English abstract
Three sets of lanthanide-based coordination polymers (CPs), [Ln(DHTP) (NO3)(H20)4]. [Ln1 = Gdi, Eul, Tb1], [Ln2(DHTPXTTA)4(DMF) (MeOH)2] [Ln2 = Eu2, Tb2, Sm2] and [Ln2(DHTPX(HFAC)4( MOH)2] [Ln3 = Eu3, Tb3] have been synthesized using (2,5 dihydroxyterephthalicacid (DHTP), thenoyltrifluoroacetone (TTA) and hexafluoroacetylacetone (HFAC) ligands by condensation reactions. The single-crystal X-ray diffraction studies revealed that, set one, Lni, has one dimensional (1D) zigzag architectures whereas set two, Ln2, exhibits two-dimensional (2D) architectures. However, for set three, Ln3, whose spectroscopic characterization reveals similar formulae to the Ln2 set, is assumed to have similar structures to set two. A detailed photoluminescence study was carried on Eu(III), Sm(III) and Tb(III) CPs in the solid state. It has been found that the band structure of the DHTP ligand is suitable for luminescence sensitization of Eu(III) and Sm(III) but not for Tb(III). Ln1 CPs have been found to possess shorter lifetimes and smaller quantum yields relative to the rest due to the existence of coordinating water molecules in the coordination sphere. The incorporation of TTA or HFAC units in the coordination sphere of Ln2 and Ln3 CPs has greatly enhanced the luminescence intensity and given relatively longer lifetimes with large quantum yields.
