Exploring the influence of emissive centers in mono and dinuclear europium(III) complexes for advance lighting applications: Synthesis, characterization and computational modelling

The combination of 4,4,4-trifluoro-1-phenyl-1,3-butanedione (TFPB) and pyrazine (pyz) with Eu³⁺ ions results in the formation of two distinct types of complexes, characterized by general formulae [Eu(TFPB)₃(L)₂] (here, L is either H₂O or pyrazine) and [(Eu(TFPB)₃)₂pyz]. The impact of surrounding environment on the photophysical properties of synthesized complexes was thoroughly examined. Photoluminescence (PL) analysis revealed the dominance of electric dipole (ED) transition (⁵D₀→⁷F₂) in these complexes. Theoretical calculations via Judd-Ofelt analysis were also performed. These complexes exhibit visible luminescence in both solid and solvated forms. Notably, the luminescence intensity of prepared dinuclear complex is found to be manifolds greater than its mononuclear analogues, affirming the contribution of both metal centers towards emission intensity. Furthermore, the absence of ligand centered emission in prepared complexes suggests the effective energy transfer from coordinated moieties to metal center. CIE color coordinates of prepared Eu(III) complexes, in both solid and solution media, exhibited intense red emission. DFT calculations were conducted to elucidate the distribution of electronic density in synthesized complexes. Additionally, a comprehensive analysis of these complexes, including IR, UV, NMR, thermogravimetry and cyclic voltammetry was conducted.