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 (H 2 O) x (x = 3, for Eu 3+ and Gd 3+ , and x = 4 for Tb 3+), 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 5 D 0 emitting level of the Eu 3+ 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.

Promoting a Significant Increase in the Photoluminescence Quantum Yield of Terbium(III) Complexes by Ligand Modification

“…To circumvent the low extinction coefficients and enhance the luminescent properties of the 4f ions, several complexes of Tb 3+ , as well as other trivalent lanthanide ions (Ln 3+ ) such as Sm 3+ , Eu 3+ , and Dy 3+ , have been synthesized with chelating, strongly absorbing multidentate organic ligands, especially those containing aromatic or other π-chromophores such as β-diketonates, bipyridines, calixarenes, and dipicolinic acids that display the so-called “antenna effect”. ,− This gives highly luminescent complexes in which, following irradiation by UV light and according to the widely known Jablonski model, the chromophore-containing ligand transfers energy to the metal center via the ligand first excited triplet state (T 1 ), populating the emitting Ln 3+ levels. , In addition to this, the importance of the so-called “singlet pathway”, in which the energy transfer to the 4f levels occurs directly from the ligand first excited singlet state (S 1 ), has also been recognized, although the longer-lived T 1 state is generally accepted as the most suitable intermediate …”

Síntesis y caracterización luminiscente y magnética de partículas multifuncionales de YBCO@OT

“…que una diferencia de energía "segura" entre el estado triplete del ligando orgánico y el nivel emisivo 5 D j de los iones Ln (III) debe estar entre 2,500-3,000 cm −1 para una eficiente transferencia de energía (TE) [153]. Sin embargo, en algunos casos dicho valor es menor (2,100 cm −1 ) [186,187,300,301] operando la Transferencia de Energía Inversa (TEI) cuando la energía del estado triplete es muy similar a la del nivel emisivo Ln 3+ [153]. Dado que el nivel emisivo 5 D 2 de los iones Eu 3+ se encuentra 1,200 cm −1 por debajo del estado triplete del ligando oxalato, dicha diferencia de energía no se cumple, produciendo así la fosforescencia del ligando (consultar Apéndice D) [153,[187][188][189].…”