Photoluminescent properties of novel tris, ternary and tetrakis Eu(III) organic complexes with 2-acetyl-1,3-indandione ligands

Three structurally different, highly luminescent Eu³⁺ complexes – tris complex Eu(2AID)₃(H₂O), ternary complex Eu(2AID)₃(PHEN) and tetrakis complex [Eu(2AID)₄]N(Et)₄, where 2AID stands for 2-acetyl-1,3-indandione and PHEN for 1,10-phenanthroline, were obtained and characterized with element analysis,1H-NMR, FT-IR and mass spectroscopy. Thermal properties were investigated with thermogravimetric analysis and it was shown, that independently from their structure all three complexes exhibit high thermal stability over 280 ℃. Photophysical properties were investigated in THF solutions, solid-state and poly-N-vinylcarbazole (PVK) films with complex mass of 8%. Complexes exhibit identical UV/Vis absorption and excitation spectra from 250-400 nm in THF, but in solid-state excitation window is shifted to near UV and even visible light region (300-500 nm). In solutions all three complexes exhibit weak emission at 613 nm with low absolute quantum yields (2-3%), but in solid state emission is enhanced and highest quantum yield – 34% was obtained for tetrakis complex. PVK films showed low PLQY. Keywords: Eu³⁺ organic complex, b-diketone ligands, 2-acetyl-1,3-indandione, red light emission, luminescent pvk films