 Elsevier Inc. All rights reserved.