Luminescence, magnetism and structures of 1D 3-pyridin-yl-benzoic lanthanide coordination complexes

Reactions of 3-pyridin-3-yl-benzoic acid (HL1) and 3-pyridin-4-yl-benzoic acid (HL2) with lanthanide nitrate hexahydrate under hydrothermal conditions yield four new coordination polymers, namely [Sm2(L1)6(H2O)4]n (1) and [Ln(L2)3(H2O)2·H2O]n (Ln = Nd (2), Gd (3) and Er (4)). X-ray diffraction analysis reveals that 1 is of one-dimensional (1D) zigzag chain arrays featuring two different lanthanide ion centers. In contrast, complexes 2–4 exhibit 1D linear chain arrays exhibiting only one crystallographically distinct lanthanide ion. In addition, two known complexes [Ln(L2)3(H2O)2·H2O]n (Ln = Eu (5), Tb (6)), are also synthesized as well as their triplet energy-levels are investigated, the results reveal that both complexes 5 and 6 are able to emit intensively characteristic red and green luminescence of the Eu3+ and Tb3+ ions with luminescence lifetime of 386.3 μs and 715.8 μs, respectively. Further, magnetic analysis suggests that complex 3 is of an antiferromagnetic character.