Work

Boranil Chelates as Antennae for Ytterbium(III) Luminescence Sensitization

Year: 2026

Type: article

Abstract: Five original ligands based on bipyridine and phenanthroline chelating units connected to boranil moieties are synthesized and characterized, including single-crystal X-ray diffraction. For classical boranil moieties, large absorption coefficients are observed, together with intense fluorescence. For sulfur-containing boranils, absorption coefficients and fluorescence quantum yields are smaller, but larger Stokes shifts are observed, together with singlet oxygen generation. These features are in line with the time-dependent density functional theory study, which also reproduces well the behavior of the yttrium(III) complexes; more specifically, the positioning of the ligand triplet states, which is in the range of 15,500–20,000 cm –1, as well as the larger spin–orbit coupling allowing better intersystem crossing for sulfur-containing boranils. In addition to ligand-based fluorescence, all five ytterbium complexes show near-infrared emission with quantum yields (Φ Yb L ) in the range of 0.0027–0.0040, lifetimes in the range of 8.8–11.4 μs, and brightness ( B = ε·Φ Ln L ) in the range of 121–163 M –1 ·cm –1 (with 350 nm excitation).

Source: Inorganic Chemistry

DOI: 10.1021/acs.inorgchem.6c00187