Síntese, caracterização e estudo fotoluminescente de redes metalorgânicas contendo íons lantanídeos (LnOFs)

Abstract

In this work, metal-organic frameworks (LnOFs) containing lanthanide ions were obtained, focusing on the characteristic luminescent properties of this series of metals, which make them promising for applications in sensors, light-emitting devices, among others. The LnOFs were synthesized via hydrothermal methods, using the ligands 2,5-thiophenedicarboxylate (TDC) and 2,5-furandicarboxylate (FDC) in combination with sodium oxalate (ox), in the presence of Eu³⁺, Tb³⁺, and Gd³⁺ ions. The synthesized materials were characterized by infrared absorption spectroscopy, Raman scattering spectroscopy, powder X-ray diffraction, and single-crystal Xray diffraction. The analyses revealed the formation of two novel compounds, [Eu₂(TDC)₂(ox)(H₂O)₄]·H₂O and [Tb₂(TDC)₂(ox)(H₂O)₄]·H₂O, which crystallize in the P2₁/c and C2/c space groups, respectively. The compound [Gd₂(TDC)₂(ox)(H₂O)₄]·H₂O, previously reported in the literature, was also obtained and used as a structural reference in this study. Elemental analysis (CHN), thermogravimetric analysis, crystal structure determination, and photoluminescence analysis were carried out. The latter showed that the compounds exhibit characteristic emissions, with Eu³⁺ emitting in the red region and Tb³⁺ in the green region. Although the focus was on the novel compounds, several syntheses were performed, including previously reported structures, to allow a broader comparison of the structural and luminescent behavior within the series.