Synthesis, structure and luminescence property of 2D lanthanide complexes with 3-fluorophthalate and oxalate

Complexes [Ln2(fpht)2(ox)(H2O)4]·H2O (Ln=Sm 1, Eu 2, Tb 3 and Dy 4; fpht=3-fluorophthalate and ox=oxalate) have been synthesized and structurally characterized by single crystal X-ray diffraction. The four complexes possess similar 2D framework structures constructed from Ln-fpht double-stranded helices and ox linkages. Complexes 2 and 3 display the characteristic emission 5D0→7FJ (J=0–4) transitions of Eu(III) ion and 5D4→7FJ (J=6−3) transitions of Tb(III) ion, respectively. The emission decay curves reveal a monoexponential behavior yielding the lifetime values of 0.266±0.002 ms for 2 and 0.733±0.002 ms for 3. The emission spectrum of 1 shows three weak bands corresponding to the characteristic emission 4G5/2→6H5/2, 4G5/2→6H7/2 and 4G5/2→6H9/2 transitions of Sm(III) ion. The emission spectrum of 4 displays a broad band centered at 438 nm, which comes from the π⁎–π transition of the ligand.