Molecular dysprosium complexes for white-light and near-infrared emission controlled by the coordination environment

A series of single-molecule dysprosium (Dy3+) complexes consisting of β-diketonate ligands, L1 = 4,4,4-trifluoro-1-phenyl-1,3-butadionate and L2 = 4,4,4-trifluoro-1-(4-chlorophenyl)-1,3-butadionate, as water-containing complexes, and the auxiliary triphenylphosphine oxide (tppo) ligand as water-free complexes were investigated as potential white-light emitters. The coordination environment and choice of the ligands play an important role in the behavior of the yellow/blue emission of the Dy3+ complexes (Y: 4F9/2 → 6H13/2 – yellow, and B: 4F9/2 → 6H15/2 and ligand phosphorescence – blue) based on the sensitization efficiency of the Dy3+ ion by the ligands. By introducing the auxiliary tppo ligand in the complex, the relative intensity of the Dy3+ emission increases due to a more efficient sensitization of the Dy3+ ion. The CIE (Commission International d’Eclairage) coordination at room temperature for water-containing, DyL1H2O (0.340, 0.333), and DyL2H2O (0.270, 0.249), and for water-free complexes, DyL1tppo (0.364,0.391) and DyL2tppo (0.316, 0.331), are close to the coordinates of ‘ideal’ white light (0.333, 0.333). The CCT (Correlated Color Temperature) values at room temperature for DyL1H2O (5129 K), DyL2H2O (18,173 K), and DyL2tppo (6319 K) correspond to ‘cold-white-light’ emitters, while the DyL1tppo (4537 K) matches a ‘warm-white-light’ emitter. Beside emitting in the visible (Vis) region, the Dy3+ complexes also show emission in the near-infrared (NIR) part of spectrum, which has been studied in detail.

Publication year:2022

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