Structural diversity and near-infrared luminescence of lanthanide coordination polymers with different flexibility and coordination orientation based on bipyridyl carboxylate and dicarboxylate ligands

Three series of new lanthanide coordination polymers, [Ln(bpdc)(suc)0.5(H2O)]n.nH2O (Ln ​= ​La (1), Ce (2), Pr (3), Nd (4)), [Ln2(bpdc)2(1,3-bdc)(H2O)]n·2nH2O (Ln ​= ​Ce (5), Pr (6), Nd (7)), [Ln4(bpdc)4(1,4-bdc)2(H2O)3]n.3nH2O (Ln ​= ​Ce (8), Pr (9), Nd (10)) (H2bpdc ​= ​2,2′-bipyridine-6,6′-dicarboxylic acid, H2suc ​= ​succinic acid, H2(1,3-bdc) ​= ​benzene-1,3-dicarboxylic acid and H2(1,4-bdc) ​= ​benzene-1,4-dicarboxylic acid) have been synthesized by hydrothermal reaction with aliphatic and aromatic auxiliary ligands. Compounds 1–4 possess 2D layers with the hxl topological net. Compounds 5–7 present 2D layers with the sql topological net. Compounds 8–10 display 3D frameworks with the hex topological net. Meanwhile, the influence of coordination orientation of the auxiliary ligands on the final structures are investigated. Compounds 1–10 have good thermal stabilities and compounds 7, 9 and 10 show typical near-infrared luminescence.