Preparation and characterization of a gadolinium compound with high thermal stability

A new lanthanide compound [Gd(2,5-HPA)(2,5-PA)]n (1; 2,5-H2PA = 2,5-pyridinedicarboxylic acid) was obtained through hydrothermal reactions and structurally characterized by single-crystal X-ray diffraction. It possesses a three-dimensional (3-D) framework structure. Solid-state photoluminescence experiment revealed that it shows dark blue emission band, which can be assigned to the characteristic emission of the 4f electron intrashell transition of 6P7/2 → 8S7/2 (Gd3+). The energy transfer mechanism was explained by an energy level diagram of the gadolinium ion and 2,5-pyridinedicarboxylic acid ligand. It displayed remarkable CIE chromaticity coordinates of 0.1346 and 0.0678. The solid-state UV/Vis diffuse reflectance spectra unveiled that it possesses a wide optical band gap of 3.52 eV. Thermogravimetry (TG) measurements revealed that this compound is highly thermal stable up to around 500 °C.                     KEY WORDS: CIE, Energy transfer, Lanthanide, Photoluminescence, Thermal stability   Bull. Chem. Soc. Ethiop. 2020, 34(3), 479-488. DOI: https://dx.doi.org/10.4314/bcse.v34i3.