Structure and photoluminescence properties of coordination compound [Eu2(o-MBA)6(phen)2] with high quantum yield

An europium(III) coordination binuclear compound [Eu 2 ( o -MBA) 6 (phen) 2 ] ( o -MBA = ortho -methylbenzoate, phen = 1,10-phenantroline) has been synthesized and investigated by X-ray diffraction method, thermogravimetric analysis (TGA), infrared (IR) and photoluminescence (PL) spectroscopy. The single crystal X-Ray diffraction measurements show that the compound crystallizes in the triclinic centrosymmetric space group P -1. The PL excitation spectrum displays a broad band between 300 and 420 nm and a number of sharp transitions between 384 and 590 nm, which can be attributed to the Eu 3+ 4 f 6 intra-shell excitation transitions. The complex exhibits characteristic narrow, metal-centred emission bands, which are determined by the radiative transitions of the Eu 3+ ion, from the first excited non-degenerate 5 D 0 level to the 7 F J (J = 0–4) manifold. The compound shows intense hypersensitive transition 5 D 0 → 7 F 2 which dominates the PL emission spectrum. The dipole strengths of the transitions were determined from the emission spectra in terms of Judd-Ofelt (JO) intensity parameters Ω λ ( λ = 2, 4). The high intensity bright-red emission of the complex can be attributed to highly polarizable ligands environment and the low site symmetry ( Ci ) around the lanthanide ions. We suppose that the J -mixing effect in the Eu(III) ions is responsible for enhanced peak maximum of the 5 D 0 → 7 F 0 transition. • A binuclear complex [Eu 2 (o-MBA) 6 (phen) 2 ] has been prepared and characterized by XRD, TGA, IR and PL spectroscopy. • A grown crystals comprise two centrosymmetric similar types binuclear molecules with Ci molecular symmetry. • The Eu 2 ( o -MBA) 6 (phen) 2 compound shows a pure bright-red luminescence with the intrinsic quantum yield about 75 %. • The radiative parameters of the complex indicate on a significant potential for applications in photonics.