Syntheses, structure, and properties of a series of three-dimensional lanthanide-based hybrid frameworks

A novel family of lanthanide hybrid frameworks, {[Ln2(IDA)3]·(H2O)2}n (Ln = Nd (1), Eu (2), Tb (3), Dy(4); H2IDA = iminodiacetic acid), has been synthesized from the self-assembly of the lanthanide ions (Ln3+) with iminodiacetic acid under hydrothermal conditions and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. Structural analyses revealed 1–4 have intricate frameworks with three-dimensional (3D) Ln–O–Ln inorganic connectivity, in which the IDA2- − ligands adopt the different μ(3- and μ(4- bridging forms. The 3D inorganic skeleton of the hybrid can be described as helices of corner-sharing LnN1O8 polyhedra connected by edge-sharing dinuclear Ln2N4O12 units, specified by the Schlafli symbol of 8·.8·.103 as a 82·.10-a (lig) topology. The structures also show intersected lanthanide oxide ring channels occupied by guest water molecules, based on which the reversible de-/rehydration occurs. Photoluminescence measurements indicate 2 and 3 are red and green emitters, respectively, in the solid state at room temperature. Besides, the magnetic properties of 1 have been studied.

On the basis of iminodiacetic acid, a series of unique lanthanide inorganic–organic hybrid frameworks has been hydrothermally synthesized and characterized. These materials feature unusual 3D Ln–O–Ln inorganic skeletons and intersected lanthanide oxide ring channels.Figure optionsDownload as PowerPoint slideHighlights
► Unusual three-dimensional (3D) Ln–O–Ln inorganic skeletons.
► Intersected lanthanide oxide ring channels.
► Reversible de-/rehydration behavior.