Synthesis and NIR photoluminescence studies of novel Yb(III) complexes of asymmetric perfluoryl β-diketone

The four new NIR emitting Yb3+ complexes using, perfluorinated beta-diketone (5,5,6,6,7,7,7-heptafluoro-2,2-dimethyl-3,5-octanedione, Hfod) as main chromophore and N- / O- containing neutral heterocyclic bases namely: trispyridyl triazine (tptz) (1), indazole (2), triphenyl phosphine oxide (tppo) (3) and 4,4'-bipyridyl (4,4'-bpy) (4) as ancillary ligands have been successfully designed. The complexes, [Yb(fod)(3)(L)(n)] (n = 1 for tptz, 4,4'-bpy and indazole and 2 for tppo) have been thoroughly characterized by elemental analysis, TGA-DTA, IR and UV-Vis spectroscopy. The complexes display efficient ligand-sensitized near-infrared luminescence from ytterbium at 925-1075 nm with lifetimes and quantum yields as high as 13 mu s and 0.65%, in the solid state, and 12.35 mu s and 0.62% in CHCl3 solution, respectively. The effect of ancillary ligand triplet states on the emission intensity of Yb3+ is discussed.