Dual-emissive complexes: Visible and near-infrared luminescence from bis-pyrenyl lanthanide(III) complexes

The syntheses and photophysical attributes of a range of dual-emissive lanthanide complexes are described. The simple ligand architecture is based upon a diethylenetriaminepentaacetic acid (DTPA) core and appended with two aminopyrenyl chromophores to yield the fluorescent free ligand Lpyr. Reaction of the ligand with Ln(tris-trifluoromethanosulfate) gave the mononuclear complexes Ln · Lpyr (Ln = Nd, Er, Yb). Luminescence studies revealed that the complexes were emissive in both the near-IR and UV–Vis, the latter resulting from pyrene localised emission (λem = 390 nm), the former from pyrene-sensitised emission of the lanthanide ion (λex = 337 nm). Time-resolved measurements in the near-IR indicated that the number of coordinated solvent molecules for Nd and Yb was <1, confirming the proposed coordination mode of the octadentate Lpyr. The suitability of pyrene as a sensitiser for near-IR emitting lanthanides was further demonstrated in the rare observation of ErIII emission in a non-deuteriated protic medium.

Graphical abstractThe syntheses and photophysical attributes of a range of dual-emissive, bis-pyrenyl lanthanide complexes based on a DTPA architecture are described. Irradiation of the pyrene chromophore results in sensitised near-IR emission from NdIII, ErIII and YbIII.Figure optionsDownload full-size imageDownload as PowerPoint slide