Synthesis, crystal structure and photoluminescence studies of [Eu(dbm)3(impy)] and its polymer-based hybrid film

Abstract

An eight-coordinate Eu(III) complex with 1,3-dibenzoylmethane (Hdbm) and 2-(1H-imidazol-2-yl)pyridine (impy), [Eu(dbm)₃(impy)], was synthesized and characterized via elemental analysis, FTIR spectroscopy, ESI-MS⁺ studies and thermal analysis (TGA/DTA). A distorted square antiprismatic structure for the complex is revealed via single crystal X-ray diffraction analysis. In the complex, Eu(III) is coordinated to six oxygen atoms of three dbm moieties and the pyridyl and imidazolyl nitrogen atoms of impy. Steady state and time resolved photoluminescence spectra of the solid complex, its chloroform solution and its PMMA hybrid film are presented and discussed. In spite of the distorted square antiprismatic structure, the ⁵D₀ → ⁷F₂ transition is fairly strong and the ⁵D₀ → ⁷F₀ transition is sufficiently strong. The decay time is monoexponential for the solid complex, whereas the chloroform solution and PMMA hybrid film show biexponential decay fitting. The decay time of the ⁵D₀ → ⁷F₂ transition of solid [Eu(dbm)₃(impy)] (417 ± 0.5 μs) is seven times longer than that of its precursor [Eu(dbm)₃(H₂O)] (57 ± 0.09 μs). The intrinsic quantum yield of the ternary complex is larger than the precursor. The solid complex and PMMA hybrid film emit a red color, while the chloroform solution emits a pink color. The simultaneous emission of white and red light results in pink.