Rare earth-indomethacinate complexes with heterocyclic ligands: synthesis and photoluminescence properties

Abstract

In this work, synthesis, characterization and photophysical properties of trivalent rare earth complexes with a nonsteroidal anti-inflammatory drug [the indomethacinate (indo), presenting formulas RE(indo)(3)(H2O)(x) (x = 3, for Eu3+ and Gd3+, and x = 4 for Tb3+), RE(indo)(3)(bipy) and RE(indo)(3)(phen) (bipy: 2,2'-bipyridine, and phen: 1,10-phenanthroline)] were investigated. Based on photoluminescent results, the intramolecular energy transfer process from T-1 triplet states of indo, phen and bipy ligands to the D-5(0) emitting level of the Eu3+ ion in the coordination compounds is discussed. Accordingly, it is proposed two possible intramolecular energy transfer mechanisms between indomethacinate ligand and rare earth ions, which involve the participation of excited electronic states of the heterocyclic ligands as intermediate ones.