A study on the NIR-luminescence emitted from ternary lanthanide [Er(III), Nd(III) and Yb(III)] complexes containing fluorinated-ligand and 4,5-diazafluoren-9-one

A series of lanthanide complexes Ln(tfnb)(3)dafone, Ln(hfth)(3)dafone and Ln(pfnd)(3)dafone (Ln = Er, Nd and Yb) with fluorinated-ligand 1-(2-naphthyl)-4,4,4-trifluoro-1,3-butanedionate (Htfnb), 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dione (Hhfth) and 4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-pentadecafluoro-1-(naphthalen-2-yl)decane-1,3-dione (Hpfnd) served as main sensitizers, respectively, and 4,5-diazafluoren-9-one (dafone) as the synergistic ligand were synthesized. Upon excitation at the maximum absorption of the ligands, the complexes all show the characteristic near-infrared (NIR) luminescence of the corresponding Ln(3+) ions, which is due to efficient energy transfer from the ligands to the central Ln(3+) ions via an antenna effect. Moreover, an indirect excitation model is proposed and the influence of ligands on the luminescence properties of the complexes is further discussed. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.