Synthesis and investigation of enhanced luminescence of Ln(III)-complexes containing fluorinated β-diketone and oxygen donor ancillary ligands for efficient advanced displays

Abstract

2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (fod) fluorinated β-diketone had been used to prepare a series of Ln3+ (Eu or Tb) ternary complexes with monodentate ancillary ligands such as aqua, urea, triphenylphosphineoxide (TPPO) and pyridine-N-oxide (PNO). Prepared ternary materials Eu(fod)3.(aqua)2 (1), Tb(fod)3.(aqua)2 (2), Eu(fod)3.(urea)2 (3), Tb(fod)3.(urea)2 (4), Eu(fod)3.(TPPO)2 (5), Tb(fod)3.(TPPO)2 (6), Eu(fod)3.(PNO)2 (7), Tb(fod)3.(PNO)2 (8) were illustrated through various structural and photo-physical spectroscopic practices. Emission measurement showed characteristics strong emission in red aa well as green spectral region accredited to the electric dipole 5D0→7F2 and 5D4→7F5 hypersensitive transitions of Eu3+ and Tb3+ ions respectively. An inclusive comparative investigation of enhancement features in the luminescence intensity had been carried out to determine the role of ancillary ligands. Improved luminosity was achieved as auxiliary ligands not only substituted the solvent molecules in coordination sphere but also indirectly sensitize metal ion through transfer of energy to emissive level of respective Ln3+ ion from triplet state of ligand. Decay curve specified uniformity in chemical environment around central metal ion. Efficient red and green light materials could be successfully used for fabricating OLEDs.