Crystal Structure and Highly Luminescent Properties Studies of Bis-β-diketonate Lanthanide Complexes

A new
bis­(β-diketonate), 1,3-bis­(4,4,4-trifluoro-1,3-dioxobutyl)­phenyl
(BTP), which contains a trifluorinated alkyl group, has been prepared
for the synthesis of two series of dinuclear lanthanide complexes
with the general formula Ln2(BTP)3L2 [Ln3+ = Eu3+, L = DME­(1), bpy­(2), and phen­(3); Ln3+ = Sm3+, L = DME­(4), bpy­(5), and phen­(6); DME = ethylene glycol dimethyl ether, bpy = 2,2′-bipyridine,
phen = 1,10-phenanthroline]. The crystal structure of the free ligand
has been determined and shows a twisted arrangement of the two binding
sites around the 1,3-phenylene spacer. X-ray crystallographic analysis
reveals that complexes 1, 2, 4, and 5 are triple-stranded dinuclear structures formed
by three bis-bidentate ligands with two lanthanide ions. The room-temperature
photoluminescence (PL) spectra of complexes 1–6 show that this bis-β-diketonate can effectively sensitize
rare earths (Sm3+ and Eu3+) and produce characteristic
emissions of the corresponding Eu3+ and Sm3+ ions. In addition, two bidentate nitrogen ancillary ligands, 2,2′-bipyridine
(bpy) and 1,10-phenanthroline (phen), have been employed to enhance
the luminescence quantum yields and lifetimes of both series of Eu3+ and Sm3+ complexes.