Synthesis, structure, and photophysical property of series of Ln(III) coordination polymers with different carboxylato ligands (Ln = Sm, Eu)

Abstract

Four Ln(III) coordination polymers, {[Ln2(1,3-bdc)3(H2O)4]·DMF·H2O}n (Ln = Sm 1, Eu 2) and [Ln2(mal)3(H2O)6]n (Ln = Sm 3, Eu 4) (1,3-H2bdc = isophthalate acid, H2mal = malonate acid), were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra, UV–Vis–NIR absorption spectra, and fluorescence spectra. The structural analyses reveal that polymer 1 is a 3D coordination polymer. Its asymmetry unit contains two crystallographically independent Sm(III) ions, both are eight-coordinated. The 1,3-bdc2− anions show three different coordination modes. The structure of polymer 2 is isomorphous with that of 1. Polymer 3 is also a 3D coordination polymer, its asymmetry unit contains one Sm(III) ion, which is nine-coordinate. The mal2− anions have two different coordination modes. The structure of polymer 4 is isomorphous with that of 3. The luminescent study shows that polymers 1, 2, and 4 exhibit characteristic emission bands in the visible region, corresponding to the transitions of the Ln(III) ions. By comparison and analysis of luminescence, it is found that the incidence of the same ligand on the corresponding spectra of different Ln(III) ions is different, and the influence of different ligands on luminescence of the same Ln(III) ion is also very different.