Influences of reaction temperature and pH on structural diversity of visible and near-infrared lanthanide coordination compounds based on bipyridyl carboxylate and oxalate ligands

Four series lanthanide coordination compounds, [Ln(bpdc)(ox)0.5(H2O)]n·nH2O (Ln ​= ​La (1), Ce (2), Gd (3)), [Ln(bpdc)(ox)0.5(H2O)2]n (Ln ​= ​Ce (4), Pr (5), Nd (6)), [Ln2(bpdc)2(ox)(H2O)4]n·4nH2O (Ln ​= ​Nd (7), Sm (8)), [Ln2(bpdc)2(ox)(H2O)4]·H2O (Ln ​= ​Er (9), Yb (10)) (H2bpdc ​= ​2,2′-bipyridine-6,6′-dicarboxylic acid, H2ox ​= ​oxalic acid) were achieved under hydrothermal conditions by the reactions of lanthanide trichlorides with a rigid bipyridyl derivative and oxalic acid. Compounds 1–3 present a 6-connected hxl topological net with binuclear [Ln2(bpdc)2]2+ units. Compounds 4–6 display a 3-connected ths ThSi2 topological 3D framework with butterfly-like structure. Compounds 7–8 possess a ladder-shaped chain, and further linked by hydrogen bonds to form a 2D supramolecular layer. Compounds 9–10 show a binuclear molecular structure, and a 2D supramolecular layer structure is formed through hydrogen bonding interactions. Meanwhile, the reaction temperature and pH play important roles on the ultimate structures. These lanthanide compounds exhibit typical visible and near-infrared luminescence, as well as good thermal stability. Four series of new lanthanide coordination compounds have been synthesized under hydrothermal conditions. Compounds 1–10 exhibit variable structures with 0D to 3D when change reaction temperature- and pH of reaction system. These lanthanide compounds exhibit typical visible and near-infrared luminescence. [Display omitted]