SÍNTESE, CARACTERIZAÇÃO E ESTUDO DOS PARÂMETROS DE JUDD-OFELT DE COMPOSTOS β‑DICETONATOS DE Eu(III) OU Sm(III)

• Autor(a) principal: Scapolan,Maria I. X.
• Data de Publicação: 2021
• Outros Autores: Oliveira,Daniel H. de, Monteiro,Jorge H. S. K., Davolos,Marian R., Adati,Renata D.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Química Nova (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422021001001261
• topic: lanthanide β-diketonates; photoluminescence; Sparkle Model; Judd-Ofelt parameters

The lanthanide complexes [Ln(bmdm)3(L)] where Ln(III) = Eu and Sm were synthesized successfully using the diketone (1-(4-methoxyphenyl)-3-(4-tert-butylphenyl) propane-1,3-dione) (bmdm) and (L) = 1,10-phenanthroline (phen), 2,2’-bipyridine (bipy) ligands. The coordination modes were determined as bidentate chelate by the FT-IR. The ground state geometry was determined using the Sparkle/AM1 implemented in MOPAC2016 package. Europium complexes exhibit the characteristic emission bands that arise from5D0→7FJ (J = 0-4); the presence of just one5D0→7F0 line transition means that this site is without the center of inversion. Samarium complexes display transitions at4G5/2→6HJ (J = 5/2; 7/2; 9/2 and 11/2), being the4G5/2→6H9/2 the most intense, indicating that the forced electric dipole mechanism is predominant when compared with the magnetic dipole ones. The intensity parameters Ω2 and Ω4 were calculated according to the emission spectra for Eu(III) and absorption spectra for Sm(III). The high Ω2 values demonstrated that the lanthanide ion in bipy or phen complexes is in a highly polarizable chemical environment. The emission lifetime (τ) increases compared with that of precursor aquo complexes, confirming that the non-radiative quenching is minimized. The low quantum efficiency is a result of NIR emissions and non-radiative transitions of Sm(III).