NIR-luminescence from ternary lanthanide [HoIII, PrIII and TmIII] complexes with 1-(2-naphthyl)-4,4,4-trifluoro-1,3-butanedionate

► We study on Ln(tfnd)3dione and Ln(tfnd)3dafone complexes (Ln=Ho, Pr, Tm) based on different synergistic ligands. ► Characteristic NIR luminescence of complexes has been obtained upon excitation of the ligand absorption bands. ► Differences in the luminescence intensity of complexes were further discussed. ► Dione ligand with lower triplet-state energy level than that of Htfnd discourage the luminescence of Ln(tfnd)3dione.