Improving the emission quantum yield in dinuclear Eu(iii) and Tb(iii) complexes with 2-fluorobenzoate

Abstract

The reaction of Ln(NO₃)₂·6H₂O salts (Ln = Eu and Tb) with an excess of 2-fluorobenzoic acid (H-2FBz) in an ethanol/water mixture allows the isolation of dinuclear compounds with the formula [Ln₂(μ₂-2FBz)₄(2FBz)₂(H-2FBz)₂(H₂O)₂] (Ln = Eu (1) and Tb (2), 2FBz = 2-fluorobenzoate). A solid-state photoluminescence study of complexes 1 and 2 shows the 4f–4f lanthanide transitions in the visible range with improved emission quantum yields. 1 and 2 are water soluble and photoluminescence studies have also been performed in water and D₂O solutions, showing that the emission due to the 4f–4f electronic transitions is still present. The magnetic behaviors of 1 and 2 are also reported.