Optical properties of a tetradentate bis(β-diketonate) europium(III) complex

Eu2(BPOPB)3H2O, an europium complex chelated with bis(β-diketone), was synthesized. Its properties have been investigated by absorption spectrum, emission spectrum and luminescence lifetime measurement. The complex displays strong red luminescence upon irradiation at the ligand band around 355 nm, which indicates that the bis-β-diketonate ligand BPOPB is an efficient sensitizer. The Judd–Ofelt parameters obtained from the emission spectrum of Eu2(BPOPB)3H2O have been used to calculate the total spontaneous emission probabilities (A), the radiative lifetime (τrad), the fluorescence branching ratio (β) and the stimulated emission cross-sections (σ). The luminescence lifetimes are determined to be 402 and 169 μs for Eu2(BPOPB)3H2O and Eu(DBM)3(H2O)2, respectively. The relationship between the structures of rare-earth complexes and luminescence lifetimes was analyzed. The radiative properties reveal that Eu2(BPOPB)3H2O is potential to be an efficient luminescent material.