Luminescent lanthanide(III)-cored complexes based on the combination of 2-(5-bromothiophen)imidazo[4,5-f][1,10]phenanthroline and 2-thenoyltrifluoroacetonate ligands

A family of ternary beta-diketonate lanthanide(III)-cored complexes based on the combination of 2-(5-bromothiophen)imidazo[4,5-f] [1,10] phenanthroline (5-Br-TIP)/2-thiophenimidazo[4,54][1,10]phenanthroline (TIP) and 2-thenoyltrifluoroacetonate (TTA) ligands have been described herein, i.e. Ln(TTA)(3)(5-Br-TIP) [Ln = Eu (1), Dy (2), Er (3), Tb (4), Sm (5), Yb (6)] and Eu(ITA)(3)(TIP) (7). According to the fluorescence spectra of complexes 1, 3, 5, 6 and 7, characteristic luminescence of the Ln(3+) ions in the visible and near-infrared band ranges is observed, which is attributed to efficient energy transfer from the ligands to the metal centers. The room-temperature luminescence intensity of 7 is analogous to that of the strong fluorescent complex Eu(TTA)(3)(phen), but the fluorescence intensity of 1 is much weaker. In addition, complexes 1 and 7 show 1.1 and 1.4 times greater fluorescence intensity at 77 K compared with the fluorescence spectra at room temperature. (C) 2013 Elsevier Ltd. All rights reserved.