Luminescent properties and complex formation of lanthanide ions with pyromellitic acid

Synthesis of complex compounds of ۱,۲,۴,۵-benzentetracarboxylic acid (pyromellitic) with ions of samarium (III), europium (III), gadolinium (III), terbium (III) was carried out composition and structure of the complexes were studied by the methods of elemental, IR spectroscopic and differential thermal analysis. According to the data of elemental analysis and thermogravimetry, the obtained complexes are hydrated to the composition Ln۴L۳ nH۲O, where n=۲. The region of their thermal stability is within the range from ۱۰۰°C to ۱۵۰°C. Electronic and infrared absorption spectra of the ligand and complexes with ions of rare earth metals were measured. According to the IR spectra, coordination of the ligand with the metal ion occurs via the carboxyl group. The carboxyl group is coordinated bidentately. To excite luminescence, the line of a mercury lamp with a wavelength of ۲۴۸ nm was used. The highest luminescence intensity is observed for the coordination compounds Sm+, Eu۳+, Gd۳+, and Tb۳+. This suggests identical luminescence center symmetry and, consequently, a similar coordination unit of structure. Electron microscopy also revealed that the polymeric materials are transparent and luminesce red when irradiated with ultraviolet light. Electron microscopy revealed an uneven distribution of complex compound particles in this sample. The luminescence spectra of these materials are identical to those of the individual complex compounds, indicating preservation of the structure of the dispersed particles in the polymeric luminescent complex compounds.

کلیدواژه ها:

complex compounds ، Rare-earth Elements ، Thermogram ، IR spectra ، luminescence