Síntese, caracterização e estudo fotofísico de compostos de coordenação contendo os íons európio, térbio e samário e o ligante ácido 4,4- sulfonildibenzóico

Abstract

The abundance and wide applicability of lanthanides increases interest and the search for new coordination compounds containing these ions. Therefore, the objective of the work was to synthesize coordination compounds involving lanthanide ions for subsequent study of their photoluminescent properties. Eight compounds were obtained using the 4,4- sulfonyldibenzoic ligand, of which seven were polycrystalline compounds whose structures could be proposed based on characterizations performed. These characterizations included vibrational spectroscopy in the infrared region and Raman spectroscopy, elemental analysis (C, H, N) and thermal analysis (TG) and then it can be inferred that the Eu3+ and Sm3+ compounds are isostructural. The other compound crystallized in the form of a single crystal, whose structure was elucidated by the single crystal X-ray diffraction. The structure contains two crystallographically independent Eu3+ metal centres, which coordinate in a bidentate bridging manner to four of the 4,4-sulfonyldibenzoic acid ligand. Despite using the same metals and ligand, different compounds were obtained by modifying the synthetic methodology. Photoluminescence spectroscopy of the polycrystalline compounds was carried out, and excitation, emission and lifetime spectra were obtained. From their analysis, it was confirmed that an excellent structural proposal for the compounds was achieved. Information such as radiative and non-radiative decay, quantum efficiency, and chromaticity diagrams were obtained, indicating a purity of emission for the Eu3+ compounds.