High-dimensional frameworks dependent on coordination mode of ligand controlled by acidity of reaction solution. Syntheses, structures, magnetic and fluorescence properties of eight new compounds

Abstract

Eight new compounds [Ln₄(HL)₂(L)₂(H₂O)₁₄(H₂W₁₂O₄₀)]·nH₂O (Ln = La (1), Pr (3), n = 14; Ce (2), n = 12; Nd (4), n = 17. HL⁻ = acidic pyridine-2,6-dicarboxylate, L²⁻ = pyridine-2,6-dicarboxylate) and [Ln₃(HL)₃(H₂O)₁₀(H₂W₁₂O₄₀)]·10H₂O (Ln = La (5), Ce (6), Pr (7), Nd (8)) were conventionally synthesized. Compounds 1–4 are isomorphic and show a 2D structure with (3²6²7²)(3¹4²5¹6²)₂ topology, and compounds 5–8 are also isomorphic and have a 3D framework constructed from [H₂W₁₂O₄₀]⁶⁻ clusters and lanthanide–organic–frameworks. Compounds 1 and 5, 2 and 6, 3 and 7, and 4 and 8 were obtained in the same solution systems, respectively. The formation of these compounds with two types of multidimensional structures mainly depends on the solution acidity and the coordination modes of the ligands. Furthermore, thermal properties of 1–8, fluorescence properties of 4 and 8, and magnetic properties of 2–4 have been examined.