Abstract
Five novel europium(III) complexes with 2-[4-(dibutylamino)-2-hydroxybenzoyl]benzoic acid (DAHB) as primary ligand and bathophenanthroline (batho), 2,2’-bipyridyl (bipy), 5,6-dimethyl-1,10-phenanthroline (dmph), 1,10-phenanthroline (phen) as ancillary ligands were synthesized via solution precipitation method. The structural formulae of synthesized complexes were speculated to be Eu(DABH)3·2H2O (C1), Eu(DABH)3·batho (C2), Eu(DABH)3·bipy (C3), Eu(DABH)3·dmph (C4) and Eu(DABH)3·phen (C5) by elemental analysis, infrared spectroscopy and proton nuclear magnetic resonance spectroscopy (1H-NMR). The photoluminescent properties and thermal stability of the complexes were investigated by photoluminescent spectroscopy and thermogravimetric analysis (TG-DTG), respectively. The Commission Internationale de I’ Eclairage (CIE) color coordinates, Judd–Ofelt intensity parameter (Ω2), total quantum yield, intrinsic quantum efficiency and energy transfer dynamics of complexes were also explored. The excitation spectra of complexes are extended up to visible region. These complexes exhibit characteristic photoemission of Eu3+ metal ion with high color purity in red region attributed to efficient energy transfer from ligand to metal ion. The replacement of water molecules from coordination sphere of europium ion by ancillary ligands results in enhancement of luminescent properties of the C2–C5 complexes, indicating that ancillary ligands act as additional light harvesting centers in sensitization phenomenon. The thermal studies show that these complexes are suitable for meeting the requirement of temperature for fabrication of OLEDs devices.