Síntese e caracterização de complexos de Eu(III), Tb(III), Sm(III) e Gd(III) com ligantes carboxilatos, betadicetonatos e nitrogenados

Abstract

In this work, the synthesis and characterization of new lanthanide complexes with betadicetonates, carboxylates and neutral nitrogenous ligands, that can possible act as Light Conversor Molecular Devices (DCMLs), were performed. Four series of compounds were obtained: Tb(III), Eu(III) and Gd(III) ions with 4,4,4-trifluoro-1-phenyl-1,3-butanedione (TFB) and terephthalic acid (TPA). These syntheses generated two different types of complexes: for Tb(III) the coordination occurred with only one of the ligands and Gd(III) complexed with the two ligands and then formed a monocrystal with the TFB. Using the Eu(III) ion, it was observed the formation of a complex with the two ligands. The other series of Tb(III) complexes synthetized with the ligands 2-tenoyltrifluoroacetone (HTTA) and terephthalic acid (TPA), presented coordination only with TPA. The third series of compounds that were obtained using Eu(III), Tb(III), Sm(III) and Gd(III) with 2-furoic acid (ACF) and 4,4-dimethyl-2,2-bipyridine (DBP) have a molecular formula of [Ln2C44H36O18N6]. The last series of compounds obtained by the coordination of 3-thiophene acetic acid (TIO) and 4,4-dimethyl-2,2-bipyridine with the ions Tb(III), Eu(III) and Gd(III) presented a molecular formula of [Ln2C60H60O12N4S6]. These complexes were characterized by infrared, Raman, elemental analysis and single crystal or powder X-ray diffraction. The luminescent properties of the complexes synthetized as the intensity parameters of Judd-Ofelt (for Eu(III) complexes), lifetime, radiative and non-radiative decay rate, and quantum efficiency were obtained by radiative decay curves and by the emission and excitation spectra of the complexes. The triplet state, T1, of the ligands was obtained by the time resolved phosphorescence spectrum of each Gd(III) complex. In addition, it was observed that the [Eu2C44H36O18N6] and the [Eu2C60H60O12N4S6] complexes have a quantum efficiency of 54.52 and 45.42%, respectively, suggesting that these complexes can act as luminescent devices.