Synthesis, structure and long-lived NIR luminescence of lanthanide ate complexes with perfluorinated 2-mercaptobenzothiazole

Abstract

To obtain new efficient lanthanide-based NIR luminophores perfluorinated 2-mercaptobenzothiazole was used as a ligand. The ate-complexes [(Ln(mbt^F)₄)⁻(Na(DME)₃)⁺] of Nd (1), Sm (2), Tb (3), Er (4), Yb (5) and [(Y(mbt^F)₄)⁻(Li(DME)₃)⁺] (6) were synthesized in high yields by the reactions of the respective silylamide compounds Ln[N(SiMe₃)₂]₃ and M[N(SiMe₃)₂] (M = Li, Na) with 4,5,6,7-tetrafluoro-1,3-benzothiazol-2(3H)-thione (Hmbt^F) in DME media. The complexes 1–3 and 6 were structurally characterized by X-ray diffraction analysis. It has been shown that the mbt^F ligands sensitize the luminescence of Nd, Sm, Tb, Er and Yb ions upon mild UV or blue light excitation. The NIR luminescence of crystalline compounds 1, 2, 4 and 6 has been studied by time-resolved techniques. As expected, the compounds exhibit prolonged NIR luminescence due to the removal of C–H groups from lanthanide centers and the absence of C–O bonds in the coordination sphere of the lanthanides. The synthesized compounds are promising materials for NIR laser applications.