Síntese e estudo das propriedades fotoluminescentes de novos complexos β-dicetonatos do íon Eu3+ com o ligante 2-(1,3-dioxoisoindolin-2-il)-n-(piridin-2-il) acetamida

• Ano de defesa: 2021
• Autor(a) principal: Queiroga, Anna Paula Rocha de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraíba; Brasil; Química; Programa de Pós-Graduação em Química; UFPB
• Palavras-chave em Português: Luminescência; β-dicetonas; Amidas como ligantes; Transferência de energia.; Luminescence; β-diketones; Amides as ligands; Energy transfer; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/123456789/20247

The coordination compounds of trivalent lanthanide ions are widely studied due to their peculiar photophysical properties that allow their use in several applications. To this end, it is of utmost importance to study and determine ligand that are efficient for the luminescence sensitization process of these ions. With this in mind, this study reports the synthesis of a new class of complex tris β-diketonates of the Eu3+ ion and its Gd3+ analogues with the compound 2-(1,3-dioxoisoindoline-2-yl)-N-(pyridin-2-yl)acetamide (fg2ap) as an auxiliary binder, aiming to investigate its photoluminescent properties. The auxiliary ligand amide was initiated from the reaction between 2-aminopyridine and N-phthaloylglycine chloride in a yield of 56,18%. The determination of ligand synthesis was made by melting point data, absorption spectroscopy in the infrared region and 1H and 13C nuclear magnetic resonance. The complexes, on the other hand, were synthesized by replacing the water molecules of the hydrated tris β-diketonate complexes with the amide ligand fg2ap, presenting yields of 26 to 83%. These were characterized by complexometric titration, spectroscopy in the infrared region, thermogravimetric analysis and had their spectroscopic properties were analyzed experimentally, as well as geometries and absorption spectra investigated from computational modeling. The data captured by complexometric titration and thermogravimetric analysis suggest that the complexes have a general formula [Ln(β-dic)3(fg2ap)], and the coordination of the β-dicetonate ligands occurs through the oxygen atoms of the carbonyl groups and the auxiliary ligand amide by means of one of the carbonyls and heterocyclic nitrogen, according to the absorption spectra in the infrared region. The replacement of water molecules by this amide in the Eu3+ ion complexes increases the intrinsic quantum yields of luminescence and the triplet states determined experimentally through the emission spectra of the Gd3+ complexes, as well as, according to the TDDFT calculations of excited states, indicate favorable resonance conditions between the lowest energy triplet states of the ligands with the 5D0 emitter level of the Eu3+ ion.