Abstract: Synthesis of four nine-coordinate lanthanide (III) complexes of the type, [Ln(hfaa)3(tptz)], where Ln=La, Nd, Sm and Tb; hfaa=the anion of 1,1,1,5,5,5-hexafluoro-2,4-pentanedione and tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine, by a new modified one pot in situ method is reported. The lanthanide ions are coordinated to three N-atoms of three 2-pyridyl units of tptz besides six O-atoms of three hfaa units. The formation of these volatile complexes is confirmed by molecular ion peak in ESI-MS, IR and NMR. The hypersensitive 4G5/2, 2G7/2 ← 4I9/2 transition displays distinct band shape which is different from the band shape of known eight- and ten-coordinate complexes. The samarium and terbium complexes emit pink and green luminescence due to 4G5/2 → 6Hj (j=5/2, 7/2, 9/2) and 5D4 → 7F j (j=3-6) transitions, respectively. [ABSTRACT FROM AUTHOR]