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(<b>1</b>), bpy­(<b>2</b>), and phen­(<b>3</b>); Ln³⁺ = Sm³⁺, L = DME­(<b>4</b>), bpy­(<b>5</b>), and phen­(<b>6</b>); 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 <b>1</b>, <b>2</b>, <b>4</b>, and <b>5</b> are triple-stranded dinuclear structures formed by three bis-bidentate ligands with two lanthanide ions. The room-temperature photoluminescence (PL) spectra of complexes <b>1</b>–<b>6</b> 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